Fel-Pro T'stat Housing Gasket Wicking Itself to Death
 

On my last couple of engine builds I used the blue paper t'stat housing gasket that comes in a Fel-Pro engine gasket kit, and in both cases coolant wicked through the gasket and left a little pool on the valley cover. Upon removing the housings, the gaskets were soaked solid and literally fell apart in my hands. I don't understand what has changed and/or why Fel-Pro wouldn't use a material that resists self-wicking, but it is what it is I guess. I don't plan to use anymore of those again.

Has anyone found a gasket that doesn't wick and bleed out?

I see Butler has a gasket that looks like the original shape of a GM gasket (I have one NOS gasket of that shape and it is made of a waxy dark brown paper material). I'll call them tomorrow and ask about that one.

Any other recommendations would be welcomed.

Used both. The butler gasket wicked, too. Not sure what it is about the thermostat housing gaskets.

I eventually just used a 1/8" bead of straight RTV w/ no gasket (Permatex has a purpose-made Waterpump and Thermostat Housing RTV), which is what the factory service manual even recommends doing for my car. Not a drop since.

You can use a thin layer of gasket sealer/maker to stop wicking on the paper type gaskets, thin bead of ultra black or grey spread out with your finger on both sides.

Ive been using the chrome T-stat housings with an O-ring for 20+ years that work great, no leaks and can be reused many times. If/when the oring flattens out, just buy a new one at a hardware store for a dollar. Might not look factory correct but for many cars with chrome/aluminum parts, factory correct doesnt matter.

RTV sealer works great if you give it plenty of time to dry. Not just a few hours.

This is what I do. Very thin film of Ultra Black RTV on both sides of the paper gasket. Zero leaks, zero seeping or sweating.

I used Optimum Gray on both times I tried paper gaskets and it weeped. I doubt it was the different kind of RTV I used, so I guess maybe my mating surfaces have too much pitting? Didn't look like it last time I had it all apart but I still use the original cast iron intake and 'stat aluminum housing.

I too use the chrome neck with an o ring. I believe I tried RTV in the past on the paper gasket. The chrome isn’t my favorite looking (although not that bad) but it has sealed the best and as mentioned is reusable.

The right stuff spread out with your finger.... done start it up. I noticed this too.

What is optimum gray? The permatex ultra grey/black sealers work very well to stop any type of seeping or leaks in coolant or oil applications. If its spread thin over the whole gasket surface & not just a small bead and allowed to fully cure, it literally seals the gasket & should stop any leaks or seepage. Unless there is major pitting that the sealer isnt filling, but even then on pitted timing covers if you fill the pits with the sealer it has always been leak free in my experiences.

Helps to use a sanding block on the intake and lap the housing on something flat. If both surfaces are flat and smooth you get a good squeeze on the gasket. And of course don't over tighten the housing, the ears will bend and it will always seep.

I just bought a batch of the thin blue Felpro gaskets have a few of the black ones left you get from the usual Pontiac shops they are like a sponge.

Thanks for all the replies.

I'm going to finish the two builds I'm working on with just RTV, no t'stat housing gaskets this time, and I'll see how that does. I'm a sucker for good advertising so I'll try the Permatex 22071 pump & stat RTV.

Thanks again all.

Yep, like I said that's how the service manual usually recommends doing it. A 1/8" bead on the gasket surface to resemble an O-Ring usually works just fine, just make sure to only hand tighten down the the bolts and let the RTV cure for an hour before torquing to spec.

I use these teflon gaskets on my intake crossover and water neck housing…works like a charm

https://tinindianperformance.com/Pon...%20Gaskets.htm