This is THE assumption.
But as you and others have pointed out, there other unblocked paths for coolant to travel.
No one really knows what is going on with temperatures throughout the engine.
Until someone puts temperature probes all over the cylinder head we will never be certain.

It could be that head gasket failures, cracked heads, and cracked blocks have nothing to do with the thermostat or the various paths by which coolant flows.
All the dedicated CRD owners here are grabbing up every opportunity to ensure that their engine will last 300,000+ miles without catastrophic failure.



This is in fact true.
Even a fully functional factory thermostat will open at 175 and on a hot summer day, with the A/C on, moving through slow city traffic, the coolant temp will get to 195+.
Even when I tested my ZERO thermostat the coolant temp got to 195+.

But we all know that a stuck closed thermostat is bad.
And running with ZERO thermostat, or one that is stuck fully open, is not good either.

What if the thermostat is stuck partially open, with the bypass partially closed?
Or what if the thermostat fails by opening too soon for whatever reason?
We know that these conditions cause the engine to run too cool in winter and engine efficiency is lost.

Here is another what if...

What if the VM engineers never considered emissions controls and actually got it right by using a thermostat that opens at 175?
Maybe they recognized that a cast iron block and a aluminum head heat up and expand at different rates and using a 175 thermostat was their way of controlling thermal expansion of weak cylinder head.

(*Rant* Seriously, have you looked at the cylinder head? All the cast-in recesses, especially around the intake ports and valves? I mean, I get it. Its about keeping oil from pooling on top of the head and letting it flow back down to the pan. But its like they went through great lengths to save every ounce of aluminum possible.)

_________________
U.S. Army Retired

I really have nothing to add to this thread other then some observations using a fairly new OEM, inline and now the HDS.

I bought my CRD with a rebuilt engine and it had a new OEM thermostat. The needle was on the line just left of center but my torque app showed a maximum temp of 167 in cool/cold weather. The highest I saw was 172 while towing a trailer during a trip to FL.

I put in a 192 degree inline and installed it as close to the OEM as possible. It worked great but I would get little spikes of heat on the torque app while warming up. It would get into the low 200's before the inline would open and then it would drop to upper 180's. These cycles would continue as the engine warmed but with less peaking at higher and lower temps. I never towed with this setup or drove in hot weather.

The HDS gets to 202 degrees, drops to 199 then cycles between 200 and 202. I removed the mechanical fan over the summer and drove in some mid-90 degree temperatures without issue. I had one brief heat-up while driving with air conditioning in very slow traffic. I think it may have gotten to 220. Once traffic started moving, it dropped down to 202 - this is without a mechanical fan.

Chris.

These are interesting observations. I have one question. Had the OEM thermostat failed open when you put in the inline thermostat or was it still functioning?

I think the OEM was still functioning, but it was opening at ~167 degrees instead of 176 (?). I still have it if anybody needs one.

That may explain why you were seeing temperature spikes with both thermostats functioning.

Jeff, why do I not see a difference on the temp gauge? Why does it not overheat? Has anyone checked temperatures while running an OEM t-stat? It may open at 175F but when running normally at speed is the engine closer to 195 F.[/quote]


To the best of my understanding, the O.E. temperature gauge is inaccurate, and does not indicate temperature increases at consistent intervals, (I hope I am making myself clear here).

When my O.E. thermostat assembly was new and the engine was fully warmed up, the needle on the factory temperature gauge was just a hair left of vertical. That needle is in the exact same spot when the engine is fully warmed up when the H.D.S. Model 001 is installed. I KNOW the engine was running cooler with the O.E. thermostat - 176 degrees vs 203 with the Model 001, because we measured the difference with an OBD2 reader, so the only conclusion I can come to is the factory gauge is inaccurate.

This is just one of the reasons why the Gen 2 Model 001 has threaded accessory ports... now the customer can easily install an accurate aftermarket engine temperature gauge. They make conversions to electric cooling fans easier as well. You can't do that with the in-line thermostat alternatives.

_________________
U.S. Army Retired

My gauge always sits right between the 176F & 216F marks whether with the OEM t-stat or the inline t-stat. I would think I would see a 20 degree difference. Either way F5hunter had pretty consistent temps with the inline t-stat when he ran it.

joelukex4:

The above comment does not mean much, as it has clearly been shown that the O.E. engine temperature gauge is not accurate, and by that I mean that it does not indicate temperature in a linear manner... take another close look at the following image and you will see what I mean...



There are huge differences in indicated temperature increases for every increment on the gauge. There is a 40 degree jump in temperature - from 176 degrees to 216 degrees - in one increment just to the left of dead-center, and then only a 3 degree jump in temperature - from 216 degrees to 219 degrees - in the next increment just to the right of dead-center. The O.E. gauge is not accurate at all, and can not be used in any thorough analysis of what works and what doesn't in the CRD cooling system.

The only way to get an accurate reading of the engine's temperature is to actually measure it with an OBDII reader or a similar diagnostic tool. What I mean by all of this is that you may still be running too cool, even if the temperature needle is pointing almost straight up. You may indeed be running 20 degrees hotter with the inline thermostat valve and not even realize it without actually measuring engine temperature with a diagnostic tool.

Running with a consistent temperature is important... but you did not say what the needle was doing during warm-up of the engine.

I don't know if my gauge cluster had been updated per TSB08-043005 or not but I do know that upon warm up my gauge proceeds up to a c-hair to the left of center quickly while driving slow and stays there for the entire time the CRD is running. This is independent of whether it is summer or winter. I will say that I run constantly with a FIA front. I have no reason to change unless your pricing becomes more realistic.

Check it with a OBDII reader, and then show the results to a professionally trained diesel technician. Does the needle fluctuate during warm-up?

Nobody is twisting your arm joelukex4... if you want to play engineer and re-design the cooling system with your inline thermostat, that is your perogative.

What get me scratching my head is that it is now common knowledge that the cylinder head gasket integrity and indeed the cylinder head itself are considered "delicate" on these engines. This is the case with all internal combustion engines that have an aluminum head on an iron block, but especially diesels. Why the H-E double hockey sticks would any CRD owner install anything that would put these two items at further risk is absolutely beyond me.

As I have mentioned before regarding my pricing... cross my palm with a contract to build 5000 units, and I can get them made for about $250.00 USD.

I leave for a few weeks and this thread blows up.

I was running a 195F stant inline so my temp increase was marginal when I switched to the HDS. I can say though that my Jeep is running smoother than it ever has. I thought that installing a lift pump was going to be a cure for choppy idle and things like that but the difference was negligible. with the HDS 001 I am seeing way smoother idle and the engine seems to just run happier than it ever has. I put it in when we were just about to change to winter blend diesel here so I ended up losing about 1 mpg anyways so I cannot comment there.

The way I look at it is that I know that the HDS is going to function well without the potential negative side effects of an inline. It did cost a lot, but look at my signiture. Look at all the crap I have put into this Jeep as repair/preventative maintenance. You all can total those parts up, between the GDE Tune, Mishimoto IC hoses, Racor Filter Head+new fuel temp probe, Lift Pump, and Week's Stage 1 there is a lot of money in the jeep. I haven't even gotten around to ARP studs or a torque converter. Not only that, but a lot of those parts took a LOT of time and effort to put in. The HDS was pricey, but it was an easy install. The total Time+$ value was not anywhere near what some of these others were.

_________________
2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

I have a Gen 1 HDS, and I got mine at a super price because another member had it but wanted a Gen 2. I would say to TDF that there is another way to reduce the cost of your unit, and I'm sure that you have considered it, and you have your reasons for not doing it, although it seems to make sense to me. You could cut up stock units like Kap did, and only manufacture the top, or like he did, find a neck that works. You wouldn't even have to do cores and used stats, you could cut up new units. You could even use the cheap Crown castings, because you would be replacing the stat and it's not the casting that is going to fail. The Crown casting at $80 (or even the OE at $140) has got to be way cheaper than what you pay for the housing machined from billet. If you did this, you could offer the stat done on a new unit, or on a used one with a core charge. I would guess that there is another thermostat neck other than the discontinued Kia that could be adapted to work making machining even less. I don't know how many units you have sold, but I would guess that you are getting near saturation for the CRD owners willing to buy the fully machined unit.

_________________
JBA 4" lift, IRO Tri-link w/ wwdiesel bracket, JBA sliders, 235/85-16 Goodyear Wrangler Duratracs, Mercedes Benz forged ultralight wheels, Weeks stage 1 and 2, Weeks lift pump and harness, Weeks battery tray and AGM battery, GDE tune, Suncoast TC, updated front pump, HDS 001 T-stat, ARP studs, Front and rear Detroit/Eaton Truetrac LSD.

I am currently working on this route. I have cut apart my old thermostat and have machined two rings to accept the Hemi thermostat. My plan is to reuse only the neck portion of the elbow and weld it into the top removable ring. It will probably be two or three weeks before I finish, get it installed on my vehicle and do testing. I plan on posting pics if all goes well. It has been a lot of work gathering tooling and basically rebuilding parts of my brothers old atlas lathe to get it working properly so I can do the machining easily. I will keep you posted...

_________________
2006 Liberty CRD 275K, JBA 2.5 with Fox Shocks, GDE Turbo Kit, GDE TCM Tune, Suncoast TC, OEM fuel filter housing converted to fit Caterpillar Fuel Filter 1R-0749, OEM themostat housing modified to accept Hemi 203 F thermostat.

I just chiseled the casting in to two pieces. Thanks to OP for donating the OEM thermostat. I do have a lathe and milling machine so if you have any plans for the rings then please share.

Thanks,
JIgar

_________________
'06 Liberty CRD Limited. Bought at 91K miles.
ARP studs, New rockers, Stant inline tstat, Weeks 1&2, Provent, IDParts Silicone hoses,
2-1/2" Full OME lift, Timing belt, Water pump, TransGo kit, Plastic fan, Fumoto
2nd gen fuel head with 2nd stage 2 micron filter, in-tank lift pump, G2 Rear Diff Cover

Will do.

_________________
2006 Liberty CRD 275K, JBA 2.5 with Fox Shocks, GDE Turbo Kit, GDE TCM Tune, Suncoast TC, OEM fuel filter housing converted to fit Caterpillar Fuel Filter 1R-0749, OEM themostat housing modified to accept Hemi 203 F thermostat.

Wow... where to start?

I WANT TO STATE FOR THE RECORD THAT I BELIEVE MARK KAPALCZYNSKI CREATED A VERY GOOD MODIFIED O.E. THERMOSTAT, AND THAT HIS CREATION IS AS GOOD AS ANYONE CAN REASONABLY EXPECT GIVEN WHAT HE HAD TO WORK WITH.

I did initially try to copy Mark Kapalczynski's modified O.E. thermostat assembly, but I abandoned the idea for the following 5 reasons...

1) Indeed, the cap that Kap sourced is no longer available, and I would have to source another, or make one myself.

2) I do not have access, nor do I own machining equipment of any kind. I was going to get my partner to do the work as he does have some machining equipment, but he is a VERY busy family guy. Just getting him to craft simple plugs for media blasting the Model 001 is like pulling teeth. Trying to get him to somehow copy Kap's design would be impossible to do with any kind of meaningful results, (numbers of units made). This leaves the bulk of the work to a professional machine shop, where the cost of labor is about $100.00 per hour. If I am going to pay a business 100/hour for work, I am certainly not going to use substandard materials like aluminum castings to machine with, especially when top quality materials like 6061 aluminum make up less than 20% of the cost of machining the housings, the caps and the hose barbs.

3) If I were to go with a modified O.E. design, the machine shop would not guarantee the work, because they are cutting open and machining cheap castings, which were never designed to be used for that purpose. There is no possible way to make the modified O.E. thermostat housing even as strong as a stock O.E. thermostat assembly, let alone the Model 001s CNC machined housing and cap. I have some major concerns with that as it is going to be used in a heated and pressurized closed loop cooling system. The modified O.E. thermostat would therefore be sold with no guarantees whatsoever.

If you actually look at Kap's design, there are only 2 skinny 6mm studs holding the thing together, because there is only enough pot metal in 2 areas of the casting to take at the most a 6mm threaded hole. Kap's design also has no less than 2 gaskets in the housing, along with the O.E. thermostat-to-engine gasket, for a total of 3 gaskets... each of these gaskets are a weak link in the design. As an example of how cheap the O.E. thermostat assembly is was when I had to send an unfinished assembled Model 001 to a customer in an emergency because his CRDs thermostat not only failed, but the HOUSING CRACKED AT THE CRIMPED SEAM AND WAS LEAKING COOLANT.

The H.D.S. Model 001, on the other hand, is very strong and will never be an issue for my customers. The housings, caps and hose barbs are machined from 6061 aluminum and the wall thickness throughout the housing and cap are a minimum 0.150" thick; this will withstand pressures many times what the cooling system can generate. The cap is held on by 3 - 8mm studs rather than Kap's 2 - 6mm stud set-up. All of this was possible because I had the foresight to realize that starting with a clean-sheet design was way better than struggling with the limitations posed by the existing O.E. design.

4) The whole core exchange program initiated by Mark Kapaczynski was a logistical nightmare and a pain in the rear. Just ask those individuals who were waiting for Kap to send them a modified O.E. thermostat assembly. People are already waiting long enough to have the Model 001 done... between waiting for O.E. thermostat cores to arrive, and my partner to do the work, CRD owners would be waiting for over a year to have their units modified like Kap's.

5) I discovered by doing proper research and discussing the issue with an actual engineer at Stant Corporation in Connersville, Indiana, that Mark Kapalczynski's modified O.E. thermostat does have some limitations...

A) ... due to the size of the O.E. housing, Kap had a very limited choice of thermostat valves to use. He only found one that fit, and it is only available in one temperature, which is about 195 degrees Fahrenheit. This is an O.K. temperature; however, over 200 degrees is better for a diesel. It is also not a common thermostat valve, and it is unclear to me how much longer it will be manufactured, it's application apparently for a Hyundai Accent from 1995 - 1999.

The Model 001 again benefits from being a clean-sheet design because I can design a housing around any double-acting, (single wax pellet operating both the main valve and a bypass valve), thermostat valve I choose. With the recommendation of this engineer at Stant - the same company that manufactures that inline thermostat valve that some of you insist is O.K. to use - I chose the thermostat valves that fit the entire line of Hemi V-8 gasoline engines from Chrysler. Why? Because they are a double acting thermostat for a hugely successful line of domestic V-8 engines, so they will ALWAYS be available in any jobber parts store for many years to come. They are available in 3 different temperature openings, all of which are hotter than the O.E. thermostat assembly's opening temperature. Due to the huge numbers of valves sold, they will also always be at a reasonable price. They even have the benefit of coming with an "O" ring seal around the flange... my customers will never have to purchase or make a gasket either. These convenience factors cannot be simply dismissed when the alternative can possibly be spending major time and money on an aftermarket design around some obscure thermostat valve that is no longer made one year after production starts.

I would like to point out that by making this specific recommendation of using the Hemi thermostat valves and explaining his reasons to me as to why he made those recommendations, the Stant engineer I spoke to at length when I was developing the Model 001 did not recommend the in-line valve. We discussed the in-line valve option briefly, and he said to stay away from it for the same reasons I have stated several times on this forum... the main reason being that it does not operate the bypass valve and therefore the bypass circuit is rendered inoperable when the O.E. thermostat fails open.

B) ... The engineer at Stant went out of his way to point out that - as a measure of mechanical safety and reliability under severe driving conditions - a thermostat valve that is hotter than manufacturer’s specifications should be a LARGER thermostat valve in any given situation where all other factors remain the same. This will increase flow to the radiator when the valve finally does open up to assure good coolant flow as a counter-measure to the hotter coolant temperatures. The thermostat valve chosen by Mark Kapalczynski is essentially no larger than the O.E. one it replaces, simply because it has to fit into the same size housing.

The Model 001 - again thanks to a clean-sheet design - is significantly larger than either the O.E. valve or Kap's valve. I have taken great care to enlarge the passages and ports in the housings and hose barbs to assure excellent coolant flow. If your CRD overheats, it will not be because of the Model 001, despite being delivered with a much hotter thermostat valve.

Dent, you write that I would not have to deal with a core exchange program if I purchased new O.E. thermostat valves and modified those instead. You need to re-think your cost/benefit analysis on this.

While it is indeed true that I would not have to deal with cores and/or my customers would not have to wait to drive their CRDs if I were to buy new O.E. thermostat assemblies, the cost savings over CNC machined housings and caps would be minimal. Even if I could get O.E. replica Crown thermostats at $80.00 USD, that is at least $114.00 CDN, plus shipping, plus taxes. A conservative estimate for each Crown thermostat would be about $150.00 CDN, (O.E. genuine Mopar parts are $220.00 from the stealerships). Add at least $50.00 - probably more - labor to each thermostat housing to be modified, and you are at least $200.00 CDN cost for each, not including the cap.

If I were to find a similar cap that Kap used I would be lucky... more likely I would have to design a new one. That would be at least $3000.00 development costs - if I am lucky - and about $75.00 each to manufacture, (I know this because that is what the Model 001 cap costs to make).

The CNC machined housings and hose barbs cost me $275.00 CDN, including the cap.... what is the point of modifying inferior O.E. castings when the CNC version which is superior in so many ways can be had for essentially the same amount of money spent?

Regarding the statements written earlier in this thread where joelukex4 writes...

"Are we to assume that no flow is taking place throughout the engine when the bypass is blocked."

To this I say definitely "Y-E-S", but only during warm-up of the engine when the main valve to the radiator is closed. Why would engineers at V.M. Motori bother to design a coolant bypass circuit for absolutely no reason? Coolant bypass circuits have been deemed necessary on internal combustion engines since before your grandfather had his driver's license because it was determined that a major cause of cylinder head gasket failures were caused by uneven warm-up of the engine.

The reply by flash7210 is essentially a false argument...

"This is THE assumption.
But as you and others have pointed out, there other unblocked paths for coolant to travel."

Those unblocked coolant passages - such as those that go to the EGR and to the heater core to warm the cabin of the Liberty - do not properly circulate though the engine... that is why the bypass circuit exists.

flash7210 further writes...

"No one really knows what is going on with temperatures throughout the engine.
Until someone puts temperature probes all over the cylinder head we will never be certain."

To this I reply that it appears to me that flash7210 wants to question the last 80 odd years of research and development of engine manufacturers the world over, all of whom agree that a coolant system bypass circuit is necessary for the long-term reliability of the engines they manufacture. The huge body of evidence from everyone who manufactures engines states emphatically that a bypass circuit is absolutely necessary; who is flash7210 to say otherwise? What is next, flash7210... are you going to question the benefits of pressurized lubrication?

Actually, I wasnt questioning the need for a bypass circuit but questioning the overall design of the factory thermostat.
Yes, the thermostat and bypass circuit are designed to promote even temperatures throughout the engine. But how do you know, even with a fully funtional thermostat, that cylinder 4 isnt running hotter than cylinder 1? Thats why I suggested temperature probes on the head.

And engineers arent perfect. Sometimes things do go as planned and a work around must be found.
Thats why I suggested:

_________________
U.S. Army Retired

I always envisaged drilling holes through the top housing to join the two halves together, never really liked this idea, but just reusing the neck is certainly a possibility. Thinking more about this if the rings are made a bit larger than the housing one can be welded to the top housing, the other to the bottom housing and the thermostat sandwiched between them. The resultant flanges can be used to bolt the two halves together. Machining of the existing housing would be minimal and restricted to cleaning up the surfaces after removing the crimp, material costs for the rings (flanges) would be minimal. The only unknown is how well the casting will weld.


These are fair comments that only Chrysler/VM can answer. It's certainly not unreasonable to assume that a thermostat with a lower temperature than would normally be regarded as optimal was selected as a work around because their actual measurements did not align with their thermal modeling and simulations.

_________________
Share your ideas freely at https://www.facebook.com/groups/libertydiesels/

Flash 7210:

Everyone knows that no mechanical system of any kind exists in this world that is absolutely perfect. To use this as an excuse to modify any system - in this case a cooling system - without knowing for certain the outcomes is absolute folly, ESPECIALLY when dealing with...

1) ... a turbo-diesel engine, (high compression).

2) ... with an aluminum head on an iron block, (two different rates of expansion/contraction during heat/cool cycles).

I agree: Engineers are human beings and therefore not perfect as well as the fact that the cooling system in the CRD is flawed/outdated. Often is the case where things do not go as planned and alternative solutions must be found, but those solutions must be done properly... that is why I developed the H.D.S. Model 001. However, to say now that "anything goes" for modifications like the in-line thermostat valve is to take that somewhat flawed cooling system and now introduce more flaws into it.

The Hot Diesel Solutions Model 001 engine thermostat assembly is the only reasonable choice here because it does NOT modify the cooling system. In fact, it exactly imitates what the O.E. thermostat assembly does but performs far better by giving the CRD owner who has one the following...

1) ... a choice of thermostat valve temperatures to choose from, all of which are hotter than the terrible 176 degree opening temperature of the O.E. valve.

2) ... easy serviceability; all you have to do now is drain the coolant, unbolt the cap, take out the old valve, pop in a new one, bolt the cap back on, and re-fill with coolant.

3) ... superior construction quality and materials... it will never break.

4) ... far superior flow to the O.E. thermostat assembly. You can run your engine to the limit with a Model 001 and not worry about coolant restrictions causing an overheat condition.

5) ... properly placed accessory ports for aftermarket temperature sending units.

Finally, to suggest that 176 degrees is a correct temperature for the R428 is to go against the recommendations of EVERY diesel engine technician I have EVER discussed this issue with. They ALL say this is too cool a temperature for optimum reliability and performance. This is also borne out by the feedback of hundreds of CRD owners, all of whom have experienced reliability issues and poor performance directly related to running the engine too cool. Recall all of those choked-out intake tracts... aside from the fact that the pollution control systems are terrible and should not be there in the first place, they are made worse because the engine never comes up to an appropriately high operating temperature to burn at least some of the pollutants off.

Your suggestion that the 176 degree opening temperature of the O.E. thermostat may have been done deliberately because the engineers wanted to combat the cylinder head warpage/gasket issues shows a lack of understanding of the operation of the bypass system and when it is important that it comes into play.

The damage caused by a lack of a bypass system or a disabled system does not happen at the full operating temperature of the engine; it happens during warm-up, well below 176 degrees... having a 176 degree thermostat valve or a 203 degree thermostat valve makes no difference at all in this regard.

I just checked out the thermostat valve opening temperatures of VW turbo-diesel engines... they have recommended thermostat valve openings as high as 215 degrees Fahrenheit. All of their diesel engines have been aluminum head on iron block, and none of the head gasket issues those engines have had have ever been traced to the thermostat valve or assembly.