When I got off the freeway near home today, the idle in the 83 SD was way out of whack. It felt like it was going to die. It was fine when running but there are several lights and stops along the way. It was an agonizing 3 miles to the house speculating what could be so wrong and hoping it wouldn't get worse 'til I got home. I popped the hood in the driveway and did a visual inspection with the engine running or rather bobbing. Everything looked as it should; belts and pulleys weren't wobbling, no leaks from the injectors or high pressure lines, dry return lines, all vacuum hoses in place, clear flow through the prefilter... what's that? The primer pump handle (screw-in type) was jumping up and down on its own! I screwed it back in and the idle settled. I'm not sure if it's back to where it was but it didn't feel like it was going to die.

Quite a scare.

Sixto
91 300SE
87 300SDL
83 300SD ... any takers at $1100?

I've had this happen before but it had no effect on how the engine ran, it only leaked fuel and smelled.

If it happens again I would just put on a new one, they are inexpensive and quick and easy to replace.

Good luck,

Sixto,
Same thing happened to me too except I first noticed a slight fuel leak. I have no idea how it got loose but it did. Now every once in a while I check it to make sure it is snug. No harm done in any case.

__________________
LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Get rid of the old style pump next chance. The BOSCH redesign with the black push button is great. I found Performance Products was still selling the old white screw down pump which was a piece of junk while many suppliers had stopped carrying it. It has a tendency to leak diesel fuel past the o-seal under the pump handle even when screwed down tight. I also found the redesigned pump is cheaper/easier to install. Good Luck.