Oil Leak from side plate breather

[sirrom]

My 948cc engine has just started to leak oil from the breather pipe that originates from the side plate.
Have cleaned the rocker cover oil cap and also have checked the hose pipe from rocker cover to carburetor body.
Also have done compression test and in cylinders in 150psi range.

Any ideas

[MarkyB]

Has the oil been over filled?

How much air and fumes come out of the filler if you take it off with the engine running?

[sirrom]

You can feel some pressure come out but not a lot and no fumes

[d_harris]

Simple enough job to replace the gasket if its leaking. 1x 1/2" bolt, scrape the old gasket off, replace gasket and rubber o-ring and refit. 5 minute job. Did it this afternoon on Agatha.

BTW, get the neoprene gaskets (the cork ones I got today weren't a great fit..)

[sirrom]

No its not the side plate gasket - its coming out at the bottom of the breather pipe, thats the breather pipe that comes from the front side plate and goes down beside engine.
Just been for a short drive to double check whether fumes from oil filter cap but really none.
If you leave car idling you can see oil dripping out the bottom of the breather pipe and its a drip every 10 seconds.

[MarkyB]

That's way too much.
Put your least favourite clothes, and you dirtiest overalls on, and try running the engine with that cover and the rocker cover off.
It may be obvious as soon as you take the push rod cover off.

Be prepared to replace both gaskets as Dan says.

[bmcecosse]

Does sound like pressure in the crankcase - it's MUCH better if you can connect the rocker cover breather directly to the carb (or even the inlet manifold) to suck the fumes away. The later carbs have a connection on the side to facilitate this.

[sirrom]

Sometime ago after reading all the posts about crankcase pressure I had another carby so I changed the base that the cooper filter housing sits on and connected the rocker cover hose to that.

Could I fit a 1098 side cover as they have the pipe going up and over down to the pipe.

[mike.perry]

Sounds like a good suggestion or the later 1098 side plate with the canister attached.
Is there a baffle over the pipe hole on the inside?

[bmcecosse]

Either option would probably help - but must be used with the later 'rubber' gaskets.

[mike.perry]

Just remembered a small difference between the 948 and 1098 tappet chest covers, one slopes in to the centre, the other slopes out, I can't remember which. You may have to change the centre stud or increase the thread length.

[MarkyB]

The picture in this thread shows it;
http://www.mmoc.org.uk/viewtopic.php?f=8&t=35689#unread

The reason the pipe design was changed is probably a tendency for oil to come out.

[sirrom]

Yes Mike there is a baffle on the inside of the 948cc plate with a small drain hole to return oil back to the engine. I tried making this hole a little bigger but still doesnt solve problem. Yes the 948 is convex and the 1098 concave so 1098 will need shorter bolts.

MarkyB thanks for the link.

[C6Dave]

Sorry to resurrect this thread but my 1098 sprung a small leak which appeared to be the rear bolt (below the manifold and in line with the exhaust clamp)

Took it out and sure enough the rubber seal had disintegrated.

I have done a temporary fix with a tap washer and have hopefully ordered the correct new ones from ESM as I only have a parts diagram for the 803 and 948 engines which have a different cover.

Anyone know where I can get an exploded diagram of the 1098 engine showing the side plates and bolts please to make sure I do fit the correct ones?

[bmcecosse]

http://www.moss-europe.co.uk/Shop/ViewP ... dexID=3525

[C6Dave]

Thanks, just what I needed.

I have already bought 2 cup washers and seals from ESM (guessed as no diagram) but, I think the actual gaskets may be leaking.

I have everything cleaned down and am waiting to see where it comes from now (new cup washer and seal seems to have fixed the bolt leak) but the leak is now minimal.