thermostat Housing Leak

[Whiz]

Hello again, So I finally got around to changing my thermostat.  Now I can not seem to get the housing sealed or when putting the housing on the thermostat is coming out of place.  this was my second attempt, after my first attempt I bought a new housing thinking the old one may have been warped etc.  However, after getting installed last night it is still leaking badly out the side. First time I only used a Gasket (felpro), second time I used the same gasket and Permatex #2.  Any advice, tips or possible things I could be doing wrong?

 

Thanks in Advance.

 

 

[ParadiseMJ]

The problem is that the t-stat can fall out of the recess while you're messing with the housing.  It doesn't have to move much to make the seal...not seal.  To make it water tight, stick the t-stat to the block with some RTV before you put the stat housing back on.  After doing this myself back in the day, and cracking a t-stat housing, I do this:

 

Take the front of the housing off.  Remove the t-stat, remove the gasket.  Clean the two surfaces so that there are no little bits of RTV, sealant etc.  Make sure the same is true with the actual thermostat.  Clean.  Then put a few dabs (small dabs) of RTV on the engine side of the t-stat...about 4-6 small little dabs.  Make sure the block, where the stat goes is dry.  Place the thermostat (spring side IN) in the recessed groove on the block.  Make sure it's seating in the recess on the block.  Secure it there, if need be, with some masking tape...go have a beer, mow the lawn, visit some friends.

 

After about an hour, to be sure, and after the RTV has somewhat set, don't touch it...put a thin layer of RTV on both sides of the gasket, paste it to the housing and carefully cover the t-stat with the cover.  Bottom bolt first, top bolt second.  Do not crank down on those bolts too hard, if the t-stat isn't set it can fall out...just a skosh...and keep it from sealing correctly, If you crank those bolts too hard you can and will crack the housing itself.

 

EDIT: It's a good idea to loosen the serpentine belt to get better access to that bottom bolt.

[Whiz]

Thanks, I will try that this evening!

[Whiz]

So in taking off the housing this time, I drop the bottom bolt, saw it, tried to grab with fingers and it fell again. :doh:  And now I can not see it anywhere. Spent at least 45 mins looking.  How worried should I be where it ended up, should I just get a new bolt or start removing things like the fan so I can see and feel around more for it?  I beleive from research I can use a 5/16" x 1" bolt as a replacement

[HOrnbrod]

Do you have the rubber splash guard under your engine? If so, it'll probably be lying at the lowest sagging point. That's where my dropped hardware usually ends up. And if you can't find it, just replace it. And pick up a telescoping magnetic pickup tool. Handy tool to have for things like this.  :thumbsup:

 

[Whiz]

TY Hornbrod, I got under the truck and saw it, had to go get one of pickup magnets and got the bolt.  Now, I put the housing on, and when I filled up with Anti freeze without even starting the engine I saw it dripping from the bottom of the housing.  Sigh.  My only thought is that since I didnt drain the anti freeze this time, there was a slow drip on the bottom of the opening where the tstat goes in. I wiped it several times but was still a slight drip and I thought nothing of it. But now wonder if that is the cause of the leak now. I did start the engine and it is not spewing out the side like it did before, just a steady drip from the bottom.  Man this thing is kicking my butt!

[ParadiseMJ]

That's why I mentioned it. Water (coolant) and RTV might make a poor seal.  Did you check the housing for cracks?  I had a tiny crack on the inside, but I didn't think it went all the way through...it did.  Just sayin'.

[Whiz]

Yeah, so much for attention to detail.  I did inspect the housing and didnt see any cracks but I will look again this go round.

 

Thanks Again.  

[FrankTheDog]

There is a coolant drain on the side of the block under the manifolds. Drain your coolant out there. Then after you take the thermostat housing off mop up any remaining coolant making sure it is dry and clean. Then I use Permatex tacky gasket in a spray can and lightly coat both metal surfaces and set the gasket on the housing with the bolts holding it in place. Follow the directions on the can, it needs a few minutes of drying time.

The tacky gasket is enough to hold the thermostat in place.

Make sure you use a 195 degree stat with a bleeder in it.

[gogmorgo]

It's probably going to be easier to drain the coolant via the drain C#*@ in the rad. Good luck finding a tool for the block drain...

Edit: drain rooster? Drain willy? I swear that's not a swear word...

[Comavalanche]

It's probably going to be easier to drain the coolant via the drain C#*@ in the rad. Good luck finding a tool for the block drain...

Edit: drain rooster? Drain willy? I swear that's not a swear word...

:rotf: drain rooster haha! Petcock might have worked  ;)

[Minuit]

Those gaskets can be a pain to get to seal. The first time I did it, I had to do it three times. Make sure the mating surface is clean, flat and not cracked. Make sure you torque the bolts evenly but not too tight. Also make sure the thermostat stays in its little slot. If you use sealant, give it some time to cure. I like Permatex High Tack in the spray can. Spray the gasket (on the thermostat housing side) and the thermostat housing fairly generously, let it tack up for about 10 minutes (seriously, let it dry for longer than you think you should. It doesn't really "dry", just gets sticky like paint) and then install the thermostat and housing. Go slowly and make sure you don't let the housing touch anything as you're putting it on.

 

The petcock works great as long as it doesn't break. That probably won't be a problem if it doesn't still have the original radiator. An alternative is to undo the lower radiator hose, but you better be prepared for gallons of coolant spilling out of the engine and radiator in about 5 seconds.

 

I'm surprised so many of you still have your engine splash shield. Mine was torn in half, hid anything I dropped, and was soaked through with oil and coolant. It went away pretty quick :D

[Rockfrog]

Honestly, I've never used a gasket, the key to a good seal is prep. Clean and scrape/sand the block sealing surface, and do the same for the thermostat housing.

Then degrease and dry both surfaces. I usually hit both with Brake Cleaner.

Then I lay a bead of RTV (blue, black, or gray) and smooth it out evenly-ish.

Place thermostat, place housing, and install bolts finger tight. Give the housing a little wiggle and go grab a coffee.

After coffee tighten the bolts to spec. Have another coffee/beer and a snack, about 45 minutes worth.

Fill with coolant and go from there.

Haven't had a leak yet (about 8 installs over 10yrs on 4 different motors).

But I do tend to get a bit anal about the clean and smooth part.

 

Sent from my SGH-I337M using Tapatalk

[Knucklehead97]

I've done it 3 times on two different Jeeps and never had a leak. I just used a Felpro gasket, a thin layer of RTV on both sides to keep it in place, and MAKE SURE to torque the bolts to spec. They can snap and/or crack the housing very easily. I believe it was 13 ft-lbs.

[gogmorgo]

Clean and smooth is the thing to look for, whether you're using RTV or a gasket. If you have had to clean it up a whole bunch (and then probably there are higher and low spots depending on where you've sanded or filed it down and how much material you've removed, and RTV will do a better job of filling in the gaps. But you definitely want to make sure you've got a nice, clean, and flat mounting surface.

I've had great luck with just the gaskets and no RTV whenever I've done a t-stat, but that may be exactly that. Luck.

[Whiz]

:fs1:  Sooooo.... I again installed a new Housing, found the crack in the first new one as yes I over tighten.  Got a new one this morning.. The face on the motor was clean and feels smooth. I used a razer to remove any gasket and rtv left behind. Put it on, made sure I didnt tighten much.  I do not have a torque wrench small enough, but maybe i need to invest. It was clean and smooth, dry and I wiped good with brake cleaner.  Went to hunting land, came back 4 hours later.  Added antifreeze and its dripping from the bottom again without even stating the engine. I used a felpro gasket with a light coat of permatex #2.  Only thing I can guess is the face on the motor is not even? Should I go over it with a file?  I am no mechanic except on computers but I feel I did everything right this last time.  :hmm:  

[gogmorgo]

There's a good chance if it's been leaking badly for a while the leak could have eroded some material from the block. If you've got something with a straight edge you can run it across the surface to check for high or low spots.

As far as actually torquing down the bolts, 13 ft-lbs is barely anything. Pretty well just snug. I've always just gotten them tight with a 1/4" ratchet.

[HOrnbrod]

I'm surprised so many of you still have your engine splash shield. Mine was torn in half, hid anything I dropped, and was soaked through with oil and coolant. It went away pretty quick :D

 

I replaced the original thick felt-like splash guard with the newer thin rubber guard used on 94 and above XJs, p/n 55174736. It's a lot tougher and doesn't sag nearly as much as the old one. I like to keep crap out of the engine compartment and it really helps keeping water off the alternator.

[HOrnbrod]

There's a good chance if it's been leaking badly for a while the leak could have eroded some material from the block. If you've got something with a straight edge you can run it across the surface to check for high or low spots.

As far as actually torquing down the bolts, 13 ft-lbs is barely anything. Pretty well just snug. I've always just gotten them tight with a 1/4" ratchet.

 

That's unlikely but I suppose it's possible over a long period of time. I'd clean both surfaces as directed above, then get some thicker gasket material and make your own gasket using the stat housing as a template. Assemble with a thin even layer of silicon on both sides of the gasket, and let sit at least overnight before adding coolant. This should work for you.

[Minuit]

 

I'm surprised so many of you still have your engine splash shield. Mine was torn in half, hid anything I dropped, and was soaked through with oil and coolant. It went away pretty quick :D

 

I replaced the original thick felt-like splash guard with the newer thin rubber guard used on 94 and above XJs, p/n 55174736. It's a lot tougher and doesn't sag nearly as much as the old one. I like to keep crap out of the engine compartment and it really helps keeping water off the alternator.

 

 

Huh, had no idea the newer version existed. Don't think I've ever seen one still in place other than the one on the '91, ever. Thanks for the p/n, might have to pick one up :thumbsup:

[Whiz]

Thank you all for your Help, no leak on this install.   :bowdown: Very much appreciate it.  However, now my belt is chirping very loudly. My guess is it is from the Anti Freeze leaking on it.  Anything I can do for that, or should I just replace the belt?

[ParadiseMJ]

Check the belt tension, should be good and tight, 165 > on a Krikit II gauge.  The squeal could also be the pulley.

[onlyinajeep726]

It's probably going to be easier to drain the coolant via the drain  in the rad. Good luck finding a tool for the block drain...

Edit: drain rooster? Drain willy? I swear that's not a swear word...

 

Better? Hahaha :rotf:

[Whiz]

Ok, I will check the tension. The pulley is new, as is the water pump and Harmonic balancer. 

[Knucklehead97]

Ok, I will check the tension. The pulley is new, as is the water pump and Harmonic balancer.

when I bought my most recent MJ I had to change the thermostat housing gasket. After I did that, the belt started chirping. No matter how much I tightened the belt it would do it. I've been driving it for months and havn't had a problem. The chirping comes and goes. Still can't find where it's coming from.