79 300D engine died - help diagnose - PeachParts Mercedes-Benz Forum

orthotomeo · #1 09-25-2007, 03:59 AM

I spent a good hour searching and couldn't find any enlightenment.

I'm getting tired of mercedes problems.

I just adjusted the valves and everything ran much more smoothly for the past two days. On the way home I was coasting at about 30 Km/h (15 mph) and I heard a rattle and the engine died.

When I try to turn the starter it turns but it doesn't even fire.
When I took off the oil cap and looked at the chain it looked alright (but I'd have to take off the cover to make sure). The shaft look fine too.

What could be the answer? I got it pulled slowly the last block home and it's in the driveway now. It's just a matter of figuring out the problem.

I just hope it's not a broken timing chain AGAIN.

Thanks in advance guys.

DieselAddict · #2 09-25-2007, 12:47 PM

I would pull the valve cover and inspect. If everything looks normal, try rotating the engine by hand (using the crank).

orthotomeo · #3 09-25-2007, 02:29 PM

that will be my next step.

I noted that I was low on fuel prior to this, but there was no light on and no sputtering prior to the stall. Also, when I tried the primer it seemed that fuel was getting pumped.

First things first I will pull the valve cover.

DieselAddict · #4 09-25-2007, 02:53 PM

I didn't even think of running out of fuel, but that certainly could be the reason, especially if your tank screen is clogged and fuel level in the tank is low. In my experience there's not much sputtering when the fuel runs out. You said you heard a rattle prior to the engine quitting. Did it sound like something broke? If not it's probably just the engine running out of fuel.

orthotomeo · #5 09-25-2007, 03:57 PM

I wasn't sure. It could simply have been the jolting of the engine dying (I was moving at the time), but I may be hoping against hope.

It certainly wasn't the sound of valves cracking against pistons, much softer tacking, not even like a rod ping. I thought maybe vacuum pump, but I don't think that would cause the engine to stall would it?

I think one of the steps will definitely be checking the screen. The car has been through lots of fuel in the past 6 months, but It was sitting in a field for a year prior to that.

DieselAddict · #6 09-25-2007, 04:40 PM

The only way the vacuum pump could stall the engine is if it spewed its ball bearings into the timing chain cavity. I doubt that's what happened. I would just put some fuel in the tank and try to start her up again. You said the engine turned over with the starter so I doubt the timing chain is busted.

orthotomeo · #7 10-01-2007, 09:50 PM

Well The second chain in a year. I'm guessing it may be salvageable as it was broken at idle. The cam shaft didn't brake I don't think.

Sadly this will mark the end of my foray into mercedes. I started as a veg-oil enthusiast, but developed an appreciation for the cars (The last one wasn't converted, and I planned on restoring it for a daily driver with the parts from the other).

Thanks for everyone's help, this is an awesome forum and a good group of people. My post count is a minute fraction of the amount of times I've been here reading the posts and searching for answers.

Farewell and thanks for all the fish.

pawoSD · #8 10-01-2007, 10:02 PM

I'm guessing both those cars had the original chain on them?

They probably had a lot of stretch and were in need of replacement....

orthotomeo · #9 10-01-2007, 10:22 PM

probably right... I have all the original documentation (if anyone is interested in it) and don't recall the records of it.

sigh.

kerry · #10 10-01-2007, 10:28 PM

Wha are the odds of one person having 2 chains break? Don't buy lottery tickets.

orthotomeo · #11 10-02-2007, 10:06 AM

And don't ask me for advice on buying a car... I'm actually kind of afraid to buy any replacement vehicle.

vstech · #12 10-02-2007, 10:32 AM

the problem is you have non turbo cars... get a nice one with low miles and a turbo. world of difference.

orthotomeo · #13 10-02-2007, 05:32 PM

As far as selling it for parts. If the cam shaft didn't break, how bad do you think the damage is to the valves etc.?

DieselAddict · #14 10-04-2007, 01:23 PM

Sorry to hear about your misfortune. I was thinking a broken chain wouldn't let the engine turn over, but apparently it's possible. Good thing you removed the valve cover first. I would suggest next time if you ever get an old MB diesel again, inspect the timing chain first before driving the car for a long time. There's a good chance your chains were stretched or the tensioner was visibly bad and an inspection would have caught the problem before it was too late.