I am replacing the rear main seal with a 2 piece neoprene job and looking at the FSM. It calls for some type of sealant on thr main caps themselves. What is this and do I need it?

Also other kinda related question; plastigauge measures between .003 and .004. Leave it alone and button it back?

 

you should use a dab of rtv at the joining areas of the rear seals to help prevent a leak and also offset the seals in the block about a 1/4 inch

 

.003 - .004 on rear bearing 5 is ok....on the others thats a little loose but not terrible there is more of a risk of failure at that higher number on 1-4

 

I recommend some sealer OTHER than RTV which can and does ooze out and make strings that break off and go elsewhere.

Form-a-Gasket #2 non-hardening
Permatex 3H aviation sealer
Yamabond at your Yamaha dealer

are some good choices.

 

i will agree there are other sealants you can use as above... rtv is sometimes tricky to use you want a thin consistent one piece bead....not blobs of it that can shred

 

Great info, thanks. And just to be clear, I am not talking about a dab of RTV on the ends of the neoprene seal. I know I need that. It seemed like the fsm wanted some sort of sealant on at least a portion of the mating surface of the cap/block itself.

 

yes i was also referring to that also ....running a bead down each side of the ridge in the block side to completely seal the cap

 

You're talking about the sealing surface between the #5 main bearing cap and the oil pan, right?

Because, just to be clear, there is no sealant used between the bearing caps and the block, or between the oil pump and the bearing cap.

- Eric

 

 

that sealer is similar to the aviation permatex ....that is the ridge i was referring to ( on the block) i just happen to use a bead of rtv along both sides as in the pic

 

You mention a ridge; I see a little valley on the cap that is also pictured in the FSM. Is that what you mean? It ison either sideof what I'm guessing is where the thrust collar rides. It looked like there was some type of sealant in there when I pulled the cap and I have since cleanedit out with a razor.

 

Ok ridge is confusing i bead the area on far rear lenghth of the block
where the cap butts to the block the bead starts at the seal end and back a little then across