Oil Leak - Pooling around rear of vertical cylinder

[Howley]

I'm losing a fair bit of oil. It seems to be pooling around the rear of the vertical cylinder, and also in the spark plug hole of the vertical cylinder.

- I did a valve adjustment about a year ago and didn't replace the gaskets. Is it possible that the oil is leaking from the vertical valve covers?
- There is oil around the camshaft cover too, but it doesn't seem like enough to be pooling, but it must be coming from there somewhere.
- There was evidence of oil dripping from the fins and landing on the back of the crankcase, then running down.
- My other options are the base gaskets and the original crankcase breather.

Does anyone have any ideas? I've tried sealing up the breather, and removing, cleaning and replacing the old camshaft cover gasket.

[He Man]

i had that on both cylinders just like you described. after i replaced the valve guides, it went away. most of it came from the exaust vale cover and left cam cover.

[Speeddog]

Which year and model of Monster do you have, and how many miles on it?

Oil pooling around the spark plug:
Likely the cam cover on that side.
Possible that it's the intake valve cover.
Could also be where the oil gallery is plugged with the screw, slightly above and rearward of the spark plug.

Oil dripping from the fins:
Could be from the above listed items, additionally the exhaust valve cover.

It could be a base gasket leak, but evidence of oil higher on the cylinder makes that less likely.

Crankcase breathers just seem to ooze a bit, forming a film of oil on the surrounding area.

Possible that it's the O-rings at the head-cylinder interface, but same deal as the base gasket, not so likely if there's oil higher on the cylinder.

Best approach is to clean and dry everything as best you can, and then ride and inspect frequently to see where the oil is coming from.
You can use spray-on foot powder to get a better idea of where it's coming from.

The stamped steel valve and cam cover gaskets are tolerant of re-use.
The fiber gaskets, not so much.

[Howley]

It's a 94 M900 with ?84000km on the clock.

Thanks for your help, I'll clean it up and start with replacing the camshaft cover gasket, it was in poor condition.

[Pedro]

Replace the valve cover gaskets - they're dirt cheap and useless when you re-use them

[bigiain]

Crankcase breathers just seem to ooze a bit, forming a film of oil on the surrounding area.

I had one split where the top spout bit is joined to the lower body bit - it was all still held roughly in place by the hose, but it was leaking enough oil to run across behind the vertical cylinder and leak down past the front sprocket and make puddles on the ground. (I've got a spare output shaft seal from a hasty assumption when that happened...)

big

[bigmic]

Hi Big..
I presume you had to replace the part.. seams a faulty design. exact same thing happened on my bike yesterday. the crankcase breather that screws into the top of the crankcase was split across from front to back. Oil everywhere. It has been leaking for months. I thought it was leaking where the hose connected. the area is a mess because of that. Did you go for the air filter that does away with the reservoir under the seat etc.?
cheers
mic

[yotogi]

I have a similar leak and think it is from the left cam cover gasket. Very slow leak.

[Porsche Monkey]

I have a leak exactly like what the op described but it really looks like a head gasket problem. Ive already replaced the valve cover gaskets.

[Speeddog]

I have a leak exactly like what the op described but it really looks like a head gasket problem. Ive already replaced the valve cover gaskets.

What year and model?

[Porsche Monkey]

What year and model?

Oh my bad, wasn't trying to threadjack. Its a 97 M900

[Howley]

Threadjack away! It all helps! I replaced all the gaskets except the head gasket and it still leaks, just not as bad. There's a little allen head bolt in the head that it looks like it's leaking from. Could it be that?

[ducpainter]

M900 has no head gasket.

There are a few o-rings in there that's all.

[Porsche Monkey]

Engine removal required?

[ducpainter]

Engine removal required?

Not on a monster.

I guess you have to rotate the motor on an SS