Hello MBWorld,


I am a Mercedes-Benz enthusiast helping out a friend with his 1987 300TD (possibly might buy it). Here is the story:

In the fall of 2011, this wagon developed a coolant leak out of the water pump. It was a small leak, not causing any cooling issues or overheating, but he decided to park the car and fix it later. He never got around to that.

After a year, I found the car sitting in the drive way and knocked on the door, starting this adventure. I convinced him to let me mess with it. (This was late summer of 2012) I put a battery and coolant in it and glowed the engine twice. I hit the starter and it started up. A couple injectors were stuck but it leveled itself out quickly.

We took it for a short drive and the car was developing ZERO power. When the car was in drive, the engine would not go above idle. In park or neutral, I would get the full rev range.

After some research, I looked at a air control valve that opens intake air to the injector pump (close to the ALDA which I also looking to) After cleaning this air valve, finding that it is now stuck open. I drove the car and it did even worst. It was surging and slowed to a crawl. After turning around down the road, it died never to run again.

We replaced both fuel filter from the beginning, we bypassed the fuel tank with the "Emergency Fuel Tank" from MercedesSource.com.

All six glow plugs are getting 12V during the start cycle.

All six injectors are getting fuel with the feed lines are opened.

The primer pump is pumping fuel from the source to the injector pump. I have even operated it by hand and got any air out of the system (pushing a bunch of fuel to the return)

There is nothing blocking the air filter, the car was kept in a residential area.

Fuel is fresh.

I am at a lost at what it could be. I am about to give in at let a Bosch Injection Service deal with it.

Can anyone help me? I am suspecting a over-fueling issue. I heard bump starting the car could possibly cure this.

The car has 245K miles on it, originally from Alabama, now lives in Wisconsin.

It was running fine when it was parked.

I'm sorry for the super long post, I'm just trying to get all the info out.

Thank you in advance.

 

After standing for 3 years an oil change is in order. How is the oil level ? Was it stored outside ? Blocked exhaust?

A diesel only needs fuel / air / compression with the correct timing.

Let us know how you go.

 

The oil level is fine. A change is due though.

The car has been kept outside like in the picture.

I do not know how to check the exhaust but I might try to see if there is a nest in the muffler. I wouldn't think that would cause a no start situation.

 

Big weather difference between Alabama and Wisconsin, just because the glow plugs are getting 12 v does not mean they are working. Chances are they are now all burnt out, with the warm Alabama weather they would only have been cycled rarely because of the warm weather. Remove them and check for continuity with an OHM meter. might work for you. Also if you have been cranking the engine a lot the injectors have been washing the rings and possibly the engine oil is now contaminated with fuel, give it a smell. Also if it is cold as it seems, plug the car in to prewarm it, will not hurt.
Good Luck, let us know the outcome.

 

I agree with critter. Cold weather and a well worn engine are a bad combination for a diesel that lights the charge off using heat from compression. Even if the glow plugs are working, cold weather is a challenge for an old diesel. There is really no chance that over fueling is keeping it from starting as diesels have no need for a correct mixture like gassers do. If you have an engine heater, plug it in and get the engine warm. You can also blow hot air into the intake while you try to start it, as low compression has a better chance of getting hot air hot enough to light diesel fuel. If it does not have an engine heater, get one as it will definitely be needed in Wisc.

 

Here is some more facts:

I first started messing with this car this past summer where it was fairly warm. (75 to 80). This is when the no start occur.
Remember, the car did start and ran (with no power) the first time I messed with it.

The car does have a block heater, I could try to use it.

We do plan on replacing the glow-plugs and the intake manifold gasket (since you have to remove it)

Does bump starting it sound like a likely plan? I heard this was a cure in the old w123 diesel.

 

Good idea .I can't see how bump starting can cause any damage done properly & may be a good way to diagnose the problem.

You never know it may be just what the old girl needs to properly lubricate the rings , clean up the valve faces creating more compression & move the fuel through the system making sure all is primed.

Once started keep her going till she warms up.

Keep us informed.