Questions re coolant routing

thesameguy · **Joined:** Sat Oct 01, 2016 8:24 pm **Posts:** 652

I thought you were talking about passenger cars!

You really cannot anecdotally equate what is experienced in an OTR truck to what happens in a passenger vehicle. I appreciate the analogy, but if you're trying to suggest the concepts that apply to the biggest vehicles apply directly to the smallest vehicles, you're going to run into issues quickly. The engineering, application, and solutions involved are wildly different. We can't even begin to know anything until we have information about the radiator and fan on one of these trucks.

Ultimately, you can go down whatever road you want. The concerns I raised are widely documented, and I think they're easy enough to dig into further if you'd like. If not, that's fine too.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

thesameguy wrote:

I thought you were talking about passenger cars!

You really cannot anecdotally equate what is experienced in an OTR truck to what happens in a passenger vehicle. I appreciate the analogy, but if you're trying to suggest the concepts that apply to the biggest vehicles apply directly to the smallest vehicles, you're going to run into issues quickly. The engineering, application, and solutions involved are wildly different. We can't even begin to know anything until we have information about the radiator and fan on one of these trucks.

Ultimately, you can go down whatever road you want. The concerns I raised are widely documented, and I think they're easy enough to dig into further if you'd like. If not, that's fine too.

The example flash7210 and I use are diesel powered vehicles that are either empty or are hauling a load... they may be much larger, but the comparison is much closer than the race car example posted here. The CRD engine is diesel, it is used to haul loads and is often off-road, much like a large highway tractor. Diesel engines all have the same heat generation characteristics and heating/cooling graphic curve. They heat differently than gasoline engines, and race engines are another thing altogether.

You offered the example of the 450hp Corvette vs. the 200hp Buick and I am still waiting for the specific engines these vehicles have. A comparison of these two engines would prove to be enlightening, so please provide the specifications on the engines.

I may be guessing, but I suspect that these engines share the same engine block and that the chamber for the thermostat valve is in that block. If this is the case it is likely the ONLY reason why they have the same thermostat valve. The original designers of this common engine block would have designed 1 thermostat valve for it, (perhaps with different opening temperatures, but the same dimensions and design features), capable of handling the heat generated by putting out over 450hp... this does not mean that it is an incorrect valve to use in a 200hp detuned engine. The cooling system engineers are going to design the cooling system components and features in the engine block of any given engine for the maximum amount of horsepower and torque that engine is designed to reliably handle; to do the opposite and design a these components and features to handle only the heat produced by a milder version of that engine would be foolish as they would then have to redesign the entire block to handle the hotter versions.

This explanation would also apply to engines that have the thermostat chamber in the water pump, as is the case in the Hemi V-8 line of gasoline engines. ALL of the HEMI engines use the same thermostat valve, no matter if it is a standard 395hp Ram 1500 pickup truck engine or the 707hp Hellcat engine. The engineers who first designed this engine over 20 years ago knew people would be playing with it and making 800+ hp circle track racing engines out of it, so they designed the basic architecture of the engine to handle this kind of power from the outset. This means a robust set of cooling system passageways with a huge thermostat valve and a matching huge chamber for the valve to fit in it.

I am unclear of the concerns you are raising here. Is it simply that a larger thermostat and thermostat housing can effect adversely affect the dynamic pressure characteristics of the cooling system? If so, please post your evidence as you say it is well documented.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

flash7210 wrote:

TURBO-DIESEL-FREAK wrote:

The concern as posted by thesameguy is pressure differentials created by the water pump. As I just posted earlier, a water pump is a volume pump and does not create pressure in a confined space.

This website put it into words better than I could:
https://bangshift.com/general-news/tech-stories/water-pump-101-whats-really-going-water-inside-engine/

Quote:

This is the pressure that is being controlled by your radiator cap. Meziere refers to this as the static pressure. They refer to the second type of pressure as dynamic, and this is the pressure created by the pump itself. In truth it is the difference in pressure from the outlet side of the water pump and the inlet side of the water pump, and will be highest as it exits the impeller cavity of your water pump, whether mechanical or electric. The water in your cooling system will see different pressure drops as it travels through different areas of the block and heads, and again as it moves through the radiator. Ultimately, the lowest pressure that your system will see is at the outlet of the radiator where fluid returns to the water pump.

“The largest benefit of pressurizing the coolant is the increase in boiling temperature. We all know that boiling fluid will not cool an engine. For each pound of pressure inside of the system the boiling temperature is raised by roughly 2.5 degrees F. Considering pure water with a boiling temp of 212 inside of a system with a 16 pound cap you will have the opportunity to go to (212+[16*2.5]) 252 before the fluid will boil. Dynamic pressure added by the pump increases the pressure where it matters the most – inside the cylinder heads. Fluid needs to flow well over the backside of the combustion chambers or you are in for some big trouble. If your coolant reaches boiling inside the cylinder head you will see detonation very soon thereafter.” says Meziere.

Have you ever seen an engine that won’t cool, even though it has no thermostat in it at all? Have you seen someone use a restrictor in place of a thermostat? While not EVERY system requires a restrictor or thermostat to keep the engine cool, although with rare exception you should be running a thermostat for your engine’s well being, the thermostat and restrictor both provide enough restriction in the flow of coolant out of the engine to help maintain that dynamic pressure level that is required to keep coolant in contact with the walls of the coolant passages. ie Around the combusting chambers in your engine.

This is an interesting article, but the principles being discussed in this article are in the context of racing and competition engines. Yes; there is static pressure and dynamic pressure, but the only times that dynamic pressure issues would ever come into play would be in very highly modified engines for racing or competition. The fellow is talking about 900 to 3000 horsepower engines for crying out loud. That would be like someone trying to get at least 500hp out of a CRD engine.

When discussing competition engines people have to realize that all parameters of engine operation become more far more critical due to the massive increase in specific horsepower and torque. What issues a normal, daily driver engine or even a mildly breathed upon engine has no problem dealing with may lead to a catastrophic failure in a race engine. Dynamic pressure problems in cooling systems - as far as I know - only affect competition engines.

There are no dynamic pressure issues with the Hot Diesel Solutions Model 001. If there were, you would be hearing about them online from really angry Model 001 customers. What you do find if you ask around are customers that are very happy with their product and those that have chosen to monitor their engine temperatures have discovered that the Model 001 actually has a tighter control of engine temperatures in any given driving situation. This is due to the much wider opening/closing stroke the Hemi thermostat offers over the O.E. thermostat valve.

There is a good reason why dynamic flow is not a concern with the Model 001. Firstly, the Model 001 is not a restricter.... the valve inside of it remains closed when the engine is not up to operating temperature or when the engine temperature falls below the opening temperature of the thermostat valve; a restricter is always open. The Model 001 is a true thermostat with a self-regulating valve that allows just enough coolant flow to cool the engine adequately for the heat generated at any given time. The Model 001 may be larger than the O.E. valve, but that only means that it will open up a smaller amount in comparison to the O.E. thermostat in the exact same situation. The flow is not increased and therefore dynamic pressure is not affected, if it ever was a concern.

The ONLY time the Model 001 size and superior flow characteristics would come into play is extreme driving conditions in high ambient temperatures, like maximum allowable towing in a desert, perhaps with a mildly tuned engine that has more power and can therefore create more heat. This may be a situation where the heat generated by the engine out paces the ability of the O.E. thermostat to flow the coolant necessary to keep the engine cool. The Model 001 would have that much more stoke and coolant flow capacity to handle the extra heat generated by the engine. As an extra hedge against overheat situations, with a Model 001 you can change out the valve inside to another Hemi thermostat valve with a lower operating temperature.

CATCRD · **Posted:** Wed Jun 16, 2021 5:16 pm

TURBO-DIESEL-FREAK wrote:

The ONLY time the Model 001 size and superior flow characteristics would come into play is extreme driving conditions in high ambient temperatures, like maximum allowable towing in a desert, perhaps with a mildly tuned engine that has more power and can therefore create more heat. This may be a situation where the heat generated by the engine out paces the ability of the O.E. thermostat to flow the coolant necessary to keep the engine cool. The Model 001 would have that much more stoke and coolant flow capacity to handle the extra heat generated by the engine. As an extra hedge against overheat situations, with a Model 001 you can change out the valve inside to another Hemi thermostat valve with a lower operating temperature.

This has been my observation with the HDS thermostat. I drove from colorado to southern california and back last week in temps of up to 108F. I run the Stant 190F valve. According to Stant it begins to open at 190, and is fully open by 210. Climbing long grades in 100+ heat, with cruise control on 75 mph, the needle would climb to 210 and just stop. Never overheated and nothing in the overflow chamber.

Gypsy62 · **Posted:** Thu Jun 17, 2021 2:02 am

Great exploration of ICE cooling physics!
Interesting insights, one and all.

Re soob 2.5 HG's: engine-out, 100%. In the time it takes you to squeeze-swap the 4 spark-plugs you can have the motor mounted on a stand.

Back in cooling-land, I'm leaning towards the oil-only Dsite Wicked-Wheel'd turbo. The impact that the h2o cooled Garrett may be having on these temp spikes is a wild-card.
Rather than continuing to throw darts trying to stabilize temps, It's tough to ignore backtracking towards stock.

I'd rather revert to an oil-only turbo rather than have to mod my snorkel setup's routing to chase stock coolant routing. Kinda' sucks given the time/work/money into the turb cooling plumbing, but the goal of all-conditions stable temps is king.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

Regarding the following thread:

https://bangshift.com/general-news/tech ... de-engine/

I have taken the time to call up Meziere Enterprises and spoken to Jerry, one of their technical representatives. Meziere Enterprises is the company the article directly references the issues of concern raised by flash7210 and thesameguy regarding dynamic pressure created by engine cooling system water pumps.

I brought the concerns to the attention of Jerry, and he in turn gave me his company e-mail address so I can follow up with a detailed information letter. Here is what I wrote to him...

"Thank you for receiving my call yesterday afternoon. I appreciate the feedback regarding the following article that was posted on a well-known online Jeep Forum; LOSTJEEPS.com.

https://bangshift.com/general-news/tech ... de-engine/

My inquiries are directed to the subject of the dynamic pressure generated by water pumps in internal combustion engines as indicated in this article. I will note that the article was written on October 23, 2014 by people who run an online high performance and competition enthusiast website, and that the concerns related in this article - especially regarding dynamic cooling system pressures - may only be a problem when discussing extreme performance and competition engines. If I am wrong about this, PLEASE advise me as such; as a manufacturer of an upgrade cooling system part I maintain a high standard for myself and the product I manufacture. This means I must always be open to learning more from experts in engine cooling systems.

It has been suggested by H.D.S. Model 001 opponents that because the Model 001, (which I manufacture), is significantly larger than the throwaway original equipment thermostat assembly it replaces, changes are made to the dynamic pressures in the engine and this will cause coolant flow problems in the engine adversely affecting the cooling system efficiency. They claim that this is due to changes in dynamic cooling system pressures in the engine.

My question is simple... Are there adverse effects to the cooling system dynamic pressure in a Jeep Liberty CRD engine, (V.M. Motori R428 turbo-diesel engine), due to the use of a H.D.S. Model 001 engine thermostat assembly? I would think not, due to the fact that a Model 001 thermostat assembly is still a self-regulating valve that precisely controls the amount of coolant flow through the minute stroking open and stroking closed of the HEMI engine thermostat valve inside. Where an O.E. thermostat assembly may have its valve inside open 1/4 of the way in a given driving situation, a Model 001 will likely only be open 1/8 of the way, if it is using a valve with the same opening temperature. The Model 001's greater flow only would come into play under extreme driving conditions and/or if other cooling system components are starting to lose their capacity to cool. I therefore think that the dynamic pressures inside the CRD engine would change very little, if at all.

Please advise regarding my question. Any feedback you can provide would be valuable to me."

Hopefully, I will receive a reply from Jerry or another Meziere Technical Representative sometime soon.

mrhemi · **Joined:** Tue Dec 08, 2015 10:46 am **Posts:** 182

Let me interject some real world experience with the HDS001 thermostat.

I own two CRD's. I have equipped both with an HDS001 203 deg. thermostat. Never had a bit of a problem. I have personally put over 100,000 miles on one of them with the HDS. They have been driven in the Canadian winter, through the mountains, through the desert all loaded up and maintain the 203 deg temp (real time monitoring). One has been driven across the continent 3 times and will do so again.

Enough already. There is no performance issue. If you do not want to pony up for the cost of one, fine, but there is nothing wrong with the design or application. I would utilize another one if I have another CRD.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

O.K. CRD Owners:

I have indeed received an e-mail response from Jerry. Here is what he wrote to me verbatim...

"Hi Jeff

I have reviewed your product and it appears to be a well thought out with good engineering and made to a high quality standard. The concern about dynamic pressure in my opinion is a non issue. The pump pressure created by stock water pump is not much to begin with (compared to a racing water pump) and the very slight pressure drop the larger thermostat would cause(doubt you could measure it) will be made up by the increase in coolant flow. I have almost zero experience with these engines so I cannot comment on running a higher temperature rating thermostat and its effects on longevity of this engine, However a 170’ thermostat in a car sold in Canada seems ridicules."

So it clearly appears that I was wrong about the other type of pressure generated in a cooling system, and that is the fact that I essentially denied the existence of dynamic pressure developed by the water pump. However, as I suspected later, it also clearly appears that dynamic pressure problems caused by improper cooling system modifications and the associated losses in cooling system efficiency are the realm of extremely high horsepower racing engines that use racing water pumps. In cooling systems that use O.E. or O.E. type water pumps that produce a low amount of dynamic pressure, problems of that nature are simply non-existent.

Just to be absolutely sure I have sussed out everything I can regarding this subject, I replied to Jerry's reply and asked for clarification on a few details. I will post those answers as well if he has the time to respond.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

CATCRD and mrhemi:

Thank you very much for your endorsement of the Model 001; it is much appreciated.

Please understand that after reviewing the BangShift.com article as posted earlier in this thread I decided I should properly address the concerns of dynamic pressure of the water pump and the possible problems that might occur when changes are made to a cooling system. I was indeed wrong when I first stated that dynamic pressure does not exist at all, but I was correct in stating later that it is not a problem in anything outside of an extreme horsepower race engine using a very high flow water pump.

I needed to get more details from Meziere Enterprises so that the concerns of other members following this thread are properly addressed. I knew that dynamic pressure problems were not an issue with the Model 001 because I would have heard it from my customers by now if it was a problem. I have had 100% satisfaction with my product, but stating that fact is not enough with some CRD owners and their concerns need to be addressed on a theoretical level using information I have gleaned from experts in this subject.

I am used to this now due to all of the garbage theories I have had to deal with from some people on this forum, and by now you know who they are. Thankfully, in this particular case the concerns were legitimate and two good things resulted from all of my effort to suss out the details of this problem...

1) I am learning a little bit from the real experts at Meziere about the fluid dynamics of water pumps and the whole issue of dynamic pressure; something I had never considered before.

2) Despite missing this aspect of cooling system design, the experts at Meziere seem to think that it is not an issue to be worried about anyway with the Model 001 in the CRD engine. Missing out on dynamic pressure of the water pump is something that I can blame partially on the engineer I consulted with at Stant when I first developed the Model 001 in 2014, but then again if he also thought it was not an issue he probably felt it was better not to bring the subject up at all.

WWDiesel · **Posted:** Sat Jun 19, 2021 12:04 pm

Jeff,
If you actually wanted to know the coolant pressure at the thermostat housing, you could always install a low pressure gauge using one of the extra threaded ports you provided in the thermostat and measure the pressure at normal operating temperature. I would be real surprised if are able to measure any static pressure at this point in the flow path which is right under the thermostat opening.
I still believe the pinch points in the coolant flow of a closed cooling system are probably the head gasket and / or the fluid inlet flues of the radiator.
In the scheme of things, dynamic pressure is really a non issue in the thermostat housing itself when the thermostat is open. :2cents:

Dynamic pressure
Dynamic pressure is the difference between total and static pressure. Dynamic pressure measures the kinetic energy of a fluid, which comes from the fluid’s velocity and density. So dynamic pressure happens in the movement between the point where the water starts moving and the point where it stops.
Quote:
In our case, the antifreeze's density is constant, we don't know the velocity, and the coolant flow is always in motion if the engine is running.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

WWDiesel wrote:

Jeff,
If you actually wanted to know the coolant pressure at the thermostat housing, you could always install a low pressure gauge using one of the extra threaded ports you provided in the thermostat and measure the pressure at normal operating temperature. I would be real surprised if are able to measure any static pressure at this point in the flow path which is right under the thermostat opening.
I still believe the pinch points in the coolant flow of a closed cooling system are probably the head gasket and / or the fluid inlet flues of the radiator.
In the scheme of things, dynamic pressure is really a non issue in the thermostat housing itself when the thermostat is open. :2cents:

Dynamic pressure
Dynamic pressure is the difference between total and static pressure. Dynamic pressure measures the kinetic energy of a fluid, which comes from the fluid’s velocity and density. So dynamic pressure happens in the movement between the point where the water starts moving and the point where it stops.
Quote:
In our case, the antifreeze's density is constant, we don't know the velocity, and the coolant flow is always in motion if the engine is running.

Definitely something to think about.

You may be right regarding some of the pinch points in a cooling system, but the thermostat by its very nature is a pinch point also. Jerry at Meziere Enterprises has agreed with me on this as have other experts like the technical staff at Stant.

WWDiesel · **Posted:** Sat Jun 19, 2021 5:36 pm

TURBO-DIESEL-FREAK wrote:

Definitely something to think about.
You may be right regarding some of the pinch points in a cooling system, but the thermostat by its very nature is a pinch point also. Jerry at Meziere Enterprises has agreed with me on this as have other experts like the technical staff at Stant.

I agree with them IF the thermostat valve is modulating to hold temperature setpoint. But, IF the thermostat valve is 100% open say in a high load situation while towing loads in high ambient heat conditions, then the thermostat valve is NO longer providing restriction in the system and other locations in the cooling system become the controlling flow restrictions or pinch points.

Also keep in mind, attempts to measure any static pressure in a cooling system would always have to take into account the normal designed operating temperature system pressure as maintained by the coolant tank reservoir pressure cap and would have to be measured as a differential pressure ABOVE normal maximum operating pressure.
All this cooling system theory can get really deep! :banghead:

I would quit worrying about your thermostat, it works perfectly in all situations; overheating issues are due to problems in other areas... :wink:

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

WWDiesel wrote:

TURBO-DIESEL-FREAK wrote:

Definitely something to think about.
You may be right regarding some of the pinch points in a cooling system, but the thermostat by its very nature is a pinch point also. Jerry at Meziere Enterprises has agreed with me on this as have other experts like the technical staff at Stant.

I agree with them IF the thermostat valve is modulating to hold temperature setpoint. But, IF the thermostat valve is 100% open say in a high load situation while towing loads in high ambient heat conditions, then the thermostat valve is NO longer providing restriction in the system and other locations in the cooling system become the controlling flow restrictions or pinch points.

Also keep in mind, attempts to measure any static pressure in a cooling system would always have to take into account the normal designed operating temperature system pressure as maintained by the coolant tank reservoir pressure cap and would have to be measured as a differential pressure ABOVE normal maximum operating pressure.
All this cooling system theory can get really deep! :banghead:

I would quit worrying about your thermostat, it works perfectly in all situations; overheating issues are due to problems in other areas... :wink:

My point exactly, WW. The very fact that the valve in the Model 001 is so large means that you have a much larger stroke capacity between fully closed and fully open. The end result is that the ability of the valve to modulate to hold that temperature setpoint is much greater. It is a rare event when someone would drive even a heavily modified CRD engine in conditions where the valve would be fully stroked open.

Cooling system theory may be deep, but you seem to be handling it well. :mrgreen:

And, no, I am not worried about the Model 001; I am trying to alleviate the worries of other people.

WWDiesel · **Posted:** Sun Jun 20, 2021 2:05 am

TURBO-DIESEL-FREAK wrote:

My point exactly, WW. The very fact that the valve in the Model 001 is so large means that you have a much larger stroke capacity between fully closed and fully open. The end result is that the ability of the valve to modulate to hold that temperature setpoint is much greater. It is a rare event when someone would drive even a heavily modified CRD engine in conditions where the valve would be fully stroked open.
Cooling system theory may be deep, but you seem to be handling it well. :mrgreen:

And, no, I am not worried about the Model 001; I am trying to alleviate the worries of other people.

I know you reside in Canada and probably have never experienced the very high heat and humidity conditions of the hot south in the US but we do have it.

But trust me on this one, if you are pulling a loaded trailer in 95 to 100+ temperatures and humidity above 90% up grades and the engine is working hard, it is almost impossible to keep the engine coolant temperature at thermostat setpoint with the hot air going through the radiator. I don't know the mechanical stroke versus temperature of the stock or the Hemi thermostat, but at some point as coolant temperatures rise far enough above setpoint, that valve is certainly going to go to its maximum stroke aka wide open. In this case that is when the larger Hemi thermostat and housing would be most beneficial to allow greater flow to the radiator over a stock thermostat.

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

WWDiesel wrote:

TURBO-DIESEL-FREAK wrote:

My point exactly, WW. The very fact that the valve in the Model 001 is so large means that you have a much larger stroke capacity between fully closed and fully open. The end result is that the ability of the valve to modulate to hold that temperature setpoint is much greater. It is a rare event when someone would drive even a heavily modified CRD engine in conditions where the valve would be fully stroked open.
Cooling system theory may be deep, but you seem to be handling it well. :mrgreen:

And, no, I am not worried about the Model 001; I am trying to alleviate the worries of other people.

I know you reside in Canada and probably have never experienced the very high heat and humidity conditions of the hot south in the US but we do have it.

But trust me on this one, if you are pulling a loaded trailer in 95 to 100+ temperatures and humidity above 90% up grades and the engine is working hard, it is almost impossible to keep the engine coolant temperature at thermostat setpoint with the hot air going through the radiator. I don't know the mechanical stroke versus temperature of the stock or the Hemi thermostat, but at some point as coolant temperatures rise far enough above setpoint, that valve is certainly going to go to its maximum stroke aka wide open. In this case that is when the larger Hemi thermostat and housing would be most beneficial to allow greater flow to the radiator over a stock thermostat.

The Hemi thermostat the Model 001 was designed for is capable of flowing the coolant necessary to keep a 707 HP, 6.2L supercharged V8 from overheating. The differences in flow and stroke between the stock thermostat valve and the Hemi valve can not be properly measured outside of a laboratory, but simply by looking at each valve's original application it is clear that the differences in flow capacities of the two valves are like night and day.

After installation of a Model 001, customers have reported much smaller coolant temperature variations and steadier engine temperatures overall, even in extreme driving conditions and in very hot climates. If the engine temperatures start to climb even after the installation of a Model 001, it has always turned out to be another cooling system component that is failing or otherwise losing it's capacity to cool. Another thing to consider is that in really extreme driving conditions with a CRD engine making considerably more power than stock you may be creating more heat than the entire system is capable of shedding away. At that point it may be necessary to have a custom radiator built.

One of the most common failures is the cooling system fan clutch; your solution of using the G.M. parts you discovered almost 6 years ago is a great upgrade and should provide some measure of increasing cooling system capacity due to the increased amount of air the G.M. parts are capable of moving. On at least one of my Liberty CRD vehicles, when my O.E. fan clutch fails I will be upgrading to the G.M. parts.

viewtopic.php?f=5&t=82941&hilit=g.m.+fan+clutch+1+blade+plastic+fan

WWDiesel · **Posted:** Sun Jun 20, 2021 4:39 pm

TURBO-DIESEL-FREAK wrote:

The Hemi thermostat the Model 001 was designed for is capable of flowing the coolant necessary to keep a 707 HP, 6.2L supercharged V8 from overheating. The differences in flow and stroke between the stock thermostat valve and the Hemi valve can not be properly measured outside of a laboratory, but simply by looking at each valve's original application it is clear that the differences in flow capacities of the two valves are like night and day.

After installation of a Model 001, customers have reported much smaller coolant temperature variations and steadier engine temperatures overall, even in extreme driving conditions and in very hot climates. If the engine temperatures start to climb even after the installation of a Model 001, it has always turned out to be another cooling system component that is failing or otherwise losing it's capacity to cool. Another thing to consider is that in really extreme driving conditions with a CRD engine making considerably more power than stock you may be creating more heat than the entire system is capable of shedding away. At that point it may be necessary to have a custom radiator built.

One of the most common failures is the cooling system fan clutch; your solution of using the G.M. parts you discovered almost 6 years ago is a great upgrade and should provide some measure of increasing cooling system capacity due to the increased amount of air the G.M. parts are capable of moving. On at least one of my Liberty CRD vehicles, when my O.E. fan clutch fails I will be upgrading to the G.M. parts.
viewtopic.php?f=5&t=82941&hilit=g.m.+fan+clutch+1+blade+plastic+fan

I agree and that is exactly what I have been saying all along. If you are having overheating problems, it may be due to something else besides the thermostat especially if you have the HDS one. (Some just always like to pick on the thermostat for some unknown reason)
The GM fan & fan clutch for the big 6.0 L V8 engine will certainly help improve cooling in high load situations, but if you have issues in other areas, it may not be able to fully overcome them.
A thicker 4 flue radiator would be real nice indeed since there is no room to go bigger or taller in the stack area.

Water Wetter or Purple Ice additives may be worth considerations to help with better heat transfer?
https://www.redlineoil.com/waterwetter
https://www.royalpurple.com/product/pur ... optimizer/
:SOMBRERO:

TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

"I agree and that is exactly what I have been saying all along. If you are having overheating problems, it may be due to something else besides the thermostat especially if you have the HDS one. (Some just always like to pick on the thermostat for some unknown reason)
The GM fan & fan clutch for the big 6.0 L V8 engine will certainly help improve cooling in high load situations, but if you have issues in other areas, it may not be able to fully overcome them.
A thicker 4 flue radiator would be real nice indeed since there is no room to go bigger or taller in the stack area."

-- Great minds think alike, WW!

"Water Wetter or Purple Ice additives may be worth considerations to help with better heat transfer?"

I don't count on such things... if it works, great, but a cooling system should work under all conditions using just the recommended type of coolant in the 50/50 to 67 coolant/33 water range of ratios with distilled water as the preferred choice of H2O.

WWDiesel · **Posted:** Mon Jun 21, 2021 2:10 pm

TURBO-DIESEL-FREAK wrote:

-- Great minds think alike, WW! (darn that's scary!) :dizzy:

"Water Wetter or Purple Ice additives may be worth considerations to help with better heat transfer?"
I don't count on such things... if it works, great, but a cooling system should work under all conditions using just the recommended type of coolant in the 50/50 to 67 coolant/33 water range of ratios with distilled water as the preferred choice of H2O.

I don't know how much one of these products improves heat transfer from the liquid to the metal for heat removal, but if they actually work as advertised, then they certainly are worth the small cost.

I know from working in the power plant industry for many years where we had hundreds of heat exchangers including air to air, gas to water, liquid to liquid, water to water, and oil to water, the the type or metallurgic composition of the metal tubes in a cooler makes a huge difference in heat transfer properties and rates. Aluminum, copper, nickel, azimuth, stainless steel, mixtures of them, etc... all metals have different heat transfer properties, some much better than others.

Another odd thing that is never mentioned in discussing engine cooling is "backpressure" in the cooler/radiator. In the power plant, we were more concerned about cooling water back pressure in a cooler than we were about the supply side pressure. Most all coolers had backpressure regulators along with highpoint vents to make darn sure they were always completely full of the cooling water passing through the cooler. This made sure that all tubes in the cooler were always being utilized 100%.

Think about it, this is a horizonal crossflow type radiator and if the inlet side is NOT completely full of coolant, (aka air bubble in the top) then some of the upper cooling flutes may not be being fully utilized.
Just a left field thought! :dizzy:

I am thinking a permanent vent off the top of radiator vent port that is always in service. Some vehicles like ours with no top radiator cap and a remote reservoir actually have them from the factory to ensure no air bubbles can form or be trapped in the top of the radiator.
You know some radiators are vertical downflow and you don't have to worry about this.
Now if someone would just made a double pass or triple pass radiator for our Jeeps... :idea:

Just some random thoughts... :ALONE:

layback40 · **Posted:** Mon Jun 21, 2021 7:51 pm

WWDiesel wrote:

TURBO-DIESEL-FREAK wrote:

--

Another odd thing that is never mentioned in discussing engine cooling is "backpressure" in the cooler/radiator. In the power plant, we were more concerned about cooling water back pressure in a cooler than we were about the supply side pressure. Most all coolers had backpressure regulators along with highpoint vents to make darn sure they were always completely full of the cooling water passing through the cooler. This made sure that all tubes in the cooler were always being utilized 100%.

Think about it, this is a horizonal crossflow type radiator and if the inlet side is NOT completely full of coolant, (aka air bubble in the top) then some of the upper cooling flutes may not be being fully utilized.
Just a left field thought! :dizzy:

I am thinking a permanent vent off the top of radiator vent port that is always in service. Some vehicles like ours with no top radiator cap and a remote reservoir actually have them from the factory to ensure no air bubbles can form or be trapped in the top of the radiator.
You know some radiators are vertical downflow and you don't have to worry about this.
Now if someone would just made a double pass or triple pass radiator for our Jeeps... :idea:

Just some random thoughts... :ALONE:

I was under the impression that the small outlet on the top of the radiator was to do this. Maybe it only used when filling?
On the XJ diesel (VM425) they have a bleed in the top tank going back to the remote tank. Its only a very small flow, any gas leak can be seen easy.

WWDiesel · **Posted:** Mon Jun 21, 2021 9:50 pm

layback40 wrote:

I was under the impression that the small outlet on the top of the radiator was to do this. Maybe it only used when filling?
On the XJ diesel (VM425) they have a bleed in the top tank going back to the remote tank. Its only a very small flow, any gas leak can be seen easy.

Yep, you are correct, I forgot about that small vent hose. Oh well... :banghead:

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