PeachParts Mercedes-Benz Forum - At the end of my patience-1984 300D issue

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Quote:

Originally Posted by ytr1903 (Post 3108933)

Hi all,

My son is still driving his 1984 300D, or at least he was until a week or so ago.
Here is the situation. He doesn't drive it that much, maybe twice a week and even then doesn't drive it very far. In any case, a couple of weeks ago he went to start it and the battery was dead. He took it to get checked and found that it was a goner. It was about 8 years old or so. He installed the new battery, the car started right up, but had no power. He can sit in the driver's seat in neutral and floor it, the engine will only rev to around 2200 rpm. He called me for some of my sage, fatherly advice, so the first thing I told him was to change the primary and secondary fuel filters. He did that, tested it and no difference. I told him to check the Alda connection for blockage, he did that, no difference. Alda line was open. I live about 50 miles from him, so it is difficult to get really involved with the problem, but yesterday we were near his house so I we stopped in. I had him start it, while I cracked each injector open. Each time the engine would falter, as if that particular injector was performing correctly. I then did a diesel purge, (thereby, eliminating the tank strainer, and cleaning up the system at the same time). No difference. It idles just fine, but when revved, it puts out way too much black smoke. I have run out of ideas. Help!!

Tom

Interesting.

You have eliminated possible:
# Fuel tank vent and strainer.
# Plugged air filter.
# The primary and secondary fuel filters replaced with NEW.
# Alda line and ports are clear.
# Engine running cracked each injector open = Each time the engine would falter, as if that particular injector was performing correctly.
# Diesel purge = running the engine (isolated) from the can, (thereby, eliminating the tank strainer, and cleaning up the system at the same time).

No difference.
It idles just fine, but when revved, it puts out way too much black smoke.

This statement makes me think it is over fueling.

My best guess:
* Blow by + partial plugged crankcase vent = trying to shutdown.
* Turbo (damage) oil seal failure.
* Stuck rings = compression loss.
* Timing skipped.
* Injection pump internal issue.

.

If a diesel has black smoke, there is not enough air for the amount of fuel it is getting. If it was getting too much fuel, it would still rev when not under load. You may remember seeing big road tractors with black exhaust when pulling hills. That was caused by putting more fuel than the engine actually needed for the amount of air they were getting but they still had good power for pulling. In your case, I would say you are not getting enough air for the amount of fuel. There is a restriction somewhere. The turbo will not be in the game at this time as the engine is not pulling like it is when on the road. The restriction could be either the air intake or the exhaust. Not blocked completely, just restricted. If the fuel was restricted, the exhaust wouldn't be black.

My $.01 worth.

Paul

That is an interesting thought Paul.
Perhaps you might take off the U tube in front of the turbo. Even though the turbo isn't boosting it spins freely at idle.

I have taken the entire air filter and turbo hose off. While the engine was running, I put the palm of my hand over the intake. It reminded my of one of those old cartoons where the character gets sucked into the abyss. I kinda doubt that there is an obstruction in the intake. What would be the test for checking the turbo action? I don't hear any whine from it when we are revving the engine, but there must be a more definitive test that I can do.

Tom

If this happened suddenly, was it just after a fill up?

I got some bad fuel a few years ago and it gave me fits for a month with poor power and black smoke. The only thing that finally helped was running a tank of B85 biodiesel through it on a good long trip. IIRC, it took 2 tankfulls to finally get things back to normal. Do you have access to biodiesel in your area? (less expensive a than significant volume of Diesel Purge)

When you did a diesel purge, it sounds like you disconnected the fuel lines and ran it directly from a container. Did you just run it at idle or did you do some revs? When your son changed the fuel filters, did there appear to be any kind of discoloration (primary) or was it crystal clear? Is there any indication of fuel leaks around the lift pump/primer pump?

Quote:

Originally Posted by barry12345 (Post 3108982)

Turbo frozen? Assuming the engine could not have jumped timing. The black smoke is indicative of little or inadaquate air. You seem to be getting lots of fuel.

Exactly what I was about to write.

Pull off the U-tube and see how easily the turbo spins when the engine is off. Then see how it spins when the engine is running. Don't put your fingers in there with the engine running.

Quote:

Originally Posted by kerry (Post 3109007)

Pull off the U-tube and see how easily the turbo spins when the engine is off. Then see how it spins when the engine is running. Don't put your fingers in there with the engine running.

Agreed.

Quote:

Originally Posted by ytr1903 (Post 3109001)

Should rev relatively normal with the u tube off under no load conditions if the turbo is involved I would think. Certainly there would be far less smoke. Thats if the turbo is involved in any way. Simple test but you also want to know that the turbo is turning as well.

Otherwise it could act as an exhaust restriction to some degree. Test it by hand prior to starting the engine to make certain it is pretty free or not. Plus the bearings are not really sloppy or disintegrated enough to hang up the impellors. I was also wondering if a wide open egr valve would do this as well. Not really sure though. Since I am not sure I would check it on my own car but other members with more experience may have differant opinions. Your effects are pretty bad currently whatever the cause is.

I have called my son. After work today, he will pull the U tube off the turbo and try to spin it with his fingers. (I emphasized that the engine has to be OFF). Thanks to everyone ,so far, for their interest and helpful suggestions on this problem and I will let the forum know what the outcome of the issue is, even if it is scrapping the car.

Tom

Does it rev from under the hood? On my dads 84 cd the firewall mounted bushing ripped an made it so the car would not rev past a certain point from the pedal. He was able to wrap his belt around it and make it the 400 miles home. Would not explain your soot issue tho.

I forgot this was a father and son semi remote deal. Tell him to only manually check the tubo when the engine is cold. They can get pretty hot.. I would not like to see any member or their son sustain any form of injury.

Many do not even realise they can spin up to 150k and can take some time to unwind. It is wise to idle the engine to keep oil flowing through the turbo bearing when coming off the highway. Technically you can coke up a bearing otherwise. It also gives the engine a little additional time to equalise the internal operating temperatures. .

SOLVED!!!

Barry12345 wins the prize. My son got home from work, stuck his fingers in the turbo and pulled the inner ring to the U tube out. The car runs just as well as it ever did now. I want to thank EVERYONE that helped out here and hope that the thread will help someone else in the future.

Tom

Quote:

Originally Posted by ytr1903 (Post 3108956)

Jim,

The exhaust has to be open, the engine is throwing massive amounts of smoke out of the tailpipe as it is revved.

Tom

Not necessarily, my 87 300TD had massive amounts of black smoke when the oxidation catylist plugged up. I dropped the exhaust just behind the turbo, and found the lost power. I subsequently broke out and removed the matrix from the OC, just leaving the hollow shell.

Jim