awork

I have a 97 Jeep cherokee with the 4.0. I have recently changed the thermostat on the jeep and had an issue with the gasket sealing up. I went through three gaskets and decided it must be an issue with the thermostat housing so i replaced it. My leak stopped after that. I went and drove it around for awhile and no leaks. A day or two later after driving it i noticed it was leaking again. It doesn't appear to be coming from the thermostat housing this time. There appeared to be a little bit of coolant on the top of the water pump but not much. It is dripping down and leaking off of the steering compontents and near the bottom/front of the engine. I didn't have much of a chance to look at it today but plan on doing more tomorrow.
Would this be a bad water pump or something else? I couldn't see any hoses that are bad either. also i have put a lot of now antifreeze in it and the stuff leaking out was obviously the old stuff because it was pretty nasty looking..

Any help would be appreciated!

Roler

The bit of coolant on top of the waterpump comes from higher up.
If your waterpump goes bad, the coolant will come out of the so-called wheep-hole. This usually doesn't leak at a very fast rate.
The coolant all over the steering and front/bottom on engine, can be coming from the front (radiator leaking). When you drive, the coolant gets blown backwards, ending up on weird places.

The coolant, you mentioned it looked pretty nasty.....as in : milkshake/oily?
When you take the radiator cap off, what does it look like inside?
And when you remove the oil (yes oil) filler cap, is there any crud on the underside of the cap, or inside the engine

If you have unexplained coolant loss, that could mean more costly issues than explained/visible coolant loss...

awork

the coolant doesn't look like it has oil in it, just dirty from being in the radiator. It leaked out a lot after i got home this morning. I would say probably close to half a gallon leaked out. It is dripping down from around the very bottom pully at the bottom of the engine. it also looks like some was coming out from around the thermostat housing. I am unsure how it is still leaking from there, i had went through several gaskets and replaced the housing. I made sure the surface was clean and didnt' over tighten the bolts. The coolant from around there coming out was green (new coolant) what was dripping off of the lower part of the engine still looked like the older coolant. I have no idea where it would be coming from, what was leaking at the t-stat housing was a small amount.

Firestorm500

Did you let it freeze and bust?

awork

Let the engine freeze? It has always had a good mixture of antifreeze and sits in a garage most of the time.

Firehawk068

You have stated that you are going through a bunch of thermostat gaskets?


How exactly are you installing them?


I honestly have only had to re-install a thermostat housing one time..............many years ago, on a Pontiac engine. I had accidentally left a small piece of the old gasket material on the intake manifold, that I didn't scrape/clean completely.......(Lesson learned, and it never happened again)


That being said..................The 4.0 engine does have a slight trick to it.....
The thermostat fits into a shallow, recessed groove in the cylinder head, and MUST remain in-place in this groove while you are installing the thermostat housing over the top of it...............Being that this surface is vertical, if the thermostat slips down (out of the groove) even the slightest bit, then the housing won't sit flush with the head, and will not seal.
You have to be careful when you are putting the housing on, that you don't accidentally bump the thermostat............


First you have to make sure both the cylinder head, and thermostat housing surfaces are completely clean.............Make sure there are no traces of old gasket material or sealant on there............
Inspect them carefully to make sure there is no corrosion pitting on the sealing surfaces...................You may need a new thermostat housing if it is pitted..........Check to make sure it is flat, and not warped.......


Next, make sure you have a good paper thermostat gasket.... (the earlier 4.0 engines used paper only. the later 4.0s used a paper gasket with a printed sealing ring on it) Then, use a proper gasket sealant on both sides of the gasket.................Use a thin film only.......


DO NOT, under any circumstance, use an RTV silicone on the gasket (or ANY gasket for that matter)


**********I know there are a bunch of people who wrongfully use it all the time, and I'll probably get flamed for saying it************


RTV silicones do not work well with gaskets, and are not designed to be used with gaskets............................They are to be used ONLY if you are NOT using a gasket..........( for example: on a diff cover, or an oil pan, or a transmission pan, or even a valve cover..............With NO gasket)
It has been my experience that RTV silicones don't work very well in an environment that is subject to pressure. (even the relatively low pressure of a cooling system)
There is a difference between a "Gasket Sealant", and a "Gasket Maker"..............................Use the proper gasket sealant...................


USE THESE..........................



NOT THIS (or Blue, or Red, or Copper)





Then after you have made contact (thermostat housing to head), hold it in place while you snug the bolts up with your fingers.............


Then properly tighten the bolts........... (if you don't have a lot of experience with wrenching, to have a good feel of what is properly tight with a hand wrench, without being too loose or over tight, then use a torque wrench)


Last, inspect your hoses before you reconnect them.
Make sure they don't have any cracks or pinholes that could leak coolant.......


If you have followed these steps, you should never have an issue of your thermostat gasket leaking, and having to re-do it a bunch of times....

awork

The time before I this I used the same sealant that you have pictured, I put a small dot on the thermostat to hold it in place. It was completely seated in the groove. I put a small amount on both sides of the gasket also, but it was still leaking. This time I decided to go with a new t-stat housing. it was a thick paper gasket that came with it. I made sure the thermostat stayed in place while I put it on ( I could see it through one of the holes in the house). I drove it for a day or two and it didn't leak. I had this same issue last time, it wasn't leaking at first then started after awhile. It seems like once the pressure builds is when it starts. I can't be for sure when looking if its coming from the t-stat housing this time or not. It appeared that a little was and it appeared to be new coolant. But also some dripping from down lower was older coolant. It pours out enough that its constantly dripping when I have it running but when I looked today I was still unable to tell where it was coming from.
What way does the thermostat go in? Does the part that opens on the outside need to be vertical or horizontal? I am not sure if that matters but I had it vertical last time and this time I put it horizontal. This weekend I plan on taking the housing off again and inspecting it. I may try a new gasket and some sealant again to see if that stops it.
I will also try cleaning it off and try to find for sure where the leak is coming from.

Firehawk068

The OEM style thermostat for the 4.0 has a little bleed hole, sometimes with a little "Jiggle Valve" in the hole...............
This should be oriented to be at the top when you seat the thermostat in the groove.................

The part that looks like a round copper cylinder always goes inside the engine.................It is filled with a very special mixture of wax that expands at a specific rate when heated...It pushes the piston that is attached to the little metal rod..............Since the rod can't move (it's wedged into the bridge) the copper cylinder actually moves (it's attached to the valve) and opens the thermostat........

Also, paper gaskets need to be properly "Compressed" to work properly....................It is possible that you didn't tighten it down enough..........
What happens if you don't, is that the paper will just soak through with water/coolant from the inside out, and start to weep coolant.........

Firestorm500

That's a good point between gasket sealer and gasket maker.

I'm sure I have grabbed the RTV before to put in a thermostat. Using a thin film to help hold everything in place.

awork

I will check to confirm i have the thermostat in the right way when i take it out. Also when I first put the new gasket on i didn't have the bolts tightened enough and it was leaking a small amount, i tightened them after that. Could that possibly be a reason why It is leaking?

awork

Does the t-stat go on just like that into the motor?

Firehawk068

I don't see a bleed hole on the flange anywhere (some brands have them, some do not.....)
OE had one on there I believe..............
Your orientation looks fine...................If there is no bleed hole, it wouldn't matter which way it was turned.........

bigbadon

Also Permatex indian shellac is good for hoses and gaskets. The 3 that you have shown could've saved the Titanic!

Firestorm500

Yes. Pellet towards the engine.