Help with ticking engine - Boosted M42

[appletree]

Iv'e had this problem with this engine for a while and after loosing intrest in the car abit ive had a bit of a push to get it sorted again.

I first built this engine 2-3 years ago and it ran sweet as a nut when first built but then after running it in i started to get a slight ticking noise when the the car has been stood for a while and when the engine is still hot when it is re started.

The ticking noise is not there when the car is started from cold only when the engine is hot and the car has been stood for a short while, it is not that loud and doesn't change in pitch but will stay there for maybe the first 10-15 seconds of driving.

The noise is not there at idle only when under load.

If i leave the car to idle for maybe a minute or to when the oil is hot the noise wont then be there when i drive the car, but the other day i had to map the cold start and ran the car from cold till nearly normal operating temperature and i got the ticking again when i drove off but the oil was cold and the car had been stood for 5mins while i locked the garage and house.

I have fitted a completly different set of hydrolic tappets and the noise is still there and has not changed!!!!

The noise is also a off beat sort of noise like its only on one cylinder not all the tappets that are low.

Also if i rev the car to 3krpm a few times when the ticking is there it will normaly go away.

Could this be a stuck/sticking injector??? they have all been refurbished before they went in and i have done 6k miles on the engine now.

I'm alittle worried it could be piston to valve contact on one cylinder but then this would go againt all the symptoms as it should get worse as the tappets pump up but mine does the opposite.

My oil pressure is around 5Bar when cold and 1.3Bar when hot which seams to be what BMW recommend for the M42 and this has been the same since i built the engine, under normal running i get 3-4bar above 2krpm and its running on 5w40 oil fully synthetic and i have try'd 10w40 fully synthetic oil and the symtoms where the same.

If anyone could offer any advise or has had simular i woul be grateful of any help.

Thanks Matt

[Dave_M3]

I presume you sorted this by welding the exhaust manifold up?

[appletree]

I did ya although it was a mint uncracked onevwhen it went on, when it came off it was cracked on oneand four runners more than half the way round. Now iit's been welded inside and out with dissimilar rods.