I have the same tapping noise in my two 740s, a 91 with 105k and a 90 with

136k. The noise is "piston slap" caused by low friction piston design. As the engine warms, the pistons expand to fill the cylinder. My 91 started

getting noisy at about 70k, and I haven't had any problems. Just let the car warm up in cold weather. Hope this helps.

My B230F (740) has never had a valve adjustment. It's about to hit 300,000 miles. The car has always (up until very recently) been dealer serviced. I asked about it once (about 220,000 miles ago), and the service manager replied that he's never seen valves out of adjustment on these engines unless someone messed with them. I had the same tapping noise, that was worse when cold. He said it was piston slap, and not to worry. I took his advice, the noise has not really gotten any worse, and the car rolls on.

Would anyone out there differ with the advice I received?

Have the same problem on my 150k B200F, checked the valve clearance, all ok, did the little seals under the buckets, still the same.

I guess the soft tapping comes from the injectors opening.

Reg,

If you haven't had them adjusted yet, this would be a good time to do it.

I agree with Ed. 30k or whatever they suggest is pretty optimistic... I just did mine at 100k, but it didn't fix the noise. So I replaced all of the valve absorbers (underneath the valve buckets). That didn't fix the problem either, although the old ones were trashed. The good side of all of this work is that the car is really powerful... well, for a 240.

It appears that I have a noisy exhaust manifold, or gasket. I'll deal with that some other time.

I think that my dealer recomended valve adjustment every 30k miles. My own experience indicates that this may be overzealous, but I incline toward the casual. If your valves haven't been adjusted for a while, it might be a good idea.

I had the dealer do mine at 90k, and haven't heard much noise there for the last 100+k miles.