I was in the middle of replacing my thermostat a couple weeks ago, when I realized I had the wrong t-stat (for the 4.0 instead of the 4.2).

So, it could not be swapped at the time.

What I did notice, was the existing t-stat is held into the housing on two of its 'tabs', like spring tensioned against them. I tried to wiggle it free, but it was pretty adamant to stay on there. Does it just twist out of this position to release? I don't want to break my housing...its plastic after all.

 

What are you working on? The 4.0 t-stat is like a normal one. The 4.2 comes in pieces and so over engineered it's scary.

 

I've got the 2-piece unit. 4.2L version...trust me, I looked at fitting my 4.0 t-stat and there was no way it would fit.

 

You are correct. Not interchangeable.

It's a goofy set up. I've sold more housings to shops that don't want to mess with the thing. I'm not sure how it works. If anyone can figure it out, you can.

Keep me posted. I'm curious as to what you find.

 

LOL, great, better keep a housing in stock (more like on your desk) in case I break mine trying to get this puppy out.

 

I would suggest you get rid of the plastic POS while you are in there and not worry about it anymore. Mine was cracked when I got in there and I feel much better about the aluminum one. In fact I feel "warm and toasty inside" knowing it is no longer an issue an never will be again. Bring on the next problem!!!

 

I didn't think the 4.2 liter engines had a plastic thermostat. If I'm mistaken, please let me know. I might go ahead and change mine just to prevent future problems. The same goes for the water pump.

 

not avail. Different design(still very prone to cracking)
Matt, push in on the t stat to compress the spring with your palm and twist at the same time to remove. reverse to assemble. pay attention to how its puts together before you remove. a better choice would be to buy the t stat assembled into the hose barb part that you remove.(Ive already been seeing those little tabs break during use) Not the whole housing assembly(yet) or you can buy the housing and remove the neck and just install the crossover pipe t stat assembly(they crack along the top of the crossover pipe)

 

^ appreciate it brutal, will be careful. I've been delaying the replacement, waiting on my octopus heater hose assembly to arrive, its a-leakin coolant quite a bit. I only want to drain the system once, got that upper hose that's 'ballooning' on me too...that's coming off. Wish me luck!

 

Good luck!!

 

Hey H2o,

did you notice a coolant smell before you found the leaking hoses, or were you just in there when you noticed it? I ask because I replaced the cracked thermostat housing and all was fine for about 2k miles now I'm getting a coolant smell and I had to put a pint of coolant in per 1k miles. Now I can't seem to find the leak... The plugs are normal, the oils clean and there's no smoke or smell from the exhaust so I have ruled out head-gasket but I know there's a maze of hoses that tend to go bad under there....

 

I get the drips, only a slight smell sitting at stop signs or lights, and it was easy to spot squirrel during idling in my garage. There are several more clamped locations on that heater hose octopus, so you should be able to locate it if its there.

Next drive, upon stopping (hopefully at home), let it idle and start snooping, best advice I can give.

 

Hey! Squirrel, you never going to get that car fixed!

The simple answer to the never ending coolant leaks is a pressure tester. Available at your friendly, neighborhood local auto parts store. Could never find mine, pumped it up and a super fine mist emulated from the side of the overflow reservoir. Done.

tp

 

I may never get it fixed but I will certainly share my knowledge with others so that they have a chance in hell of getting theirs fixed!!

Good call on the pressure tester BTW!

 

I've ocassionaly experienced a similar problem on long drives

 

New question on same issue. I have just purchased a new thermostat, however, it did not come with any gaskets??? Autozone looked it up and I would have to buy the upper hoses for something that looks like a gasket? Do i need a gasket? Or do i have to invest $80 more ( after $40 for the thermostat) for the upper hose system.

Thanks in advance!!

 

gasket should come with the new thermostat, check to make sure its not somewhat attached to the piece already.

 

The box ONLY had the thermostat in it. Now what?? What about using a gasket making kit or the gasket in a TUBE crap?

 

I presume your thermostat did not come from Jaguar or a UK supplier (Jagbits)?

I just donated a new 4.0L t-stat I was trying to sell. Check out this link, does yours look like this (black rubber is the o-ring in question)

 

Nope.. does not look like that. Is that what I need then???