Thanks for the suggestions.
I don't think its a hydraulic issue, as the follower is clearly free of the camshaft when the valve should be in the closed position , as seen by the other exhaust valve. No discernible valve train noise difference from bank to bank, or cylinder to cylinder when the trusty screwdriver to ear is applied.
So that leaves us with possible a carbon build up on the stem , as I think it closes once the revs come up and the cylinder compression rises quicker than the leaking valve can relieve it. SO chemical cleaning may be an option.
What is the BG machine mentioned ? Is it something I can do at home, or can anyone suggest someone in central Scotland who is known and trusted? I'm a bit sceptical of these things normally, but I am prepared to try something.
I cannot see it being a bent valve, as that would require some contact or hydraulic issue, neither of which there is any evidence of.
|