To goop or not to goop...

[BoulderBiker]

I'm doing a rebuild on a 16v GS750ED engine and have heard varying lines on whether to put some kind of silicone between the block and the bottom and and likewise between the block and the head. The Suzuki manual that I have doesn't mention anything of the sort, but I sure don't want to get done with this and have a leaker.

So what's the real scoop from those in the know?

[Dink]

DO NOT USE SILICON SEALANT!!!

Dink

[BoulderBiker]

Just a good cleaning assuring that the mating surfaces are all nice and flat and vesrah gaskets will do the trick eh?

[emjay]

I scrape all the old gasket off then sand the surfaces smooth and clean.

[mark]

With the head and block off my bike now, I can tell you this. The PO of this bike used silicone everywhere on this bike, including head gasket and base gaskets. For certain I can tell you that it did not stop any leaks between the block and case or the block and heads.....just made a mess. I'll never use that stuff again...on my bike at least.

[runrx02]

why no sealant??

[tkent02]

Good gaskets don't need it....

why no sealant??

It will just make it leak, and be very hard to clean off next time.

[argonsagas]

You should not need any type of sealant, as long as the matching faces are clean and clear of any loose debris or old gasket material.

Cleaniliness is VERY important, as there will be pressure under the head and even a tiny bit of dirt will allow a heat expansion that will lift the gasket miscroscopically, and the space will grow until it blows.

Should you use a sealant you can be assured it will deteriorate quickly, and then burn. You will then have to remove the head, but the sealant will almost certainly have burned into place and make a simple job very difficult.

I like copper-faced gaskets and use a bit of oil (finger-wipe) around each hole, top and bottom sides. My theory is that is may reduce the possibility of friction tearing anything when torquing things in place.

Additional tip:
ALWAYS put oil on the cylinder head bolt threads before putting a nut on them. They must be completely clean as well, or you will get an incorrect
torque reading. The bit of oil here reduces friction, and allows a more accurate reading.

[earlfor]

I replaced the head and base gaskets on my 1150 about two years ago. I did not use any kind of sealer, just the gaskets and a little oil wiped with my finger on the mating surfaces. Nothing has, or does leak. If I need a gasket to "stick" in place during assembly, I use a small bit of grease.



Earl

[Billy Ricks]

Should be metal gaskets at both ends, no sealer necessary.

[BoulderBiker]

Great, thanks everyone!

[maddoctor]

Per Clymer & Suzuki: No Sealant or Adhesive of Any Kind

Do NOT, repeat NOT, use any kind of a gasket adhesive unless it is specified by the Suzuki or Clymer manual. In the event of a disagreement between those two sources, go with Suzuki's specifications.

As someone said earlier, cleanliness is the most important thing when reassembling one of these engines. As long as the old gasket is completely removed and the surface is not damaged (gouges, nicks, etc.) the gasket will do the job of sealing the surfaces. Most small scratches or nicks can be polished out with sandpaper if you're worried about them.

Mad Doctor

[bwringer]

I agree that no sealants are needed between clean, flat surfaces. And silicone sealers should never be allowed anywhere near a GS.

Out here in the real world, mating surfaces are usually marred in some way. I've often used a very small amount of Permatex Hylomar non-hardening sealant only in the spots where it's needed, and this has always worked quite well.

Hylomar is a strange bright blue, extremely thick, viscous, sticky goo that never hardens or thins out. It won't cause problems in the engine if you use small amounts, and it won't cause gaskets to stick in the future.

When sanding or otherwise dressing gouges and the like, you have to be very, very careful that you don't create low spots. It's especially easy to do if you're using a Dremel. It's far better to seal a deep gouge with a wee bit of Hylomar than to sand that area aggressively and end up with a low spot, which could leak or cause warping when torqued down.

Very thin dots of Hylomar also work well to stick reluctant gaskets in place during assembly. Not much of a problem on a GS, but commonly needed when working on cars.

[Jethro]

I use the Grey Hylomar on my valve cover gasket becasue the red 1981 Suzuki factory shop manual in the binder says to do so, but I'm not having this fight again.

[BoulderBiker]

that brings up a good question, the manual does state to use sillicone sealer on the valve cover even with the rubber gasket. Is this not necessary? Sure is a pain and a mess doing that with sillicone.