I'm Getting Frustrated - Still runs like Crap!
 

I don't know what is going on with my 87 300D. The symptoms are as follows: Lot's of white smoke, even when warm, which reeks of unburned diesel, engine feels like a gasser with a bad miss, seems to not have as much power as it should, and doesn't get great mileage. It starts right up every time though. I took it to a shop, and they told me they thought it was a bad injector, so I pulled them all and took them to get pop tested. The guy said all were fine but one, and that one cleared up when he increased the pressure to it. There was a buildup of hard black carbon on the end of the injectors, so I cleaned that off and put them back in. No change. So then I figured I'd better check the timing chain, which I had replaced about 6 months ago. It was right on. Checked the injection timing, the mark was right on at 14 degrees ATDC. So at this point I pulled the injectors again, and sprayed some PB Blaster in the prechamber then filled each one with Seafoam. I also had to clean off even more carbon from the injector, although this time it was much softer and easier to remove. Put everything back, and again no real change. So now I am a little annoyed, and buy a big container of Marvel Mystery Oil and hook up the fuel lines so it runs straight on the stuff. Didn't see a whole lot of black smoke, but it did run pretty smooth while on the MMO. But now it's back on diesel, and back to running like crap with lots of smelly smoke. What else should I be looking at here??

Which method are you testing the injection timing? The drip method should be 26 BTDC

By looking at the notch in the hole in the side of the IP.

There is no drip method for an OM603. And the spec for the 617 is 24BTDC.........not 26.

I think it's time for a compression check.

Smoke
 

Are you sure the turbo is working? Sounds like not enough air .....

I'm not positive it's working, what's the easiest way to check it?

The more I think about it, I don't think it could be a compression or turbo issue, because it runs fine on vegetable oil. In fact, I can tell when switching over to veggie when all the diesel is out of the IP by the way the engine quiets up and stops smoking and stops the nailing/missing noise which it makes on diesel. So I am almost positive this is a fuel issue, but if it's not the injectors or the timing, I don't know what else it could be. I can't imagine the IP is going out if it runs good on veggie, I would think that because it is thicker that vegetable oil would make any IP weakness even worse. Although the vegetable oil is being pumped into the IP at a much greater pressure than the diesel, but still that doesn't seem like it would affect anything. So I guess the key to my problem is figuring out what mechanical issue would be more evident when running the vehicle on diesel fuel.

I've read that the signs of a failing I.P. are often masked by the thicker veg. oil making up for the loss of tight tolerances.

Could It Be A Bad Load Of Diesel Fuel?

No bad fuel, it's been doing this for 5 months.

If it is the IP going bad, how hard are they to replace? Also, will one out of a 91 350SDL work in an 87 300D? They look the same, but the part number is slightly different.

how old is the timing chain?

It's new, I replaced it about 6 months ago. The problems seemed to start about a month after putting the new chain in.

Check your fuel return for the diesel side of your fuel switching. It sounds as if there may be a blockage that is causing pressure build-up.

How did you clean them? and did you clean them AFTER they got pop tested?
it's possible you scraped the injector and damaged the pintle.
this would cause poor fuel pattern yes?
rich mixture sounds like timing/ IP flow issues.
I think it's time to take the car to an indy to check the flow of the IP and the timing of it as well.
John

No, there is no blockage, and the return isn't looped so pressure build up shouldn't be the problem.

I cleaned off the burnt carbon with a small flathead screwdriver, but I made sure to not disturb the pintle. I suppose I may have to get them all tested again anyway, because I am not sure I trust the first test I had done on them.

I thought to check the IP timing you just looked for the notch in the "observation hole" on the side of the IP? That's what I did and it was at 14 degrees ATDC which is what others on this forum had said it should be. By IP flow, what are you referring to? Is there a way that I can check that myself? I am very hesitant to take this car to any shop, at least any around here. There is one guy that I know of that has worked on MB's for many years, but advice he has given me in the past has been wrong, and the people that work for him do shoddy work, plus he's not cheap.

Cheap things first. Check the compression as Brian mentioned. If okay I would weigh the cost of a good pump shop checking the injection pump out. It does seem somewhat logical to me that vegatable oil could mask a marginal pump in several ways.
Of course the pump may still be good yet you would want to know it for sure.
There is basically only testing it or replacing it unfortunatly.

0 to 60 time should be 14 seconds give or take an hour :P . that is probibally the best way to see if the turbo is working. it is possible for one of your cylinders to have bad compression. or you could just have a bad injector. And now that i think about it you could take off one injector line and run that injector off that line straight from the pump. you should get a pop and the fuel should atomize if it doesnt pop and it just kind of weeps out all of the time you found the problem.

Actually, that's a great idea to take out the injector and see if it's spraying. Will the car start up with an injector out? Will that hurt anything if it does? Maybe when they pop tested them they were putting more pressure to them than my pump does.

Oh, and my car can't make it to 60 in 14 seconds. Once I get the rpm's up it is pretty fast, but getting to those higher rpm's takes a long time. I took the ALDA off which seemed to help a little, but not significantly.

From your reply, I'm not sure you understood what I was trying to point out.

The fuel needs a return to the tank. If you are using a tank selector valve that does not provide for this, or if the valve is not working properly, then there is a problem of back pressure and air getting trapped in the fuel system.

0-60 in 14seconds?!! That'd be a slug for an '87. New with the trap-ox installed it was 0-55 in 8.7seconds and it's right in the sweet-spot for boost, can't take another 5.3 to make another 5mph.

Was the basic engine timing checked?when you replaced the timing chain.:)

so much so say lol. first of all it wouldnt hurt anything you would simply get air gushing out of the injector port maybie throwing carbon out. neat to watch if you shine a light in there. Now for your alda tisk tisk . i would recomend putting your alda back on and calibrating it correctly. if done right it will stop overfueling from happening too soon and it will help speed up your 0-60 time. this whole alda removal fad is annoying -_-

Now for your injector do as i said in my last reply and you should see it squirt fuel. if it doesnt squirt fuel or it just weeps out then you have a problem if it weeps then they pop tested it wrong and put too thick of a shim under the spring. if they didnt put a thick enough shim under the spring then you will get weepage. The pop pressure should be 115 bar and to get a good idle you have to get the pressure within 5 bars of the other injectors.

Did you use the RIV light to check the timing? Thats the only way to time a 603 series engine. You can get it close but looking for the notch in the port, but only close.

Your timing could be off a bit, 603's are not tolarent of the timing being off. Factory spect is 15ATDC +/-1 degree. 14ATDC is just about perfect actualy.


If you already tested it with the RIV light, then you can rule out timing. I'd do a compression test first, since its cheaper. Then pull the IP and have it bench tested. See what a Bosch shop says about the IP.

After hearing about the fuel thing I'm leaning towards the IP or timing.

I'm not an indirect-injection expert, but ANY mechanical cleaning of an injector in a DI diesel engine will damage the injector's spray pattern and cause the engine to run like crap. Do you have a spare set of nozzles you can swap to verify that's not the problem? I've seen VW TDI's where a "mechanic" cleaned the injectors with a wire brush and it caused the same symptoms you describe. I would never clean a diesel injector with any method other than injector cleaner (such as LM Diesel Purge).

Did you check the fuel filters?

I hate to be a wet blanket here with bad news, but did you check for a blown head gasket? This car has an aluminum head right?:eek:

Was it the IP or injectors????