B90 Lower Oil Crankshaft Seal

[Yamster90]

New to the forum. Thanks for all current. Are you able to pull the Oil Seal Housing to replace the seals, or do you have to split the Case, Thanks

[99yam40]

full model number may help others figure out what motor you are talking about

[Yamster90]

Yeah, I'm Sorry, It is a 98' B90TLRW. The two lower crankshaft seals inside the seal housing. I am getting water in #3 Cyl. No sign of it coming from the head gasket, or head. A outboard mechanic thought the lower seals are probably the culprit. The manifold seal looked pretty ugly,. Symptoms were, Motor ran fine, then would start to miss, then a smoke/steam would escape from under the front of the cowl. The Plug would then be fouled. Also, after not running for 2 months over the winter, there was a sign of rust on the end of the plug.

[99yam40]

Is there water around that lower crank seal that could be sucked into the crankcase?
I always though that if the crank seal leaked it would let air in or some oil out that settles around that lower seal inside the crankcase.

did you pull the side exhaust cover to inspect that area?

that seal housing shows to have 3 bolts that hold it in place, But I have no idea if there is anything to hook onto to pull it out.
might have to drill holes and tap to pull on and then replace the whole housing.
Does your service manual have any info on pulling it?

[Yamster90]

I'm not sure about the oil/air introduction in that area. I am pretty new to these motors and would love to see a cut away view. I haven't pulled the exhaust cover yet. I had 3 bolts that , in my mind, were about to break, so decided to hold off on the plate until necessary. I'll work on them again and see if they will cooperate. I did notice some rusting inside the end of the splines on the crankshaft.

[TownsendsFJR1300]

Looking at the parts diagram, that seal housing would HAVE TO COME OFF before you could even split cases, so no, you don't have to split cases..

Seals 3 and 4 are oil seals.. I don't think (guessing) water is anywhere near those seals but easy enough to check and replace.

https://www.boats.net/catalog/yamaha...nkshaft-piston

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[TownsendsFJR1300]

Did you pull the head, head gasket and visually inspect?

I would suspect the water issue to be there vs the oil seals..

.

[Yamster90]

I don't mean to be slow responding, I appreciate all of your help, I'm looking back and forth between the manual and parts diagram. I had been trying to get the exhaust cover. No luck yet. I had pulled the seal housing out a little after removing the 3 bolts, it was so clean I thought it was the outer race of the bearing. I believe the shaft and bearing will stay in place and I can pull the housing., The manual talked about aligning the holes of the housing when installing the crankshaft, but never tells you when to tighten the housing bolts. Goes straight from torqueing the crankcase to installing it into the housing. I believe I'm safe to pull the seal housing out. What are your thoughts? thanks

[Yamster90]

I'm still learning how to navigate the forum and missed some of your posts. The head gasket and cover gasket showed no signs of anything creeping between each other,

[Yamster90]

I agree with you Townsend, the housing is coming off.....

[Yamster90]

Housing came right off, they even put a little tab towards the center of the motor to pry it out with a crows foot. Thanks so much for your help gentlemen. I plan on replacing all of the hoses, and go ahead and rebuild the carbs. Is there anything else you would suggest doing while I have it taken down this far. Check the reed valves?

[Yamster90]

A little worn. I guess 23 years, some thing will wear out, Thanks again

[99yam40]

I would not be doing a lot to the motor until you find out where the water is coming from.
if it is a corrosion hole in block, spending money on other stuff is a waste

why is that seal so off center

[Yamster90]

I was holding the camera off center to get the light on the worn part of the seal. The check valve above numeral 6 that Townsend posted appears to be stopped up, Do you know which way the flow is and a estimate on how much pressure it would take to activate. I would assume the flow would be down towards the seal housing

[99yam40]

I think that check valve should be directing the flow away from the housing to suck up condensed fuel and oil from the bottom of the crankcase cavity and sends up to be put back thru the intake to be burned