86 560SEL what happened?? :(
 

My 86 560SEL w/ 64K miles was running smooth as silk. Was sitting or a few days. Went out to drive it, started it up and it sounded terrible. Made loud knocking sounds but ran smooth, oil pressure gauge all the way up at 3 bars. I turned it off and now it won't even turn over!! Turn the key, everything lights up, turn key to start and just a hear a clunk. I've had a little trouble with the neutral safety switch, but could always jiggle the shifter and get it to start.

I'm worried the engine locked up from the terrible clunking sounds when I started it before.

Haven't gotten it to a mechanic yet. Obviously will need towed.

How could an engine that was so smooth and quiet just all of a sudden make such knocking sounds?

Could it be something simple or should prepare for the worst?

Sounds like the timing chain ate a plastic rail guide and then the chain jumped out of time and the valves hit the pistons. A standard way of failure for these engines. Expensive to fix at this point.

If that were the case, would it still run? The car started up fine and I let it run for a couple minutes. It didn't run rough, just made a loud knocking sound. Engine wasn't shaking or anything like that.

I think your going to find out that your 560 didn't have 64K on the clock. Have you tried turing the motor over by hand?

It checked out with autocheck.com when I bought it with 53K. Also, service stickers and books would support the mileage represented.

Did you inspect the engine for visible damage?

T- chain will sometimes knock a hole in the valve cover.

Perhaps an ancillary component failed- belt or pulley?

Nothing appears amiss.

here's an account of exactly what happened...

i got in the car, turned the key and started engine. shifted into reverse. HMMM... engine sounds different. shifted back into park. opened door. WTH?? sounds like a really bad valve tap but more clunky than that. opened the hood. car still running. everything looks ok. got back into the car. pressed gas to speed it up just a little, like maybe 2500rpm. still same sound. hmmmm... i better turn it off. turned engine off. tried to restart. turn key, just hear click. wiggle shifter cause i've had it not start a couple times cause it didn't seem to be in park correctly. just hear click. thought, oh f...

got into my trusty 85 300SD w/ 238K and went to office

560 sitting in the same place since then

From the limited description, IE not being present, it sounds like it jumped time.

The rails are plastic and should be replaced every 10 years regardless of mileage.

I'd remove the valve covers and take a look.

a mechanic friend who works on mercedes came by today. he wasn't able to turn the engine by grabbing the belts and turning. said that doesn't necessarily mean the engine is locked but he is usually able to turn an engine that way.

what's the chance if my timing chain has slipped that the engine ISN'T trashed??

rsmartin said: what's the chance if my timing chain has slipped that the engine ISN'T trashed??
_______________________________________________________________
Two chances...... slim and none. And Slim just left town.

You might get away with just doing the heads.

That was my first thought also, the plastic rail guide disintegrated or broke.

It ought not to have happened at just 64,000 miles, but then 21 years without having had it changed is a LOOOOOONG time on the original one.

Mileage and time causes the original ones which are white, to become root beer brown, and over time and mileage they develop hairline or big cracks, and eventually they let go. There is no set way to tell, on the 560, it varies engine to engine, but the best bet is to change them along with the chain and tensioner at 100,000 miles (typically driven in 10-12 years)

Yikes
My mechanic says wait for the rattle

Not feeling very comfortable here...

:eek:

If you "wait for the rattle" you are really taking a chance...many times "the rattle" is the first and last thing you will hear as the chain jumps time and the carnage begins inside the engine. 10 years and/or 100K miles...when you hit those numbers it is time for a new chain, tensioner, guides, etc.