Thermostat gasket leaking AGAIN!!!!

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jfive said:
Thanks, I usually shop around seen it was a little cheaper there already lol. like I said before it has been this long I can wait, i'm cheap, lol :)
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haha i'm the same way... not in a rush anymore..
 
I would check bolt length and see if the manifold bolt holes are clean, especially the bottoms of the holes. Have you checked the manifold itself, maybe take a fine cut flat file and gently surface the manifold area. Check for cracks around the bolt holes and cracks in the housing.
 
With the groove for the stat flange in the neck and not the intake, the gasket goes down first, then the stat and neck. Most likely to leak where the gasket is thin between the bolt holes and come out around the bolt shank, or the stat could be offcenter and pinch between the neck and intake.
 
I didn't even consider that he might be putting the stat on the wrong side of the gasket :)
 
Dicer said:
I would check bolt length and see if the manifold bolt holes are clean, especially the bottoms of the holes. Have you checked the manifold itself, maybe take a fine cut flat file and gently surface the manifold area. Check for cracks around the bolt holes and cracks in the housing.
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i do appreciate all the reply's and help to try and resolve the leak, but i still have not found an answer to "Is the gasket failing?" i can use all the sealer i want but if the gasket sticky surface is removing itself from the gasket it doesn't matter that i used RTV, Aviation, or nothing at all on that side. pardon my drawing but this is what i seen the first time i had the leak.

1721401513129.png



the sealer was stuck to the film on the housing, and the gasket was stuck on the intake. when i removed the bolt i didnt even have to use effort to remove the housing. the gasket was stuck to intake and the film was stuck to the housing, had to scape them both clean again.
MV8 said:
With the groove for the stat flange in the neck and not the intake, the gasket goes down first, then the stat and neck. Most likely to leak where the gasket is thin between the bolt holes and come out around the bolt shank, or the stat could be offcenter and pinch between the neck and intake.
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yes thats how it is.
 
Are you SURE it's leaking at the gasket, and not weeping up through the bolt threads?
Many times the bolt holes are open to the coolant passage and will leak if the threads are not properly sealed. Other possibility is that the bolts are too long for the gasket being used and are bottoming out before they properly torque down the housing.
 
So I saw this on a small block page on FB. Has anyone else tried this thermostat? I ordered and planning to try it in the next week.
1721404532231.png
 
Professor Fate said:
Are you SURE it's leaking at the gasket, and not weeping up through the bolt threads?
Many times the bolt holes are open to the coolant passage and will leak if the threads are not properly sealed. Other possibility is that the bolts are too long for the gasket being used and are bottoming out before they properly torque down the housing.
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well like i said, the first time i took it off the gasket and sticker part was separated so i assumed the gasket failed, but when i got the new gasket from another store it had the same sticker side to it. so when i installed i didn't use sealer on then sticker ( thought that was the issue) now have the leak again. I will remove again this weekend and try to get some pictures of the gasket and see what we all think.

use the aviation sealer on threads as well? what is the proper length for the bolts so i can make sure they aren't to long.

Mopar-Matt said:
So I saw this on a small block page on FB. Has anyone else tried this thermostat? I ordered and planning to try it in the next week. View attachment 1716278119
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interesting.......
 
My thermostat housing story...

EVERY thermostat housing on any engine I have had has leaked.

Untill now!

  1. I bought an OEM style repo housing
  2. I block sanded the intake, still had a ton of old corrosion poc marks
  3. IMPORTANT... I cleaned out the bolt holes in the manifold till the bolts could be screwed in by hand and bottom out on the bolt head / manifold surface.
  4. I bought a gasket from Real gaskets Thermostat Housing Gasket - Chrysler, Dodge, Plymouth - Older V8 Engines
  5. I installed the gasket EXACTLY AS THE INSTRUCTIONS SAID AND TORQUED THE BOLTS TO THE CORRECT INCH POUND SPEC
7+ years not 1 drop and I use a 16lb cap
 
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The Real Gasket worked for me until I installed a Flowkooler pump, blew it out 2 times in a row. Had to clean the engine bay twice. I will take the o-ringed housing every time, no more gasket, no more sealer, no cleaning up the damn mess. No free lunch here, you are going to pay for it with your time, waiting for parts and money, one way or another. Hope it all works out for you.
 
Jfive, set the neck on a cd case black side, hold it up to eye level, then try to shine a flashlight under it toward you. You could also try a small cake pan bottom. Nothing around the house is that wide and perfectly flat but those are kinda close. Can you take and post pictures? It isn't adding up.
 
MV8 said:
Jfive, set the neck on a cd case black side, hold it up to eye level, then try to shine a flashlight under it toward you. You could also try a small cake pan bottom. Nothing around the house is that wide and perfectly flat but those are kinda close. Can you take and post pictures? It isn't adding up.
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will do. I’ll post when I can. Thanks
 
I made a large oak sanding block for a full sheet of 80 grit paper. And I have a pane of glass (flat!) that I racer tape another piece of 80 grit, and 320 grit to.
Block sand the manifold, I sand the thermostat housing on the glass,
Use whichever sealer you like, leak should be gone.

I use the glass/80/320 grit on warped holley main bodies too. Easy to see when they are flat again.
 
I have two chrome thermostat housings that are more than 30 years old that have never leaked a drop. But a couple I bought more recently leaked no matter what gasket cement or other prep I tried. I don't think the chrome is the problem, it's that the recent ones are garbage.
 
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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Is the thermostat housing flat? Put it on a good flat surface and use a light to find out if you can see the light shining through. If bent, you could try sanding it flat again with 80 grit emery, but probably better to get a new housing.
 
To the OP.....listen to Cruze 418... and me. I had the same problem... constant leaks leaks leaks. Then I saw an article IIRC, in Mopar Action magazine. They did a story on your same problem. The CORRECT fix? A guy named Terry in Canada ... (Ontario?) Terry's Auto Lab is the name of his business. He developed
a thermostat housing very similar to the one, that Cruze 418, mentioned in his earlier post.
Billet aluminum housing with the O-RING GASKET! I bought one from Terry for my 360 '71 Duster....and as Cruze said...no more leaks, no more using messy/sticky goop, no more antifreeze cleanup.... just installed it, per the instructions.... and NEVER leaked ever again. Do yourself a huge favor, stop farting around with stock t-stats...get a O-RING style housing and enjoy life.
 
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Icetech said:
probably not.. but if you use that you won't need the o-ring style... the aviation sealer is more a shelac that brushes on, a very thin layer and it 100% will not leak..
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The old brownish almost black with brush works.. I guy I worked with said. ....You could glue brass ball's on a monkey with that stuff.
 
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