I recently replaced the delivery valve o rings and washers on number 1 and 2 positions (cylinders) on my 91 350SDL. I had a small leak.

I swear there is increased clatter - more like what some describe as hammering - it also seems to smoke more (whitish/blue) and rougher idle. It runs absolutely superbly at speed and after a moment or two - still noisier at idle, I think.

I would immediately just think this is the death of another 603, but it runs great all the rest of the time - 122K on it. And, it has always been rough just after startup.

Any ideas?

George