Hello all,

Here's a mystery that I'd like to solve. Or if, it's normal for my old Benz, I'll deal with it.

About 80% of the time, my car idles very nicely. It starts a little rough, but after about 5 seconds it's surprisingly smooth.
20% of the time, however, I'll come to a stop and it will be a bit more 'rumbly' and have more shaking in the cabin. I haven't detected any pattern to when it happens, and it's not that bad, but noticeable.

I thought at first it was air in the fuel system, but I don't have any fuel leaks that I can see.

All engine bay fuel lines are new (except for the cloth-covered return lines)
Fuel filters are new
I did a recent diesel purge
Air filter is new

Any ideas?
82' 300D

Rough like vibration, or wobble?

My 82 300cd is wonderfully smooth, but when the engine is really hot and idling for a while, it starts to get a bit of a wobble.

Could be a bad line that lets a bit of air in... could be rack dampener spring gets soft when hot, could be that valves need to be adjusted again.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Rough like a wobble. The whole car feels like it's getting bumped around. Again, not very bad, but noticeable because it's normally very smooth - rivaling modern cars.

If you have never adjusted the valves might be a good place to at least check the clearances. Required maintenenace of these old cars every 15K anyways. Athough many have not been done for ages.

PO claimed the valves were adjusted last year, although at an unknown mileage. I'll be doing them again in a few months just to be sure.

Thanks for the suggestions all, I tightened up my damper bolt a bit and it smoothed the hot idle right out. Worked like a charm.
Thanks!