Crank seal quetion

[Boyd12]

When assembling an engine, I know you are to put Molykote 111 on the inside of the crank seals. Does anything else anywhere else need to be used to aid in sealing the crank case? I thought I remember someone mentioning it but I cant find the post.Thanks!

 

[mikidymac]

Any grease if fine for the inside of the crank seals to lube for start up.
Outside of the seal should be clean and dry. Cases should be sealed with ThreeBond 1184 or 1211.

 

[Boyd12]

Thank you!
I thought someone recommended MolyKote on the seal edges? to aid in sealing it for the leak down test. Whomever wrote it, if i remember correctly, said they had done it on a number of engines and never had a leak.
I think I may be losing my mind!

 

[Tyman2020]

Only apply moly where the service manual states. Any extra is just asking for a weak point or failure. IMO. Also like mikidymac stated use Threebond 1184 or 1211 for the case.

 

[mikidymac]

The molykote is just to lubricate the seal lip on the crankshaft at startup so it doesn't burn up the seal. Molykote is just the brand seadoo used but any grease is fine.

Do not grease the outer shell of the seals ever.

 

[Boyd12]

Hondabond 4 for the case halves?

 

[mikidymac]

Yes, they are basically the same HondaBond 4, Yamabond, Kawchem, MotoSeal.

 

[GGuillot]

Outside of the seal should be clean and dry.

Really? Dry? it needs something otherwise it can leak.. usually 518 works fine, or TB 1184.

 

[mikidymac]

Really? Dry? it needs something otherwise it can leak.. usually 518 works fine, or TB 1184.

These crank seals should go in with no sealant on the outer rubber casing. That's why they are rubber cased, the rubber is what seals. The only part of the seal that gets anything is grease on the inner surfaces so they don't burn up from a dry start.

 

[GGuillot]

No, that is wrong, the seals go on dry. That's why they are rubber cased, the rubber is what seals. The only part of the seal that gets anything is grease on the inner surfaces so they don't burn up from a dry start.

And I disagree on the case sealing part, it's not 'wrong', you do it your way and others do it their way. I never put a seal on any engine or on a shaft that spins in 'dry', grease on the inner part and sealant on the outer part. BTW - I've built plenty engines and not just these jet ski engines, your opinion is noted...but I will respectfully ignore this advice..

 

[mikidymac]

If it makes you feel better I changed the "wrong". What I am saying is that these crank seals in particular do not get sealant around their outer diameter. They are made to go on without sealant and is why they have an outer rubber casing. This is how all of the watercraft crank seals are made, Yamaha, Kawasaki, Fuji, Seadoo. If you want to add sealant that is up to you but not how the manufacturers or other engine builders do it and it is not necessary to seal. The seals are already compressed to seal when you tighten the cases as their OD is larger than the case ID so any additional sealant could change how they compress.

 

[GGuillot]

This is how all of the watercraft crank seals are made, Yamaha, Kawasaki, Fuji, Seadoo.

And same thing in the automotive world, cam seals, crankshaft seals, driveshaft seals, transmission input shaft seals, etc. Rubberized on the outside....and builders still use a sealant against the case during assembly. Not sure why you wouldn't on a jet ski engine..

It's an extra measure or piece of mind, that's all, it doesn't hurt one bit... It might not be a manufacturing process, but it's an assembly technique that's widely applied..

 

[mikidymac]

And same thing in the automotive world, cam seals, crankshaft seals, driveshaft seals, transmission input shaft seals, etc. Rubberized on the outside....and builders still use a sealant against the case during assembly. Not sure why you wouldn't on a jet ski engine..

It's an extra measure or piece of mind, that's all, it doesn't hurt one bit... It might not be a manufacturing process, but it's an assembly technique that's widely applied..

As you said, we can agree to disagree. Carry on.

 

[POPPS]

I'm 100% with miki on this one, there is only so much space between the case and the seal,,,I used to put sealer on the seals of the balancer, and the seals became mushy and leaked,,,so now my mating surfaces are absolutely dry,,,but I put some lub on the inner crank seal for the initial startup.