diesel power loss - PeachParts Mercedes-Benz Forum

#1 01-07-2006, 01:36 PM

I have been perplexed on a problem with my diesel. If you start out with it ... it will take off powerfully. After a short way maybe 3 miles or less it will act like something is pinching off the fuel source or something. You can just watch the speedometer start falling down and the speed deminishing. Also, if you look in the rear view mirror much black smoke rolling behind you. It will then finally clear up in a mile or so, and the speed and power will come back again. It seems to start easier doing this if there is an incline coming up not necessarily a large hill or anything. I have changed filters etc., but to no avail. If it was a plug I would think it would do this more constantly. It is a mid 80's 240 D. If you have had any thing like this happen I would appreciate any help on this. Thanks

TheDon · #2 01-07-2006, 01:40 PM

you are getting black clouds which means un burn fuel .. have you removed the in tank strainer and cleaned it?

#3 01-07-2006, 01:44 PM

No, I haven't removed the strainer in the tank. I thought about doing that, but someone told me it's a rather large filter like, and not likely the problem. If it constatly ran choked etc. I thought it would more than likely be there.

Brian Carlton · #4 01-07-2006, 02:05 PM

This is a more complex problem than fuel filters or strainer.

It appears to be getting all the fuel it requires, however, my guess is that the fuel is not atomized properly and is not burning correctly in the cylinder.

A bad injector can cause such behavior, however, I would not expect it to cause a dramatic loss in power that you have experienced. Additionally, the behavior of starting without a problem and suffering the issue after a short drive is perplexing. If it was temperature related, the problem should most likely be much worse when the engine is cold.

t walgamuth · #5 01-07-2006, 02:59 PM

but it never hurts to change fuel and air filters and use some fungicide in the tank.

seems to me most likely air or fuel problems, hence filters.

tom w

Matt SD300 · #6 01-07-2006, 03:22 PM

The car does not have FUEL STARVATION PROBLEM...plenty of fuel... black smoke!!! Check the AIR FILTER it is probably clogged

If you don't have clogged AIR filter. I would start looking at injectors or injector timing. Black smoke means too much fuel & not enough air. Its that simple...nothing wrong your fuel filters

Brian Carlton · #7 01-07-2006, 04:49 PM

Quote:

Originally Posted by t walgamuth

but it never hurts to change fuel and air filters and use some fungicide in the tank.

seems to me most likely air or fuel problems, hence filters.

tom w

It's not fuel filters because the black smoke clearly indicates plenty of fuel.

It's not the air filter because the problem occurs at a certain time after startup, continues for a short period, and then abates. The air filter doesn't suddenly cause a restriction, then magically clean itself up, only to repeat the scenario on the next cold start.

#8 01-07-2006, 06:17 PM

I sure appreciate your input. I have went the same way you'all are diagonsising it. When it is going right it will pull hills in flying colors very, very little if any slow down with the cruise on, as well. I have been toying with the idea, that maybe it might be egr valve related. Once it gets thru it's spell...you can drive 100 mile + and never a slow down again. I can have traffic backed up when it happens there is soo much black smoke!! It's like a James Bond Machine.

t walgamuth · #9 01-07-2006, 06:38 PM

like it is jumping injection timing. but if it were, i dont see how it could jump back.

tom w

#10 01-07-2006, 08:34 PM

Quote:

Originally Posted by Rebe

I have been toying with the idea, that maybe it might be egr valve related. Once it gets thru it's spell...you can drive 100 mile + and never a slow down again.

That's a very interesting thought because the ERG doesn't open until the engine warms up (temperature control on the thermostat housing). Have you tried blocking the vacuum line to the EGR? If that solves the issue, its an easy fix.

Also, some 240Ds (like my 83) have a "throttle damper" in the air intake (just below the air filter) that is related to the EGR operation. Have you verified that damper is opening fully when the throttle is open? That would also cause an air restriction.

#11 01-07-2006, 10:25 PM

Someone mentioned about using a fungicide in the tank too. Can anyone tell me where you can get it, and a name or anything?

estod · #12 01-07-2006, 10:38 PM

Biobor -- any marine supply store (easy to do here in Fla)

t walgamuth · #13 01-07-2006, 10:40 PM

but you can also get it at tractor and truck supply places.

tom w

#14 01-07-2006, 10:40 PM

Do you know the procedure on how to use it? Is it very complicated, and can it plug up the entire tank system?

Brian Carlton · #15 01-07-2006, 11:00 PM

Quote:

Originally Posted by Rebe

I sure appreciate your input. I have went the same way you'all are diagonsising it. When it is going right it will pull hills in flying colors very, very little if any slow down with the cruise on, as well. I have been toying with the idea, that maybe it might be egr valve related. Once it gets thru it's spell...you can drive 100 mile + and never a slow down again. I can have traffic backed up when it happens there is soo much black smoke!! It's like a James Bond Machine.

A question:

What's the status of the EGR valve? Is it connected? Or not? You may be onto a possibility........but.......it's remote.