Hi guys, I picked up a 1982 300CD 270,000 miles non turbo last night. Perfect body, no rust, not repainted, super clean. Test drove it on two different occassions - started first piston up cold, no rough idle, no smoke, no cranking and warm idle above 2bar. When it was warm, there was no blue smoke, no black smoke, no white smoke. Engine sounded good with good power. Drove it home last night just fine. 1st thing this morning I jumped in it and it started up, gave it a few minutes to warm up and took off. about a mile from home going 25mph, it stopped dead. There was no loss of power, no smoke, no funny noise, nothing - just dead. When I try to crank it over, the starter sounds like it is bound up and the engine won't turn at all. It's not a dead battery, So my fear is that the timing chain snapped and Mr. Piston met Mr. Valve. I tow it home and remove the valve cover - The timing chain looks really good, it feels really tight, the timing chain tensioner is doing it's job and holding th timing chain in place. There are also no rods sticking through the block or pan. So what do you think? is it possible for the chain to be broken on the bottom end, but look good on the top? Can i remove the pan and check from the bottom? At this point I don't know what to do except remove the engine and start going through it. I'd rather know if you have any suggestions.


thanks
Jason

Ok, sounds like is not firm enough to base suggestions on...

Did you look at the crank pulley when the key was activating the starter ?

Did you try to turn it over at the pulley?

__________________
1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

my guess would be that it is in a bind. If you look at the crank pulley while trying to use the starter, it tries to move, maybe 1/32nd of an inch, but won't turn. I ran out of time and could not attempt to turn it over by hand. I am going to try that tonight. If the piston hits a valve, do these engines come to a dead stop? Is there an easy way to tell other than removing the head?

You have the valve cover off. Does it look like any valves are stuck in the open position? Is there a valve open with a gap between it and the cam?

__________________
1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

Bigbilly,

If the valves hit the pistons, the cam towers usually break but then the engine will turn. The cam can also break and the valves can bend.

Remove the GP to make sure the engine isn't hydrolocked. Its also possible the vacuum pump broke and some of the parts got into the timing chain.

Don't force the engine to turn or crank it with the starter. You might break something you don't want to break.


P E H

I can't imagine driving this car being as nice as you describe it and have it's engine suffer a major internal failure without a noise, a shudder or even a smell. You were going 25mph when it failed. This car's transmission has a rear pump and if nothing else, it would seem to me, that the inertia of the rolling car not being able to turn the engine, would have caused the rear wheels to skid. Did you notice any of that?


"If it was easy everybody would do it"!

Junqueyardjim

it make a crash sound when it stopped? that is what mine did when the vac pump failed. i was just taking off from a stop and crash. then nothing.... broken cam chain, broken cam, broken cam tower.

hope it s not that.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

That is the mystery. I would consider my self fairly experienced with MB diesels (this is my 3rd) I have replaced head gaskets, timed the IP pump, valve adjust, etc., so It's not like I don't have any experience. I have also been in a subaru and a toyota pickup when a timing belt/chain broke. That's what made this so weird. I am pretty well in tune to the noises the car makes as I drive it. But I did get some info from the guy I purchased it from last night - apparently he picked it up from somebody that had run it low on oil, however, I see no sign of scoring on the cam, nor did I hear any low end knocking that would indicate a rod bearing. (the dude is unwilling to refund my money and would rather work with me to see if the problem can be fixed).

So, the questions I have are:
1. Is it possible to break the timing chain without it appearing broken from the top?

2. If I remove the pan, can I see the bottom of the timing chain?

3. If the pan is off, how well can I see all 5 of the rods?

By the way, last night I tried turning the motor over by hand, and it was seized up tight. Wouldn't go forward or back. Also, I did not see any indication of stuck valves or valve tower damage. So I'm thinking bottom end - possibly rod.

So, if anyone has had the pan off, please let me know if it would be beneficial to pull the pan at this point.
thanks,
jason

When you were driving down the road... were you checking the oil pressure guage that morning ?

Bigbilly,

Running out of oil is bad news. A piston could be siezed in a cylinder. Usually a bad rod bearing won't stop the engine from running, but it will knock. Main bearings can sieze that might stop the engine from turning.

I figure an engine rebuild will be needed to correct the problem. If all the crankshaft journals aren't damaged, you might get away with just new rings and bearings. But when the head is off, you should do a valve job.

Removing the aluminum pan will expose the internals of the crankcase. You will be able to remove the bearings caps and determine if the crank is siezed or a piston is siezed.

P E H

although it's a longshot, a siezed torque converter could do something like you described. This could be checked by removing the bolts between the torque converter and flex plate, if you somehow got the engine to move (CW only, of course) the one rotation necessary to reach the bolts. Also, if the starter gear on the bendix siezed it might also do this. You can see the bottom of the timing chain and also the oil pump and chain by removing the steel oil pan. The upper (aluminum) pan is another story - that's best done with the engine out.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Thanks guys. Sounds like my weekend just filled up. Its supposed to be hot, so lying in the shade under a car may be just what I need.

Since it was a new (to me) vehicle, I was watching the gauges pretty well. Sounds like my only option is R&R of the engine. I'll let you guys know how it turns out.

thanks

A melted piston, caused by insufficient lubrication. I have seen a melted piston, looked kinda neat actually, all this molten metal from what used to be a piston.

If it is the engine, I have a 300SD engine (minus a few pieces - starter, fuel injectors, air pump, turbo,,,) but it does have the IP attached (so you don't have to time the IP) 230K miles only $500.

www.benzbonz.biz

Marty

Even if the oil squirter completely stopped working, at 25 mph the turbo is barely spooled up..and this was soon after starting the car in the morning... I doubt it had enough heat to melt a piston.
A systemic lubrication loss could cause this... but if it was being watched due to it being a new to him vehicle that seems strange also.....and even more so with the lack of any noises...
This is going to be interesting .