Hi! I have a problem with my 1951 Comet. Oil is leaking out between the cylinder head and the cylinder body. My understanding is that there is not supposed to be any gasket there, so how to prevent oil dripping down when the engine gets hot. It appears in the front of the cylinder in the vicinity of a pin bolt? Any advice? BR Ragnar
E: Engine Comet oil leak
- Thread starter Ragnar
- Start date
Ragnar,
That joint between the cylinder and the head is a lapped fit, much like the fit between the valves and the seats. If done correctly it should be fine for quite a long time. If not, it will leak.
It is just as likely that you have lost the fit between the cylinder muff and the cylinder liner, which allows oil to slip up between the two and leak out of the head joint. The answer will also depend on the condition of the engine. A leak down test will tell you what parts are leaking on your top end.
David
That joint between the cylinder and the head is a lapped fit, much like the fit between the valves and the seats. If done correctly it should be fine for quite a long time. If not, it will leak.
It is just as likely that you have lost the fit between the cylinder muff and the cylinder liner, which allows oil to slip up between the two and leak out of the head joint. The answer will also depend on the condition of the engine. A leak down test will tell you what parts are leaking on your top end.
David
It's is also possible that oil can leak past the rear right hand cylinder bolt and rise up and leak from the head. The rear right hand bolt connects to the oil feed of the cylinder liner.
Before pulling everything apart double check all the oil connections as the airflow under the tank and around the cylinder head could make oil appear to come from the joint, but could come from somewhere else. I have had this happen to me and it turned out to be a leak on the oil return to the tank. Does oil leak when it is parked and ticking over or only when you have been on a run?..John
Before pulling everything apart double check all the oil connections as the airflow under the tank and around the cylinder head could make oil appear to come from the joint, but could come from somewhere else. I have had this happen to me and it turned out to be a leak on the oil return to the tank. Does oil leak when it is parked and ticking over or only when you have been on a run?..John
Generally it's the condition of the two head faces and attention to the tourque given to the head nuts I stick to 32ft lbs.
It sounds as if you need to get a copy of Richardson. Look on the help page of the Vincent spares company for other reading material and also lots available if you use the search box above.
It sounds as if you need to get a copy of Richardson. Look on the help page of the Vincent spares company for other reading material and also lots available if you use the search box above.
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Hi ! Thanks. The leak comes from the right hand cylinder bolt. It is not from the oil return line. The oil starts to leak after a 10 minute ride. Any advice how to fix the problem would be appreciated. BR Ragnar
Sorry to tell you this, but; remove cylinder stud, non-setting jointing compound-NOT Silastic- on top section of thread into crankcase, then replace stud and put everything together again. At very least this involves removing petrol tank, and lifting, or removing head bracket FT3/1 and the Upper Frame Member.
Hi ! Sorry for not understanding English that well. How about putting on the pin bolt an O-ring or such preventing oil raising up and leaking out?
Not possible because of the waisting of the bolt. You could do what I do and fit an o-ring twix the head and barrel, but that needs a spacer to fill up part of the counterbore in the head.