Technical Chronic water leak - how would you fix it?

Hey Y'all. My 1950 Ford Crestliner is running a 1965 Chevy 396 and an Edelbrock square bore aluminum intake. There has always been a bit of 'seepage' on the back side of where the thermostat housing mounts onto the intake manifold. Nothing major, coolant just puddles in the valley in front of the carb. Due to several health issues the car has sat for longer than it should have but I am now freshening it up and getting it ready to use, but I want this dang leak to stop..
Here's where I am at- I faced the thermostat housing on a 6" wide belt sander. It would take a machine shop to make it any flatter. The area where the housing bolts down is fairly closed in, but I took the glass out of a 4 x 6 picture frame (verified it was flat) and laid it across the opening and pressed down over the 2 bolt holes. I used a feeler gauge to check between the glass and the front area between the bolt holes and could not find a gap. When I did the same thing to the rear area, I could easily get a .004" feeler between them.
So ok, the intake manifold mounting surface appears to not be flat...and the point of this post - how would you go about making the thermostat housing mounting boss flat? There isn't much room to work with in there.
Thoughts and suggestions?

 

Best bet would be pull the intake and machine it.

 

Chronic water leak ? Depends

Pulling the manifold is one solution I’m not sure if there is any gasket material or gasket + sealer that will address the situation without machining.

 

If it's a chrome plated pot metal housing, I'd toss it in favor of a new cast iron or aluminum housing, then just bolt it on with aviation sealer on both sides of the new felpro gasket. I would also carefully inspect the clamp and hose, and make sure to tighten the hose with a 1/4" drive ratchet, not just a screwdriver or nutdriver.


If it's already an iron or aluminum housing, with the gasket and hose set up as described, then I'd consider milling the manifold surface.

 

I had the same problem, faced off the housing (like you have done) and cut a rubber gasket out of an inner tube..
Been leak free for quite a number of years now..

 

If you want something fast and easy put copper Bars Leak in it.

 

Also , make sure the bolts aren't too long and bottoming out.

 

You might try using a file,,,,,cut down to the right size to fit .
It will usually be high around a bolt hole anyway,,,,,it won’t be the entire surface that is out .
Just a few strokes here and there,,,,,,don’t remake the opening .
You can blue it up,,,,,,and file a little,,,,,,just like blocking primer .
It will show the high spots and low spots .
An old file will work okay,,,,you don’t have to destroy a new one,,,,,,we all have several laying around usually,,,LoL .
Get it close,,, and then good sealer like has been recommended,,,,,it should be done after that .
Like Jim said,,,,,,if it is a chrome one,,,,,toss it,, or live with the leak .

Tommy

 

This one place on an engine where chrome don't go. If you're not using a stock housing, get one. Otherwise, as said, it's the intake.

 

Just a teaspoon of pepper and BAM! Leak is gone

 

I've had good luck with Permatex Ultra Copper. Doesn't take gobs, just a good bead that will squish. It even sealed a couple of those chrome necks.

 

I would buy a thermostat housing with a o ring instead of a gasket.

 

Get thick gasket paper and sealant in both side of the gasket paper and torque down.

only way I could see getting the intake flat would be to remove it from the engine .

 

I usually file the manifold to assure it is flat first. I usually use aluminum chevy T housings and to make sure it is flat I take a 180 DA sanding disc, peel the backing off, stick it to a flat surface like a work bench or the floor and sand the housing flat. New gaskets and some RTV and no leaks.

 

Permatex #2. Let it get a little tacky. Both sides of the gasket.

 

.004 ? You worried about .004.. Do what Squirrel said.

 

I would pull the studs out of the intake manifold. Then take a flat heavy piece of steel and a piece of stickie back sandpaper and make the manifold flat, put the studs back in, new gasket, and leak fixed.

 

Use a good quality soft gasket and sealant. Don't over-torque and distort it. Whatever sealant you decide to use... let it cure for at least 24 hours before you fill/pressurize the system.

 

On older aluminum intakes that had a small, weeping issue like your's, I have used an OEM thermostat
housing, normally cast iron, and TWO quality gaskets with a good sealer between the gaskets as well as
on both mating sides. Additionally, after installation, I wait 24hrs to fill with antifreeze. Never had an
issue after that.

 

Thanks fellas- lots of good juice in here. So, here's where I'm headed. blue the intake, use a flat steel plate w/sticky-back sand paper and carefully flatten the intake boss. I have an old aluminum housing and have blue'd and surfaced the bottom- it IS flat. Will use 1 new gasket, then install with sealant on both sides, torque the bolts and wait 24 hrs before filling. w/coolant. If anything throws a red flag- yell out. Thank y'all again- much appreciated.

 

Please post the results.
Thanks.

 

copper gasket and Permatex

 

Black #2 is really good stuff

 

These work pretty good-- https://www.amazon.com/GSKMOTOR-The...cphy=1020569&hvtargid=pla-1028369693420&psc=1

 

egads- that is exactly the gasket that is currently leaking it's butt off on me.

 

Aluminum intake- are you sure it is leaking from there, or do you have a porous casting?

4 mils isn't a huge mismatch...make sure there's no raised areas around the studs, maybe previous owner pulled up some material/warped it trying to over tighten. So the pulled up part around the threads might be preventing the housing from seating properly. A flat file can knock those areas down. Or, chamfer the mounting holes a bit. So the housing can fit over the raised part.

If the material around the studs seems flat, I'd use the Great stuff sealer: degrease!, assemble the gasket and apply Grey to both sides, then tighten it half way. Next day when the grey stuff has set up I'd do the final torquing , which is now compressing the set-up rubbery grey material.

There's a bigger gap than 4 thou on the water passages area: head-to-intake on a FE 390, and those can be sealed up just fine.

 

Look very closely around the two bolt holes for the T stat housing! I've discovered hairline cracks at those two holes and when you tighten bolts into them, and the engine gets hot they seep coolant.
I've never found a good T stat housing that wouldn't seal with a gasket and black RTV on both sides, if there's no cracking. Use thread sealer on the two bolts also, as they go into the coolant passages.

 

Best thing to ever take place , toss the chrome housings as suggested . It will save everyone tons of grief down the road , sooner or later they all will leak . Not worth the time to buy and install one for the rate of return .

 

Buy a housing with o ring...do not over tighten.

 

I had a similar problem with a seeping leak at the thermostat outlet housing. After many attempts to stop it, without luck, I doubled up on the gaskets and applied Permatex Indian Head Shellac to all the surfaces. Tightened up the bolts and let it set for 24 hours. Problem fixed.