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Friday, 20 June 2014

Moto Guzzi Cafe Racer Cylinder Head oil leak.

After chasing the higher than average oil consumption on my Cafe Racer - I'd originally thought it was rings / bores due to the apparent occasional puff of smoke on acceleration - I found, under further investigation that the inlet valve on the l/hand side overly soaked in oil. I went through my spares and found another l/h head with very good valve / guide fitment. So that should sort it............or so I thought ?
  I opened up the inlet to take the bigger Leman 36mm carb manifolds.
  Got it all back together and got out later that evening for a test ride. Twenty miles outside of Bristol,after my foot slipped while changing down a gear,I found that I had a oil leak. Got back home and found the cyl head oil feed pipe seemed to be leaking (not that uncommon) with a small puddle on top of the crankcase. Fitted another and the next day got out again. Twenty miles and all fine,so I'll go a little further. Another 15 miles and my foot slipped again with the same quantity of oil over my trouser leg etc,but no leak from the oil feed pipe this time.
   To cut a long story short and after another couple of trips out, after re-routing breather pipes etc and still not being able to figure out where the leak was coming from I decided the the head had to come off again as maybe the head gasket was somehow leaking without actually blowing..........??
   I took the cyl / head over to my friend Martin, who cast an eye over it with his specific inspection light / magnifying glass which can get into nooks and cranny's and  he spotted a hole in the casting between a couple of fins and a tiny pin prick of a hole which corresponded perfectly within the 'inlet' pushrod tunnel.
   It all makes sense, as the hotter the engine gets the more the hole would expand and the faster I went the more oil would get circulated.
  The head is back at the welders where hopefully he can get his torch close enough to weld the spot. 
  In all of my 22+ years of Guzzi ownership I had heard stories of oil leaks from porous cyl / heads etc,but had until now, never come across any.
   Oh well,it's all a learning curve and I just want to get any issues sorted before selling it !
There was a broken off r/box bolt in the top r/hand fixing.
I got the bolt out and then welded.  I tidied it up,drilled and helicoiled it

I opened the inlet up for the 36mm carb manifolds

I don't believe it !
The cause of my oil leak and I guess quite a decent sized hole,
at least on the outside

The corresponding tiny hole on the inside

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