1984 930 Turbo

[Lexn]

I have asked this before, but not got any solution.
My engine in good shape after overhaul runs good oil pressure ok, but when staring cold engine outside temp 10 degree C, a knocking sound is heard, the sound idsappear after about 5 mins when the engine goes down on rpm from about 1200 to 800 and noe sound are heard afterward, this is only for 5 mins each time, not regulary, maybee one time every 6 cold starts.

I think I have checked every possibility, but not the cam chain tensioners, it could not be the connecting rods since nothing is heard when engine hot.
Is this matter so easy that it could be the cam chain tensioners?

What to do, should I take then engine out or wait for some more seriuos things to happen ?

Regards lexn

[IMR-Merlin]

Grab one of these and you will be able to isolate where this noise is coming from better.

Amazon.com: Lisle 52750 Stethoscope Kit: Automotive

[speednme1]

Originally Posted by Lexn

I have asked this before, but not got any solution.
My engine in good shape after overhaul runs good oil pressure ok, but when staring cold engine outside temp 10 degree C, a knocking sound is heard, the sound idsappear after about 5 mins when the engine goes down on rpm from about 1200 to 800 and noe sound are heard afterward, this is only for 5 mins each time, not regulary, maybee one time every 6 cold starts.

I think I have checked every possibility, but not the cam chain tensioners, it could not be the connecting rods since nothing is heard when engine hot.
Is this matter so easy that it could be the cam chain tensioners?

What to do, should I take then engine out or wait for some more seriuos things to happen ?

Regards lexn

Check for an exhaust leak(cracked headers, exhaust manifold..etc..etc)....strange but they can sometimes make a tapping sound

[T77911S]

check valve adjustment

[krasuskyp]

good tip Rey - mine does that on cold start and it subsides in a minute or so, and the sound could be deceiving

comes from a header flange that's not fully square, I've tried retorquing it but it's best it's going to get

I wouldn't think valves out of adjustment sound would dissipate with heat / time

best bet Lexn is to post a vid here - we've got surprisingly good ears! 8-)

[mark houghton]

"...but when staring cold engine outside temp 10 degree C, a knocking sound is heard",

It's all in the translation. "Knocking" to me means deep, low frequency internal engine knock (Rod bearings). Tapping is an entirely different thing. Valve lash, and/or exhaust leak....two strong possibilities depending on what Lexn is actually hearing.