Oil leak from exhaust manifold

[Shug1e]

Could someone help with a problem i`m stumped with on my GS1000EN. The bike runs fine and idles ok at 1200rpm but seems to be burning oil on only one cylinder (no4), smokes all the time. The exhaust is a Harris 4:! which is quite old and did not appear to seat into the cylinder head properly being restricted by the frame causing a slight gap in that cylinder (no4). It`s still compressing the gasket but still blowing wee drabs of oil especially under load. Could a lack of back pressure on that cylinder cause this problem?. I have ordered a new exhaust anyway. I stay up in a city called Dundee in NE Scotland and have a garage which faces out into a housing area mostly populated by OAP`s although its like being right in the centre of it!. Could any other GS owners imagine what it`s like, trying to fix ones smokin bike as every 30mins an old granny walking her 3 wee yorkshire terriers with tartan ties on their ears murmers " Ohh there`s that boy working on his motorbike again!" Any advice would be appreciated. cheers shugie.

[Dave8338]

Sounds like you got an enternal issue ie. rings or valve seal, causing the oil consumption. The fact that you can see it on the #4 header pipe, is a symptom and not the likely cause of the problem (though valves do strange things when subjected to too much cold air, too quickly).
Have you run a compression test on it yet? Does a plug read confirm the oil burn on #4?

[SqDancerLynn1]

I would check the cam cover first It could be leaking onto the exhaust. If it is comming thru the exhaust you probaply will need to rebuild the top end rings, valve seals maybe a rebore

[whiteboyslo]

tach cable seal leak?

Mike

[Shug1e]

Oil leak from exhaust manifold

Thanks guys, yes problem is internal, oil on plugs and compression is 10psi less on (no4) than the rest, will do another test tmro. I had a valve job done recently with new valve stem oil seals, is it possible one was inserted wrongly?. The bike sat unused since last september and the rings and barrels were bored less than 3 years ago. The thing i can`t understand is the bike runs fine apart from the smoke although stumbles occasionally at high revs which i think is the oil in barrel (no4). Do you think i should take the head off again or is it possible if it is a seal problem to fix with the cylinderhead in place? thanks for your help shuggie

[kurifu]

Did you do the compession test on a warm engine with the throttle open, or is 10psi a typo and you meant 100psi? Either way it is low, but 10psi is insanely low... low enough to make me ask if the piston has rings

10 psi no doubt means time for a rebore, actually I think 100psi is pointing you towards a rebore as well if you did your test properly.

[SqDancerLynn1]

it's possible that the valve seal was damaged during replacement ? One of the rings could have been damaged when it was rebored. Your best bet at this time is to get someone to do a leakdown test on the bad cylinder

[Steve]

Did you do the compession test on a warm engine with the throttle open, or is 10psi a typo and you meant 100psi?

No "typo" involved. Did you by chance do a "reado", reading his statement?

and compression is 10psi less on (no4) than the rest,

He never said what the compression numbers were, just that #4 is a tad lower.

Shugie, you say that the valves were just done. Is there a chance that one of the seals for #4 has come loose? Could be riding on the valve stem instead of attached to the head with the valve sliding trough it.

I don't know if it's possible with these engines, but I have changed valve seals and springs on cars without pulling the head. I adapted an old spark plug into an air fitting, brought that cylinder up to TDC, applied air (it holds the valves closed), then pulled the keepers, changed the springs and seals. Would still have to pull the cams on the bike, but not the head.


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[Shug1e]

Oil leak from exhaust manifold

Thanks guys, i did a compression test today and the readings were 135 130 130 120. Cylinder 4 being the problem area. With the exhaust off looking into the manifold area there is a lot of oil which i guess must be the valve stem seal in that cylinder. Would this problem cause the 10psi drop in pressure in that cylinder as frustrating as it is?.. guess i`m going to have to remove the cylinderhead again anyway.. thanks Shugie

[Dave8338]

Could be a worn valve guide or two...I'd have a look at the seats as well, that is, if you have to pull the head. Something is amiss, with all the oil.

I'd pull the valve cover first and have a look...you might get lucky and have a valve seal that climbed the stem, as Steve mentioned. The spark plug adapter/air fitting, works very well. Saves tons of time!

[Greg O.]

That much oil sounds like a valve seal. The cams and valves are flooded with oil to lub and help cool the upper end of the engine. I am wondering if maybe all the burned oil may have fouled a compression ring this would account for a lower compression reading. I have seen this on some cars from the dark ages..

Greg O

[Shug1e]

Oil leak from exhaust manifold

Thanks Dave, i dont have access to an air compressor, as good an idea as it sounds so am going to take the head off anyway. The machine shop i took it to in the first place missed a couple of worn valve guides i think. Is it possible to reuse the new cylinderhead gasket or will i have to get a new one? ... cheers shuggie ps are most of you guys from America?

[Dave8338]

I've heard it done...as far as the gasket is concerned, but I've always put on new ones. Once things have been compressed, they are less likely to seal again and you don't want to pull it apart for the third time, do you. :?

As far as where people are from, you'll find out quickly, that we're from all over the globe. Big Family of great people (if I do say so myself)