2BRacing
Forum Mentor
Just thought I would like to share my experiences in trying to solve a mystery oil leak. Similar to Mr Rusty's post recently on oil apparently dripping from the short head bolt in front of the timing chain housing on his GS1100E, I had the same on my GS850. The first "diagnosis" that came to mind was "leaking head gasket" in that area. However, another clue was oil on top of motor in area of oil pressure switch / cam chain tensioner.
After searching other threads here, I "decided" the culprit was leaking cam chain tensioner, as someone at my local dealer confirmed that oil could run through fins above tensioner towards front of motor, thus running down to "lowest point" - the small bolt in front. Following excellent photo guide (courtesy Mr BWRinger) I duly replaced O-rings, seal and gasket on chain tensioner and replaced assembly. Washed motor down with cleaner. Went for a 50 mile run, and what do I find? Still oil dripping from short bolt!
However, now that everything was clean, I could see that oil had run from around spark plug number 4, along fins and down to short bolt in front. OK, new "diagnosis" - leaking cam cover gasket - surely correct this time around, as oil must be coming from leaking gasket and run down between fins around spark plug, right?
Wrong again! - while removing bolts of cam cover to replace "leaking cam cover gasket", I noticed all were dry, except the bolt next to cam chain housing above number 3 intake, which was very wet with oil from top (head) all the way down to bottom of threads. Now that fuel tank was off, I could see oil puddle on top rear fin of head, and could see where oil had run down into area around spark plug number 3, from where it had run through fins to spark plug number 4, and along fins and down to short bolt at front!
I realised that the oil leak was from the threads of the cam cover bolt above number 3 intake, as the tapped holes in the head go all the way through at this end, and the area around the tapped hole in the head was wet with oil (could not see when fuel tank was on). Still busy cleaning everything up before replacing cam cover (and also going to measure / adjust valve clearances while everything off anyway), but this time I'm sure I've found the real culprit!
Moral of the story is probably not to jump to conclusions before thorough investigation!
Now I'm just curious as to why oil should leak down the threads of just this specific bolt? Any suggestions?
After searching other threads here, I "decided" the culprit was leaking cam chain tensioner, as someone at my local dealer confirmed that oil could run through fins above tensioner towards front of motor, thus running down to "lowest point" - the small bolt in front. Following excellent photo guide (courtesy Mr BWRinger) I duly replaced O-rings, seal and gasket on chain tensioner and replaced assembly. Washed motor down with cleaner. Went for a 50 mile run, and what do I find? Still oil dripping from short bolt!
However, now that everything was clean, I could see that oil had run from around spark plug number 4, along fins and down to short bolt in front. OK, new "diagnosis" - leaking cam cover gasket - surely correct this time around, as oil must be coming from leaking gasket and run down between fins around spark plug, right?
Wrong again! - while removing bolts of cam cover to replace "leaking cam cover gasket", I noticed all were dry, except the bolt next to cam chain housing above number 3 intake, which was very wet with oil from top (head) all the way down to bottom of threads. Now that fuel tank was off, I could see oil puddle on top rear fin of head, and could see where oil had run down into area around spark plug number 3, from where it had run through fins to spark plug number 4, and along fins and down to short bolt at front!
I realised that the oil leak was from the threads of the cam cover bolt above number 3 intake, as the tapped holes in the head go all the way through at this end, and the area around the tapped hole in the head was wet with oil (could not see when fuel tank was on). Still busy cleaning everything up before replacing cam cover (and also going to measure / adjust valve clearances while everything off anyway), but this time I'm sure I've found the real culprit!
Moral of the story is probably not to jump to conclusions before thorough investigation!
Now I'm just curious as to why oil should leak down the threads of just this specific bolt? Any suggestions?
