240D death sentence? - PeachParts Mercedes-Benz Forum

Joe Bauers · #1 09-23-2007, 06:20 PM

There's a young man who lives a block away from me who owns a 1980 240D, which he's been running on veggie waste oil. Car was running fine, but then suddenly one day it would not start. Turned over, but would not start.

Since the starter was balky, he took it out and had it replaced with a rebuilt, which turns nicely; he also replaced the battery. After removing the valve cover to check valve clearances, we discovered that the starter engaged, but the valve train would not move.

Could it be a broken timing chain? I thought this unlikely, given the double row chain. My knowledge of MB diesels involves all maintenance procedures, but I have never delved into the inner workings of the engines.

Any input would be appreciated.

Joe B.

kerry · #2 09-23-2007, 06:28 PM

Got to be something like a broken chain. Could be a sheared off key somewhere.

pawoSD · #3 09-23-2007, 06:38 PM

Does the crankshaft spin? If not maybe there's a dead spot on the flywheel teeth (broken tooth?) otherwise it'd have to be the chain, or the starter is indeed not engaging the flywheel at all....would be a bad starter bendix.

You can verify engine-functionality by rotating it clockwise with a 22mm wrench on the P/S pump nut.....if everything moves its probably fine.

Also, if it were a bad chain, and the starter were spinning the rest of the engine, it'd not sound good, because you'd be hitting valves as the pistons came up....which is why I bet the problem is the starter, not the engine.

Joe Bauers · #4 09-23-2007, 06:43 PM

Actually, I tried to move the engine by hand on the Power Steering pully--will not turn the engine that way. Seems locked.

Thanks all for input.

Joe B.

Dewhite2485 · #5 09-23-2007, 08:49 PM

if it is trashed and he wants to sell let me know Im located in Taylorvill Il.

Stevo · #6 09-23-2007, 08:52 PM

First I would put a socket and breaker bar on the crank nut and make sure the engine wont turn over. sorry I forgot what size

Make sure one of the belt driven things are not holdings things up.

TheDon · #7 09-23-2007, 08:55 PM

Quote:

Originally Posted by Joe Bauers

Actually, I tried to move the engine by hand on the Power Steering pully--will not turn the engine that way. Seems locked.

Thanks all for input.

Joe B.

do it by the crank bolt

JimSmith · #8 09-23-2007, 08:58 PM

Joe,

On my 1982 240D I had a problem once when it wouldn't start for a variety of reasons. I even tried to start it by pushing it with another car, and the engine just locked up. Turned out the fuel injectors had put enough fuel in the combustion chambers that one of them was hydraulically locked. Pulling the glow plugs released the engine.

So, if the unit has been spun for long enough to cause a cylinder to fill up enough to lock the engine, try pulling the glow plugs. In any case, try the starter with someone looking at the front of the engine to see if the pulley are turning. Seems like it is going to be associated with the new starter - one of those old lessons, if you do something to the machine and it stops working, there is a good chance the thing you worked on is the problem.

Good luck and keep us informed. Jim

pawoSD · #9 09-23-2007, 09:43 PM

Shouldn't the fuel be blasted out the exhaust valve if its being spun without starting? Seems like it wouldn't just pool in there.....I know in the winter if you crank a long time the exhaust smells like unburned diesel....

JimSmith · #10 09-23-2007, 09:55 PM

If the fuel is atomized by the injector it will generally blow most of the fuel out, or at least all that is still atomized. If the engine is turning over slowly, and the injectors are not being overwhelmed by the injection pump pressure build up, you get a combination of bad atomization (more of the injected volume is liquid, less is atomized) and low ejection of the liquid fuel out the exhaust valve. This continues until the starter can't turn the engine over. The unusual part of this case is the starter seems to be operating ok, and the engine can't be turned over by hand.

Jim

JimSmith · #11 09-23-2007, 10:57 PM

I just reread the original complaint and apparently the car has been running on vegetable oil, and vegetable oil that might not have been heated. It is more likely this stuff has filled the combustion chambers as at lower temperatures it doesn't flow as well as the formula for Diesel #2 you get from the pump. Jim

pawoSD · #12 09-23-2007, 10:58 PM

Looks like you should pull the glowplugs and crank it over a bit.

lietuviai · #13 09-23-2007, 11:35 PM

Quote:

Originally Posted by Stevo

First I would put a socket and breaker bar on the crank nut and make sure the engine wont turn over. sorry I forgot what size

Make sure one of the belt driven things are not holdings things up.

IIRC it's a 27 mm socket.

Joe Bauers · #14 09-23-2007, 11:44 PM

All input appreciated. Tomorrow, I'll advise the young man to pull the glow plugs and see if that relieves pressure and allows the cam shaft to turn.

I will keep you posted.

Joe B.

JimmyL · #15 09-24-2007, 01:38 AM

Something else to consider, or at least verify. If the 240D has a manual tranny make sure it is not in gear when trying to turn the engine by hand. This bit me once, so I just thought I would mention it......