bad thermostat

CRD05il · **Posted:** Sat Nov 12, 2011 12:53 pm

how do you tell if a thermostat is bad? I believe mine is bad the dealer said it's perfectly fine but it just go past the quarter of mark. they said they would fix it under the warranty if they could figure out if it was bad.

papaindigo · **Posted:** Sat Nov 12, 2011 1:49 pm

The dealer is an idiot and full of horse digestive by products and apparently so incompetant that they cannot even shoot the tstat housing with an infrared thermometer to demonstrate that the tstat has failed "open" (actually failing due to opening too soon) and the engine is running cold (e.g. below 176F). Go to http://www.greendieselengineering.com/f ... st/19.page first post for an illustration of the temp gauge readings. With a properly functioning tstat the needle should sit almost dead vertical or about 1 needle width left of vertical.

Our tstats work somewhat backwards to normal in that when the tstat is closed coolant flow is thru the bypass to, I believe, the EGR and on to the engine and thru the viscous heater to the cab heater core; as the tstat opens the bypass is closed off and a major portion of the coolant flow goes to the radiator. If the tstat spring gets weak, which typically happens in the 40-50k range (mine and stoutdog's went at about 40K), the bypass gets closed too early and since diesels tend to run cold the radiator essentially over cools the engine and you never reach operating temp. This failure often occurs gradually and is not that noticable in warm weather like summer down here or with the AC running or when towing as those put enough load on the engine that it will get to operating temp but as soon as the weather cools and you quit running AC the temp gauge needle will hang a couple of ticks left of center and gradually drop to just above 1/4 as the tstat gets worse. Lots of discussion of this on the forum.

In a fit of fairness to your dealer it's possible that the temp gauge sending unit is bad but I would not put a plugged nickel bet on that. Bottom line is your tstat needs replacing. Don't know what kind of warranty you have but a new tstat with gasket can be had for about $110 and is about a 45 minute job to install if you are handy (drop me an email if you decide to DIY and want helpful hints on how)

FYI if you have not already done so check out Sam's NOOB guide for lots of useful information and links.

CRD05il · **Posted:** Sat Nov 12, 2011 4:45 pm

I still have the 7/70,000 powertrain warranty for 500 more miles.

papaindigo · **Posted:** Sat Nov 12, 2011 4:53 pm

Should be a free replacement then so push them on it although to be honest I have the same warranty with like 9 months and 30k miles left and I did a DIY replacement just because I trusted me better than the dealer unless I could get past the "wonderful" service writers.

CRD05il · **Posted:** Sat Nov 12, 2011 5:48 pm

They just order me a new turbo because mine was leaking. But they said they would look in to my thermostat. I have to wait a week for a new turbo because they need to order the part. So i don't know how much pushing I can do. But i will bring it up again when i go back for the turbo to be put in.

papaindigo · **Posted:** Sat Nov 12, 2011 6:09 pm

Worst case is they won't do it and I'd be happy with just a new turbo. If that happens the tstat parts are not too expensive and it's an easy DIY and I can provide instructions. Alternatively you might want to consider the inline tstat replacement (Meziere WN0072 housing and 195F Chev tstat with 1/8" hole drilled in skirt) see discussion at viewtopic.php?f=5&t=63264 and viewtopic.php?f=5&t=63587 seems to be working well for folks

Joe Romas · **Posted:** Sat Nov 12, 2011 6:55 pm

I have the Gold or whatever the best warranty Chrysler offered and it's 7/70 also :SOMBRERO:

There's a $100 deductable on each trip. When my thermostat went bad it cost as I remember $104 plus shipping online. I asked the dealer how much more to replace the antifreeze and he was offering to flush my cooling system for an additional $500 while they were replacing the thermostat :dizzy:

So for around $150 I replaced the thermostat and completly drained the coolant and replaced it too :goink:

CRD05il · **Posted:** Sun Nov 13, 2011 12:16 am

I just have the normal powertrain warranty that came with the truck. I just became the 2nd owner of the truck. I am lucky I did not listen to everyone and paid for the warranty to be transferred. I just had 7000 miles and 1 year left on it when I got the jeep in August. If I got the thermostat fix now it would not cost anything extra because I have to pay my 100 dollar deductible because i am getting a new turbo. But i just need something to proven it's broken?

bad thermostat

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