Hi Folks,

I need some assistance diagnosing the noise coming from the top of my engine. I think it is chattering valves and need a valve job...

The brick in question is a 1991 245 B230F M47 with about 197k miles. I have been running a high lift profile came from Unitek in the engine for about 80k miles (stock springs, advanced 6 degrees). I have revved the motor pretty hard at times and probably put wear on the head that way.

The noise:
A distinct valve clatter at different RPM and load settings. Not very loud at idle. Louder under acceleration. Pronounced when the throttle is lifted after gradual acceleration or say if I accelerate from 60 mph up to 70 mph on the highway. That is, at higher revs and under load the knocking is louder. Clatter is there with engine hot or cold.

The valves were super loud and clanky but I put in new rubber valve cushions and adjusted the valve clearance with shims and it quieted down a lot. There is still clatter there though as described above.

I don't think it is piston slap but I'm no expert and don't know exactly what piston slap sounds like.

I do have a spare head which I am preparing to send to a machine shop for a valve job and then swap it in but I'd like to confirm what the valve clatter noise is before I go any further.

Thanks for any help.

Bert

Bert,


It is likely a worn camshaft.


Goatman

Interesting... What's the best method of confirming that?

The cam is aftermarket so getting the factory specs to measure against may be problematic. Guess I'll try contacting Unitek.

Thanks for the tip!

Bert

Bert,


Typically valvetrain noise that remains after adjustment is caused by a worn opening profile on the camshaft.

Volvo got into big trouble this way on the PRV motor. It's how I ended up with my 264.


Goatman

This makes sense for a few reasons.
First, it being an aftermarket camshaft it may not be made as high quality as a genuine Volvo part and more likely to wear.
Second, I inadvertently ran the cam for quite awhile with lax valve clearances. This may have sped up cam wear. ???

I did notice a distinct wear pattern on the cam lobes when I put in the new valve cushions.

Swapping in a new cam is a lot easier than swapping in a new head...

Thanks,
Bert