Rebuild: when to use gasket sealant

[bran100]

I'm about to put my engine back together. When, if ever, should I use sealant in addition to all the new gaskets? All sealing surfaces appear to be in good condition.

[Tobi]

Cool, I was about to ask the same question.

[BEEK]

the biggest issue with sealant is most people use the wrong kind and way too much. silicone gasket sealant comes in many flavors, all have their place. but when over used they become dangerous inside an engine.

some oem's use silicone from the factory instead of gaskets. honda in particular. "hondabond" is a particular silicone sealant that i would use on paper gaskets or when there is no gasket at all. permatex ultra grey is very close to that.

in the corners of oil pan gaskets where they meet seal plates, a very light amount can be used.

fiat machines all their parts real well from the factory. i use coppercoat on lower cam housing gaskets. this is a spray on sealant that helps the gasket stick and helps leaks there, fiat is known for leakage in this area. this is my opinion. i am sure others have theirs. but in 1000's of applications, i find that this works best unless you have guy crofts special gaskets. but those have silicone sealant built in.

so in a fiat 124 application, when i build an engine this is what i use and where:
lower cam housing gaskets, coppercoat spray
valve cover gaskets, none
head gasket, none, unless using a graphite gasket, then i use coppercoat
cam end housing gaskets, none, but one could use a very light coat of ultra grey there if you want
manifold gaskets, none
oil pan gasket, none, but when replacing in the car i use yellow weatherstrip adhesive to stick the pan gasket to the pan. for ease of installation. when building an engine in the shop, i use a small dab on the corners at the seal plates. if the seal plate gaskets are paper i use a very light coat of ultra grey on them.
the seals themselves, i use a small amount of ultra grey on the outside of the seal when fitting in the housing, then wipe off any extra. i also grease the insides of the seals when installing, this helps not ruining the seal from dry application.
water pump gaskets, a very light coat of ultra grey on the paper gasket, you could use blue silicone here, but you wont find a tube of that stuff in my shop anywhere.

i have used ultra red and ultra copper, in exhaust applications on small block chevrolet race engines where the headers meet the head. and no gasket at all. it holds up real well there.

[bran100]

Good stuff Beek. Thanks

[White78]

I found it curious that the Hanes manual tells you to use grease on a lot of parts. I though it was odd, but it offered enough tack.

[jlw35]

What about the Intake Manifold ( the one the carb sits on?)

thanks
Jeff

[131]

I found it curious that the Hanes manual tells you to use grease on a lot of parts. I though it was odd, but it offered enough tack.

Another reason why the Haynes manual is not a good reference.

[White78]

I found it curious that the Hanes manual tells you to use grease on a lot of parts. I though it was odd, but it offered enough tack.

Another reason why the Haynes manual is not a good reference.

Hmmm, thats not very reassuring considering I followed that to the letter.