Going to grab some new filters this week.

Might be worthwhile to add that we took the car out today to see if we could get it to act up by driving hard on it, and it did not. Leads Ian to think that the car behaves until it's had some time to start getting warm under the hood, whereupon the lift pump (his favorite hypothesis right now) starts getting overworked and can't keep up. I can see the logic in that we can't get the car to consistently repeat the problem, in my eyes if the filters were the only issue it would be straightforward to aggravate the symptoms.

It would be worthwhile to check the crankcase ventilation. There have been instances of high crankcase pressure causing symptoms similar to yours. The pressure acts on the shut down valve in a manner similar to what vacuum does when the key is switched off.

Qwerty, the crankcase vent is intact. The factory air cleaner mounts and attachments have all be repaired. So, I don't think that's the issue; however, to be sure I will make sure the vent hose is unobstructed and securely fastened to the aircleaner and valve cover.

Thanks,

__________________
Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

It's been awhile. Been busy with life I guess. Glad to be helping Patrick (penalopizing1751) expand his horizons by buying a lovely MB diesel and showing him the tricks and trips.

Hope all is well with you,

__________________
Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

Figured I would post some closure since so many people gave their time to help me troubleshoot. Outcome has been forgiving and very simple. After changing both fuel filters (many weeks ago) and lots of highway driving, the problem has simply vanished. Very like that between the fuel filters being gummed up (and they were) and the car sitting for a long time before I bought it that it simply needed the pipes cleaned a little.

Thanks again everyone.

Glad to hear of a simple fix.

__________________
83 SD

84 CD

Really with any diesel a spare filter or filters should be kept in the trunk with the tools require to change them. This is usually much cheaper and faster than trying to source a filter at the time of need. Costs you no more really anyways as at some point the car is going to need a new fuel filter anyways.

Only buying diesel fuel at high volume locations is another rule that can pay off. Anytime they have bad fuel the truckers would be avoiding the place. They just have to take more care of their fuel they supply in general.