Thermostat gasket leaking AGAIN!!!!

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I had the same problem when I installed an Edelbrock Air Gap and a chrome thermostat housing. No matter what I did, it leaked. Then I bought a Billet Specialties polished aluminum part with an O ring. Hasn't leaked a drop in years.
 
I haven't read all the posts, but here is my experience. The ONLY gasket I use is silicon....& never have a leak.

Smooth surfaces like chrome are difficult to seal, no matter what you use. If you use chrome, use coarse sandpaper & sand off the chrome to leave a rough surface.
Using a Dremel with a small carbide tip, I ground a small channel into the gasket surface, on the intake flange & t/stat housing. About 0.020" deep, not critical. This provides an 'anchor' for the silicon.
 
Just Google Flashpower #181491-200 o-ringed thermostat housing, should pop right up.
 
Icetech said:
the 30 kinda surprised me, i was expecting 15
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i got it back together and did the 15lbs that i seen on here the most, but if i need to go tighter is the aviation sealer forgiving enough to torque tighter after it is dry?
i see in my manual it says 30ft-lbs, other folks on here are recommending lighter torque as well, one said make sure to torque the proper inch lbs.....
someone even said they just tighten it and never torqued to a spec.
so i guess what is recommended?
why would the manual say 30ft-lbs if almost everyone on here thinks that is to much?

i would think that ma Mopar would have the correct number being they engineered it.......but maybe it was engineered for different gasket material back then??? just another thought
Dana67Dart said:
That goes with my recommendation to get all the junk out of the hole.

If you put the bolt in the hole and tighten it till it stops turning ( don't tighten too much or you can crack the manifold) measure the distance from the underside of the bolt head to the manifold.

Then measure the thickness of the t stat housing.

The bolt to manifold distance has to be less than the thickness of the t stat housing.
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i cleaned the holes and ran a tap down them to make sure they were all clean, and that gave me a a thread or 2 more i believe.

65TerrorCuda said:
30 ft lbs?! No way in hell I go that tight. Not even half that
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what do you recommend and why?
if that is what the manual says then why would it not be correct?

AND thanks to everyone one here for the info and help, i hadn't thought of a few things that were pretty obvious and basic, but I get stuck in the grind sometime and then get frustrated and overthink/overlook things.
 
jfive said:
why would the manual say 30ft-lbs if almost everyone on here thinks that is to much?
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Because i can guarantee 95% of the people here have never used a torque wrench to tighten that part :) Basically... make it "Tight".. i'm sure it will be fine.. as for re-tightening.. that sealer sets hard so not really... but if you have to it won't hurt to try.. you should be fine though.
 
Icetech said:
Because i can guarantee 95% of the people here have never used a torque wrench to tighten that part :) Basically... make it "Tight".. i'm sure it will be fine.. as for re-tightening.. that sealer sets hard so not really... but if you have to it won't hurt to try.. you should be fine though.
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thanks. i will try to get some fluids in tonight, just depends on weather and other chores.
i will report back and maybe even have a runner next time i post......
 
jfive said:
thanks. i will try to get some fluids in tonight, just depends on weather and other chores.
i will report back and maybe even have a runner next time i post......
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If you put in a new gasket with aviation sealer and it leaks you have the worst luck ever :)
 
A poorly machined aftermarket/Repop housing is usually to blame.. Permatex ultra grey and felpro gasket with either a good used housing, or NOS if you can find 1 is my go-to.
 
jfive said:
Read it takes 24 hour cure time. Got to it yesterday, so maybe by the time I get home today (4pm) it will be ready to hook hose back up and fill.
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Yeah, will see... i'm sure it will be fine :)
 
jfive said:
what do you recommend and why?
if that is what the manual says then why would it not be correct?
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I never torqued it but I'd guess around 10 ft lbs. I maybe go 1/4 turn past finger tight, watching the gasket crush. If it leaks I'll tighten it but it never does.

Reason: If 10 ft lbs won't seal it then 30 won't either and may break the housing. Which is what happened to my oem part. Brand new with everything to spec, flat etc., 30 pounds is believable. No idea why they'd spec that much but I know Ford Ranger bellhousing bolts are torqued to insane levels at the factory.
 
On cast housings they should take the 30Ft-Lb with a cast intake.. aluminum intakes, or aluminum thermostat housings will crack, and pull threads at that torque.





65TerrorCuda said:
I never torqued it but I'd guess around 10 ft lbs. I maybe go 1/4 turn past finger tight, watching the gasket crush. If it leaks I'll tighten it but it never does.

Reason: If 10 ft lbs won't seal it then 30 won't either and may break the housing. Which is what happened to my oem part. Brand new with everything to spec, flat etc., 30 pounds is believable. No idea why they'd spec that much but I know Ford Ranger bellhousing bolts are torqued to insane levels at the factory.
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Bolt size is one aspect of torque spec.

Bigger bolts can take more torque.

Screenshot_20240724-190605.png
 
jfive said:
#5 - - so is the manual not correct in saying ft lbs
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I was referring to:

The Real Gasket gasket is a silicon gasket. You install it dry, no sealers, and torque it to 20 to 25 inch pounds per the gasket manufacturer not the OEM

Screenshot_20240724-191221.png
 
Uncle Bob said:
I've got an o-ring style chrome housing here. Go figure.

I don't remember if it leaked or not. I think I just took it off because it looked like cheap chrome dress up junk to me.
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Billet Specialties 0-Ring dint leak and came in black (or used to offer them black not sure if still do)

AIR1.jpg
 
So I'm late to this party, but here goes. At some point Chrysler switch from cast iron to aluminum thermostat housings. The aluminum ones are terrible for warping and no manner of sanding will fix that. I have found that if you get a replacement housing from NAPA (Dorman 902-3012) it has been that it comes in cast iron with a machined face. Take a magnet when you go to pick up the part. here's a link, look at the picture of the sealing face - https://www.napaonline.com/en/search?text=thermostat housing&referer=v2. I have had great luck with the cast iron units, both with regular gaskets using Ultra Grey permatex and thread sealant, and lately with the silicone Real Gasket ones.
 
ok all, i believe i have success. i have used the aviation sealer and a new FELPRO gasket and all seems to be fine. also cleaned threads out completely, got new bolts and added a washer, tried to cover all the bases here. i do believe the problem was the gasket i was getting. it was thin black gasket with sticky on one side. I DO NOT recommend them. the Felpro gasket was thicker as well, maybe 2x thicker.

dart thermo.jpg



OH, and she's a runner now.
 
CRUZE 418 said:
Get a Flashpower #181491-200. O-ringed housing. This is for the large thermostat. When torquing, we are talking inch lbs, not Foot lbs, 15- 25. Had your same problem, not a anymore.

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I’m having the same issue on my Duster that I just got. Chrome housing just leaks. Reading through this thread, looks like this one is the way to go. Any recommendations on thermostats? I’m not sure what’s in it now, so I figured I’d just replace it.

Also any recommendations for an upper radiator hose and intake bypass hose? Need to replace those as well.
 
jfive said:
1970 Swinger 318

ok so in the process removing and installing the engine i replaced the thermostat and gasket. after getting fluids in i noticed it was leaking, must have dine something wrong.....
so i went and got another gasket pulled it resealed it, re-torqued it, added fluid, now leaking again. I don't even have engine running yet and water/coolant has pooled up on the water pump top, running off intake and a little on the intake. I went with a Felpro both times, not sure of part number off hand, and it had a paper on one side that you peel off and has sticky material on it. the first time i used Permatex on both sides, it leaked so i thought maybe not on the sticky side since it is already something there? when removing it i noticed that the film that was no longer part if the gasket, it appears that the sticker part of the gasket was no longer stuck to the gasket after the water/coolant mix touched it, that's where the leak came from. so i only used Permatex on the one side the second time around, and i am still leaking. with all that being said, what did i do wrong? or was it just a janky gasket both times? any recommended gaskets?

thanks in advance everyone.
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Are the housing bolts bottoming out? Maybe silicone or something else at the bottom of the threaded holes?
 
You can get your hoses at any auto store. I used Robert Shaw for the thermostat, the large one, not the small one. 180 or 195 for temp, I have used both. Correct length allen bolts come with that housing, 15-25 in lbs for torque. No sealer.

20230909_160701.jpg
 
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