Is there a good thermostat solution?

Science and Energy · **Joined:** Thu Mar 30, 2017 9:12 am **Posts:** 246

Hello,
I see there is a flood of history regarding the troublesome thermostat/housing. I saw some early references to using an inline thermostat, a couple of different housing redesigns, etc. Has any strong opinions or I dare say a consensus formed in the community about a good non-500 dollar solution. I would like the diesel to be a little warmer and not have that stupid one piece design. My last motor was an OM617 Mercedes so I have only that experience with diesel motors.

flash7210 · **Posted:** Fri Mar 31, 2017 9:27 am

The HDS is definitely the best thermostat that money can buy.
But you cant go wrong installing a OE factory replacement (not crown).
Any other modified thermostat setup is completely up to you to decide.

Just dont do a dual thermostat (i.e. factory thermostat + inline thermostat).

I did my own kind of thermostat modification, but I wont claim it to be as good or better than any of the others.
Lots of info out there to help you make a decision.

WWDiesel · **Posted:** Fri Mar 31, 2017 10:16 am

X2 with everything flash advised!
Just do not install the in-line in the hose thermostat; there is a strong consensus by several members on this forum that the in-line thermostat can cause head overheating when running both an in-line and the OEM thermostat that has failed in the open position thus keeping the bypass valve closed all the time. Head overheating can cause a cracked head or a blown head gasket! :grim:

In this condition, with the bypass closed and until the in-line stat opens, there is NO or very little coolant flow through the head during the critical warm up period! :roll:

Best and cheapest option is to just replace thermostat with a OEM unit. (NON-CROWN)
Mopar OEM units can be purchased for a little over 100+ dollars at many of the on-line Mopar dealers like:
http://www.factorychryslerparts.com/pro ... 601AA.html

Now if you got some extra money, that HDS is super nice... :wink:

Science and Energy · **Joined:** Thu Mar 30, 2017 9:12 am **Posts:** 246

If I did a stock replacement it would still be at the low temp setting right or did mopar up the temp later?
Could someone destroy the thermostat inside the housing and simply install an inline immediately after? Sorta like gut it out. The advantage would be ease of service after and a higher temp setting.

WWDiesel · **Posted:** Fri Mar 31, 2017 12:34 pm

Science and Energy wrote:

If I did a stock replacement it would still be at the low temp setting right or did mopar up the temp later?
Could someone destroy the thermostat inside the housing and simply install an inline immediately after? Sorta like gut it out. The advantage would be ease of service after and a higher temp setting.

An OEM thermostat would still be at the stock temperature. I believe the lower temperature was some kind of stupid emission thing to keep NOX down?

Only problem with using a gutted housing and in-line thermostat; the bypass circuit would be 100% open all the time and that is a straight shot from the housing to the water pump's suction inlet so you would be bypassing 100% all the time. That could cause overheating problems big time!!!

The bypass valve has to be in the circuit and functional at all times for correct engine warming and temperature control.
A fully operational OEM or HDS stat controls the bypass valve and closes it off proportionally while at the same time the main thermostat valve is opening up to send flow through the radiator. As the main thermostat valve opens, the bypass valve closes off and the main valve is open and modulating to control temperature at setpoint. The main valve and the bypass valves opening rates and positions are not fully linear with each other, but rather proportional in relationships with each other as they operate.

Both the OEM thermostat and the HDS thermostats perform these functions very well. An in-line stat CANNOT perform this function period!!! :roll:

Basic diagram of how a bypass circuit functions:

Science and Energy · **Joined:** Thu Mar 30, 2017 9:12 am **Posts:** 246

OK OK So that won't work.

I wonder if we can get the part number of the actual thermostat inside the housing. If I can get a different temp version of the same dimension (they often have variants identical in all but temperature) perhaps I can TIG or braze the housing back together after it is dissected and re-stuffed carefully.

I am not claiming this is a solution just trying to have group discussion to find a possible solution but trying ideas.

WWDiesel · **Posted:** Fri Mar 31, 2017 2:34 pm

Science and Energy wrote:

OK OK So that won't work.

I wonder if we can get the part number of the actual thermostat inside the housing. If I can get a different temp version of the same dimension (they often have variants identical in all but temperature) perhaps I can TIG or braze the housing back together after it is dissected and re-stuffed carefully.
I am not claiming this is a solution just trying to have group discussion to find a possible solution but trying ideas.

It has been discussed on this forum in great detail many times before. :dizzy:

See this site for modifying your own housing and replacing the OEM stat using an off the shelf thermostat
http://www.jeepkj.com/forum/f228/diy-se ... tat-59804/

Another thread to read on modifying:
viewtopic.php?f=5&t=50940

Both require some machining... :roll:

To me there are only two reasonable options not having a machine shop available, an OEM stat, or the HDS unit... :banghead:

Now if one could find a higher temperature thermostat for a VM engine from an overseas vendor at a reasonable price, that would be wonderful!!!! Many VM motor equipped vehicles in Europe, Africa, Australia, etc... and I bet some of them use a higher temperature thermostat...

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

Science and Energy wrote:

If I did a stock replacement it would still be at the low temp setting right or did mopar up the temp later?
Could someone destroy the thermostat inside the housing and simply install an inline immediately after? Sorta like gut it out. The advantage would be ease of service after and a higher temp setting.

Somebody has done this already, and his jeep overheats.

Look for a PM; I will be sending one to you soon.

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

WWDiesel wrote:

Science and Energy wrote:

If I did a stock replacement it would still be at the low temp setting right or did mopar up the temp later?
Could someone destroy the thermostat inside the housing and simply install an inline immediately after? Sorta like gut it out. The advantage would be ease of service after and a higher temp setting.

An OEM thermostat would still be at the stock temperature. I believe the lower temperature was some kind of stupid emission thing to keep NOX down?

Only problem with using a gutted housing and in-line thermostat; the bypass circuit would be 100% open all the time and that is a straight shot from the housing to the water pump's suction inlet so you would be bypassing 100% all the time. That could cause overheating problems big time!!!

The bypass valve has to be in the circuit and functional at all times for correct engine warming and temperature control.
A fully operational OEM or HDS stat controls the bypass valve and closes it off proportionally while at the same time the main thermostat valve is opening up to send flow through the radiator. As the main thermostat valve opens, the bypass valve closes off and the main valve is open and modulating to control temperature at setpoint. The main valve and the bypass valves opening rates and positions are not fully linear with each other, but rather proportional in relationships with each other as they operate.

Both the OEM thermostat and the HDS thermostats perform these functions very well. An in-line stat CANNOT perform this function period!!! :roll:

Basic diagram of how a bypass circuit functions:

This is one of the best explanations I have ever seen, and I really would like the link to the website that has this diagram. Please.

Yes, the OEM thermostat assembly performs its functions very well, but it is of poor quality and does not last very long. You also have the 176 degree opening temperature thermostat valve in that OEM assembly which runs your engine way too cool for best fuel economy and long term reliability. This valve was specified for North American Liberty CRDs to comply with the E.P.A.'s ridiculous NOx emissions standards. Even the European spec CRDs have an engine thermostat that is a little too cool for ideal operating temperatures.

This is why for the past several years people have been trying to raise the operating temperature of the CRD engine. Most of the ideas people have tried make fundamental changes to how the CRD engine's cooling system functions, and can cause serious problems if used for any reasonable amount of time. A couple of modified thermostats try to imitate the function of the OEM thermostat, but there are serious questions as to whether or not proper coolant flow is maintained, (and, ideally, increased to compensate for running the engine at higher operating temperature), and if the construction of the modified housing will hold up over time.

The Hot Diesel Solutions Model 001 engine thermostat assembly is the only aftermarket upgrade you can count on to function exactly like the O.E. part, but also reliably and safely run your CRD engine at a significantly higher operating temperature. It is also by far the highest quality and strongest option available, with extra features not available with the modified options.

mass-hole · **Posted:** Sat Apr 01, 2017 10:43 am

Dont do an inline. Either get an OE replacement or get an HDS.

Science and Energy · **Joined:** Thu Mar 30, 2017 9:12 am **Posts:** 246

Ug, a bad thermostat or a wonderful one that costs a wonderful amount of money. Neither is a savory prospect.

Mountainman · **Posted:** Mon Apr 03, 2017 11:25 pm

Science and Energy wrote:

Ug, a bad thermostat or a wonderful one that costs a wonderful amount of money. Neither is a savory prospect.

Well, since they fail every 40k or so, it's more like $480ish for a wonderful one, or $100+ plus time and labor every 40k, plus more cash that the HDS would have saved you on fuel, and likely engine life :2cents:

olypopper · **Posted:** Tue Apr 04, 2017 12:16 am

Science and Energy wrote:

Ug, a bad thermostat or a wonderful one that costs a wonderful amount of money. Neither is a savory prospect.

Get over it being expensive. After all the mods I've done on my Jeep (lots) the HDS has been the best. Steady temps and fantastic HEAT!!!

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

Get the HDS001. Based on the cost to do anything to these vehicles, it's really not that bad. If you live in a cold climate, you will love the HDS001 when you turn on your heat. I'm in Colorado, and in the winter, I have heat in a 1/2 mile of driving or so. With the OE stat, even when it is working, it took forever to get heat from the car, and it wasn't really very warm on cold days. Then there's the mileage argument, but as far as I'm concerned, the fast warm up and doing the job once is well worth the cost. Plus the thing is a nicely machined beast once you see it.

Science and Energy · **Joined:** Thu Mar 30, 2017 9:12 am **Posts:** 246

Funny you say that. It was one of the first things I noticed. I turned on the heat and went hmm..... maybe I need to adjust the coolant flow control valve of something. I will give it some serious consideration. The failed rockers and ARP studs are going to cost me though.
Thanks for the heater info. :juggle:

NapaBavarian · **Joined:** Mon Jun 20, 2016 2:39 pm **Posts:** 129

Jeff speaks in third person about himself...

TURBO-DIESEL-FREAK wrote:

WWDiesel wrote:

Science and Energy wrote:

If I did a stock replacement it would still be at the low temp setting right or did mopar up the temp later?
Could someone destroy the thermostat inside the housing and simply install an inline immediately after? Sorta like gut it out. The advantage would be ease of service after and a higher temp setting.

An OEM thermostat would still be at the stock temperature. I believe the lower temperature was some kind of stupid emission thing to keep NOX down?

Only problem with using a gutted housing and in-line thermostat; the bypass circuit would be 100% open all the time and that is a straight shot from the housing to the water pump's suction inlet so you would be bypassing 100% all the time. That could cause overheating problems big time!!!

The bypass valve has to be in the circuit and functional at all times for correct engine warming and temperature control.
A fully operational OEM or HDS stat controls the bypass valve and closes it off proportionally while at the same time the main thermostat valve is opening up to send flow through the radiator. As the main thermostat valve opens, the bypass valve closes off and the main valve is open and modulating to control temperature at setpoint. The main valve and the bypass valves opening rates and positions are not fully linear with each other, but rather proportional in relationships with each other as they operate.

Both the OEM thermostat and the HDS thermostats perform these functions very well. An in-line stat CANNOT perform this function period!!! :roll:

Basic diagram of how a bypass circuit functions:

This is one of the best explanations I have ever seen, and I really would like the link to the website that has this diagram. Please.

Yes, the OEM thermostat assembly performs its functions very well, but it is of poor quality and does not last very long. You also have the 176 degree opening temperature thermostat valve in that OEM assembly which runs your engine way too cool for best fuel economy and long term reliability. This valve was specified for North American Liberty CRDs to comply with the E.P.A.'s ridiculous NOx emissions standards. Even the European spec CRDs have an engine thermostat that is a little too cool for ideal operating temperatures.

This is why for the past several years people have been trying to raise the operating temperature of the CRD engine. Most of the ideas people have tried make fundamental changes to how the CRD engine's cooling system functions, and can cause serious problems if used for any reasonable amount of time. A couple of modified thermostats try to imitate the function of the OEM thermostat, but there are serious questions as to whether or not proper coolant flow is maintained, (and, ideally, increased to compensate for running the engine at higher operating temperature), and if the construction of the modified housing will hold up over time.

The Hot Diesel Solutions Model 001 engine thermostat assembly is the only aftermarket upgrade you can count on to function exactly like the O.E. part, but also reliably and safely run your CRD engine at a significantly higher operating temperature. It is also by far the highest quality and strongest option available, with extra features not available with the modified options.

dh100m · **Posted:** Fri Apr 07, 2017 6:59 am

I have been using my own modified housing with original parts for 2 years on 2 crd s with 195 stant with absolutely no problems if interested pm me for info posted this before but somehow got lost??
regards tony

NapaBavarian · **Joined:** Mon Jun 20, 2016 2:39 pm **Posts:** 129

dh100m wrote:

I have been using my own modified housing with original parts for 2 years on 2 crd s with 195 stant with absolutely no problems if interested pm me for info posted this before but somehow got lost??
regards tony

The welds could fail

Ya know, welding isn't very strong, after all a welded hitch can only support the weight of an 80,000 # semi trailer, or 130psi home air compressor.

The modified thermostat under a few psi could easily blow apart and the forces would easily push it into orbit, you'd better have friends on the space station if you want it back.

[I feel the need to point out this was a sarcastic post in an attempt to point out the strength of this solution, a proper weld won't fail]

flash7210 · **Posted:** Fri Apr 07, 2017 9:15 am

dh100m wrote:

I have been using my own modified housing with original parts for 2 years on 2 crd s with 195 stant with absolutely no problems if interested pm me for info posted this before but somehow got lost??
regards tony

Its not lost: http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=81036

Mountainman · **Posted:** Fri Apr 07, 2017 12:25 pm

dh100m wrote:

I have been using my own modified housing with original parts for 2 years on 2 crd s with 195 stant with absolutely no problems if interested pm me for info posted this before but somehow got lost??
regards tony

Two years is good, but it just takes moments of that thing failing to blast the coolant out and not only kill the head, but melt #1 piston. And the one I got that did that only had the plastic elbow break. So, of you go that route at least make sure to upgrade plastic to brass. I just want something that I'm confident that it will last 20 years :2cents:

Is there a good thermostat solution?

Who is online