Sealant on T-stat housing or not

[aarvig]

What is the general consensus? Should I use a sealant on the thermostat housing gasket or not? I’ve got a Windsor Ford small block And had to put a spacer in between the intake manifold and the “FE” style expansion tank so there will be two gaskets on either side of a spacer. Would you recommend using permatex on the gaskets and T-Stat housing or just using the fiber based gaskets with no sealant.

[NAZ]

I don't run sealant on the coolant system sealing surfaces if they are in good condition and clean, just a gasket. The exception is if I need to glue a gasket to aid assembly I'll use a dab of Ultra Black sealant (works on water as well as oil). Of course if you're dealing with poor mating surfaces a sealant can help ensure a leak free joint.

But if you're using the style of t-stat housing that uses an o-ring, don't use a sealant. Also, a tip for cleaning o-rings if reusing them: use a clean rag with solvent (I use methanol) and PUSH the o-ring through the folded rag, do not pull it through or you will tend to stretch the o-ring.

[tonywy]

I have always had poor luck using no sealant. But,as NAZ said the correct way is no sealant. I always use a thin coat of black RTV take your pick and assemble, do not overtighten. I always try to use an OE tstat housing. And as far as the aftermarket O ring style I could never get them to seal even the expensive ones.