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1978 CB 750 F2 - Oil pouring from above head gasket
stoutgoose:
Many thanks for this. My 'original' Honda workshop manual and the Haynes manual both omit this information. I'm just amazed at the volume of oil that was discharged, although the location from where the oil is coming (upper fins between cylinders 1 and 2 and 3 and 4 suggest this is the issue). Pucks were replaced and sealed in with Honda Bond. Rocker gasket is good, and the cam tower studs were never removed. I want to make sure this is the only cause of the issue before the engine goes back in again.
Thanks all for your replies.
--- Quote from: K2-K6 on May 07, 2020, 10:00:39 AM ---Below is a copy from official workshop manual for your engine.
(Attachment Link)
Shows location of special capped nuts and sealing washers to prevent oil leaks.
For sealing they mean the copper type. If you're unfamiliar with copper annealing, just heat to red on a gas ring and quench in water to soften the material and they'll seal properly.
Hope it helps your rebuild.
--- End quote ---
royhall:
It would have been a good idea whilst the cam towers were removed to give the oilways a good clean (apologies if you did it). This is where the obstructions end up and loss of oil will destroy the tower first then the cam itself. It blocks just below the cam journal. For what it takes whilst the cam cover is off again I would take the cam out and do the clean and replace the oil feed o-rings to the towers. It becomes a huge job after the engine goes back in. (Like I said, apologies if you have done it already just stressing the point)
Trigger:
Oil leaks in this area are caused by:
1, rocker cover gasket on up side down.
2, the cam tower studs were not sealed.
3, the bolts in the cam towers are too long and cracked the bottom of the hole. Or the bottom of the holes were already cracked.
4, pucks not sealed.
5, seal no good on the barrel dowels.
6, dome nuts and new sealing washers not used.
7, wrong size 0'rings used on the barrel to head on, the two oil feeds.
8, head studs too tight and has cracked the oil ways in the head.
royhall:
Wow, head back off to check that lot.
PHILIP2908:
As BryanJ says, its very easy to get the rocker box cover gasket on upside down.
I did this and had oil dribbling out the front of the engine after a re-build but was able to change it with the engine still in the frame.
See You Tube at:
https://www.youtube.com/watch?v=2orch75W2uI
If that link doesn't work, search for CB750 VALVE COVER GASKET CHANGE
Might save you having to pull the motor out again.
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