Yanmar rear oil seal -- choice of gasket sealant, grease

[sailoppopotamus]

I'm in the process of tearing the engine apart trying to get to the leaking rear oil seal. I'm no experienced mechanic, just trying to learn as I go along, so I've got two rookie questions:

1. The 2GM20 shop manual (p 125) instructs me to "apply gasket sealant to the periphery of the seal". I have some Permatex Aviation #3 on board, would this be suitable, or are there any better options out there? Ideally a non-adhesive one, so that the oil seal can be easily removed in the future.

2. Page 23 of the same shop manual instructs one to "Pack grease in the seal lips before the seal is installed.". Onboard I have Lewmar winch grease, and grease for the Volvo shaft seal. Would either of these be suitable? If not, do you have any idea what sort of grease I should use?

 

[garymalmgren]

1. The 2GM20 shop manual (p 125) instructs me to "apply gasket sealant to the periphery of the seal". I have some Permatex Aviation #3 on board, would this be suitable, or are there any better options out there? Ideally a non-adhesive one, so that the oil seal can be easily removed in the future.

Permatex will be fine

2. Page 23 of the same shop manual instructs one to "Pack grease in the seal lips before the seal is installed.". Onboard I have Lewmar winch grease, and grease for the Volvo shaft seal. Would either of these be suitable? If not, do you have any idea what sort of grease I should use?

Just to be safe , go out and get some standard wheel bearing grease. This will be temperature resistant.

good luck.
gary

 

[sailoppopotamus]

OK thanks, I'll give some lithium bearing grease a go. I don't really understand what the purpose of the grease is but I imagine that if the choice of grease was so crucial they'd be more specific about it.

 

[garymalmgren]

"Pack grease in the seal lips before the seal is installed.".

This is probably to make the fitting of the seal easier
and to ensure a proper seal on the crankshaft.

gary

 

[vyv_cox]

I find both instructions to be quite odd. I have fitted crankshaft seals to all sorts of engines and have never done either.

 

[sailoppopotamus]

I find both instructions to be quite odd. I have fitted crankshaft seals to all sorts of engines and have never done either.

It has taken so much effort to get to the rear seal (still not quite there) that I really want to make sure it won't leak after I put everything back together!

 

[WindyWindyWindy]

Don't you just take the gearbox and the flywheel off and pull it out?

 

[sailoppopotamus]

Yes, that's the idea, but reality turned out to be not as simple.

The damper plate bolts were solidly rusted on, so I had to buy a flywheel locker just to be able to apply sufficient torque on them. Then the damper plate itself, a seriously rusted piece of metal wouldn't come off. 'Luckily' two of the springs in the plate were loose and rattling, so I decided that the damper plate is done for anyway. Even after deciding on destructive removal it took more than an hour of strategically banging on the thing to break it off the flywheel.

Of course the flywheel seems to be similarly rusted on and refuses to budge after undoing the bolts. The manual suggests screwing on the damper plate bolts and pulling it from there -- I haven't tried this yet. If it doesn't work I'll have to make some sort of puller for it based on the same idea. So I'm almost there. Many suggest removing the bearing holder and pushing the seal out this way. I'll try this first, as an opportunity to replace the O ring that's there just in case that's leaking oil too. If I can't get the bearing holder off, which seems the most probable scenario, I'll just pry the seal out and hope the O rings are not responsible for the leak.

I have no idea why my engine is so rusted inside, I bought the boat last year and don't really know its history.

 

[Boater Sam]

Yes, that's the idea, but reality turned out to be not as simple.

The damper plate bolts were solidly rusted on, so I had to buy a flywheel locker just to be able to apply sufficient torque on them. Then the damper plate itself, a seriously rusted piece of metal wouldn't come off. 'Luckily' two of the springs in the plate were loose and rattling, so I decided that the damper plate is done for anyway. Even after deciding on destructive removal it took more than an hour of strategically banging on the thing to break it off the flywheel.

Of course the flywheel seems to be similarly rusted on and refuses to budge after undoing the bolts. The manual suggests screwing on the damper plate bolts and pulling it from there -- I haven't tried this yet. If it doesn't work I'll have to make some sort of puller for it based on the same idea. So I'm almost there. Many suggest removing the bearing holder and pushing the seal out this way. I'll try this first, as an opportunity to replace the O ring that's there just in case that's leaking oil too. If I can't get the bearing holder off, which seems the most probable scenario, I'll just pry the seal out and hope the O rings are not responsible for the leak.

I have no idea why my engine is so rusted inside, I bought the boat last year and don't really know its history.

Been a sinker?

Remove the starter so you can thump the flywheel from the front, working it round as you go?

 

[gordmac]

When I used to build the odd engine I used Hylomar on the outside of the seal and oiled the inside to aid assembly. For some modern seals one, the other or both are not recommended.

 

[sailoppopotamus]

Been a sinker?

Remove the starter so you can thump the flywheel from the front, working it round as you go?

Been a sinker?

Remove the starter so you can thump the flywheel from the front, working it round as you go?

Turns out a variation of the Yanmar tip is the trick to getting the flywheel off. I found some 20cm M8 studs which I screwed into the holes meant for the damper plate. These allowed me to wiggle it loose. No signs of any rust past the flywheel so it doesn't look like the boat had sunk in the past. I then undid the bolts for the bearing holder. The trick then is not to try to pull the bearing holder out, but to tap it gently (in my case I used a rubber mallet and a piece of wood) to get it to rotate a few degrees one way, then tap it to rotate it back to original place. Do this 2-3 times and it will too slide freely off the shaft.

 

[sailoppopotamus]

Interestingly, I'm now reading 2-48 of the massive 463 page 2GM20 manual and on the subject of oil seals, specifically the crankshaft oil seal, they say:

Spiral oil seals are employed at both ends of the crankshaft. This type of oil seal is pulled toward the oil pan by pump action while the engine is running so that there is no oil leakage.

Since the viscous pump action will be lost if the lip of the seal is coated with grease, coat the lip with oil when assembling.

So the instructions appear to be somewhat contradictory.

 

[Boater Sam]

Pre-oiling lip seals is the normal way, I suppose a thin smear of grease will do the same job , preventing the lip from friction burning on initial start up.

 

[gordmac]

Not having read the instructions specifically saying not to oil the seal on a VAG engine a friend was building he oiled it on assembly as normal, it leaked.

 

[Boater Sam]

Not having read the instructions specifically saying not to oil the seal on a VAG engine a friend was building he oiled it on assembly as normal, it leaked.

I cannot understand why pre-lubing an oil seal would make it leak. It has never happened to me and I have fitted many thousands.

 

[WindyWindyWindy]

It's worth checking the gearbox oil seals while you're at it.

 

[sailoppopotamus]

Thanks. The gearbox looks like a step up in complexity so I'll stay clear of that for the moment. Luckily there seems to be nothing wrong with it.

 

[gordmac]

I cannot understand why pre-lubing an oil seal would make it leak. It has never happened to me and I have fitted many thousands.

I would agree but VAG specifically say not to lubricate it. He did and it leaked, perhaps the two weren't connected but why say not to lubricate it?