Hello folks here I am again.
My 86 300sdl

2 weeks ago, the hard line from the injector pump broke at the pump (#1 line). I took it to my mechanic and was replaced. 1 week later the #3 hard line broke, at the pump, had it replaced. Afet noticing diesel fuel leaking on top of the pump, we replaced all the O'rings in the pump.

Now the car runs horrible. At idle, it shakes, alot, and doesn't stop until you reach 2,000 rpm's then everything seems fine. Back again to idle it's real shakey and continues until you reach 2000rpm's. Funny, but it ran fine even when the IP was leaking.

Took it back to my mechanic, who disassembled and checked all the O'rings to see if something had fallen in during O'ring replacement. Nope, not that. Then he checked fuel delivery from the injector pump, and #4 was not delivering any fuel.

In all your opinions, hopefully someone will have the miracle answer. Does it sound like I need a new IP?

As always your feedback and help is grealty appreciated.

Where to start?

I experienced symptoms similar to yours about 4 months ago. Unfortunately, the rough idling for me was due to a faulty #6 fuel injector and a leaking head gasket near the #1 cylinder. Both replaced. Additionally, I had quite a bit of surging at idle. The vehicle would consistently surge between 500-800 rpms. This lead to the diagnosis of the faulty IP.

Questions:
1. Does the rough idle calm down as the engine temp rises?
2. Is the car "hammering" consistently?

Hi Chris,

Thanks. No surging at idle. When the car warme up, the idle is still bad. The whole car will shake ubtil yo reach 2000+rpm's. What do you mean by"hammering"? The car is fairly noisey until it warms up, but after that it seems ok.

I was thinking about a pressure problem. Blows #1hard line, then #3 hard line, then develops leaks on the IP, so O rings replaced. Pressure from IP seems not constant.

Hmmm. Have you had the injectors checked? By hammering I meant clacking that is much louder than normal. Hammering is a sign of a faulty injector. Does the vehicle smoke at startup? If so, what color is the smoke?

Have not had injectors checked, great idea. It does seem to "hammer" at startup, but goes away. Don't really notice any smoke at startup, maybe a little, and I'd call it black-ish.

goldenbear,

I recently replaced the delivery valve o rings on my 91 350SDL.

I swear there is increased clatter - 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.

Any ideas?

George

Hi George,

I've been away from the boards for awhile. Are you familiar with the problems that plague the OM603.97 engine in your vehicle?