qcar

My 500E was running beautifully, but then yesterday, all of a sudden during a hard turn and on heavy acceleration, all of the lights on the dash light up like a Christmas tree and the engine shut down immediately.

Then the engine would not restart. It would come close, but it just wouldn't. There is / was no smoke. No leaking fluids.

The car was not running hot at all. Oil pressure was strong. Oil is not milky.

It cranks but it's like it's starving for fuel.

Strangely, as time went on, it got closer and closer to starting.

Then, a few hours later, after having it towed to my MB dealer, it did start, but ran very rough. I quickly shut it down and now it awaits an inspection tomorrow morning (for me these things always happen on Sunday when everything is closed!)

I am worried that it's the dreaded timing chain and told the dealer my concerns because the car has 150k. So just 3 days before, the dealer installed a new chain tensioner.

I'm quite discouraged, as I just installed a new transmission and spent a ton of money on this car on so many other things I just can't count without going through my phone book of receipts.

I'm hoping it's some sort of tripped inertia switch for blocked fuel line, but with my luck, I doubt it...

You thoughts are greatly appreciated.
Thanks
-qcar

rivcal4life

Sounds like the upper wiring harness to me. It could have been jostled during your hard turn, then as the car cooled down, the wires could have contracted and changed position a little. Finally when the car was towed, that could have given you enough to get the car started.

qcar

Dealer says the timing chain came off rails (broken rails). I can either replace timing chain and rails and hope that there was no further damage to valves, etc. or go ahead and do a rebuild now.

Early estimates are $5-7k for rebuild.

Has anybody had timing chain / rail failure and NOT had valve and/or piston damage?

Thanks,
-qcar

rivcal4life

Maybe another person would be better qualified to answer this, but I would think that if the chain came off the rails, the car would not run at all. How do they know this is what happened? Did they remove your valve covers? If the chain jumped enough to cause erratic running, it would have bent a valve immediately and not run at all. I really find it hard to believe that is what happened, but I am only doing an internet diagnosis, so who knows. I would shoot over to www.500eboards.com/forums and ask the guys there for help. I still suspect your upper harness if it has not been replaced and has similar-to-exactly the symptoms you described. It is a very common failure. As in, EVERY 500E has to have theirs replaced, usually before 150kmi.

qcar

Thanks for your ideas. Very helpful.

I will look at the car tomorrow and see what's going on. The dealer said they found pieces of the plastic rail inside. But if they haven't opened up the engine yet, I don't know how they can say this for sure.

It's interesting that you say the car would not run at all if it was a timing chain problem with a bent valve.
-qcar

rivcal4life

My car also needs rails, it happens on many 500e. However, it does not produce the symptoms you describe. Even if your rails are bad, I do not suspect that fixing them will solve your running issues. If they found guide pieces in your oil pan, they do need replacing. However, your upper harness likely will as well.

qcar

Thanks for the idea. I will check the harness.

The mechanic has opened it up and showed me the broken plastic rail. His theory is that the rail broke and caused the chain to skip a tooth or two. He said the engine would still run (as it did), even if the timing was off.

He's going to do a leak down test and see if any of the valves are bent / damaged.

Maybe it's there are mechanical and electrical issues conspiring at the same time. I've always noticed that problems come in pairs.

Much appreciated!
-qcar

rivcal4life

Yes, the rails are often broken on these cars, and usually with half the mileage your car has. I've seen photos of a car with 75k and the rails were destroyed. I'm currently replacing my own in what free time I can find. However, I have never heard of an m119's double chain jumping a tooth. It seems very unlikely. Even without the rails in place, the chain should not have enough slack to allow it to happen. Unless it has stretched far beyond spec. It is definitely a logical mode of thinking for most cars, and if your mechanic is not familiar with the m119, I do not blame him for not checking the harness first. Either way, a leakdown test will provide valuable info on the condition of your engine, and your rails still need replacing. Just want to arm you with a bit of info before your mechanic tells you its going to take a full valve job to get your car running again and wants to charge you $4K for it. Good luck and let us know what you find in terms of the upper harness. If you need a procedure to check it, check out the website I posted above.

qcar

My service adviser called me with leak down test results: 95% leakage from cylinders #5 & #8,

Hopefully there's no damage to piston, cylinder walls or anything else. I should know more tomorrow when I talk to tech directly.

I assume tech should use a borescpe to look for further damage.

Hopefully, at this point, it just needs a valve job (plus new rails and timing chain).

Another mechanic said I should be okay, as long as valve didn't fall in. Even if the piston head has a nick in it he said it should be okay to reuse. This other mechanic also said I only need to replace the valve(s) that are damaged. Does that sound right?

Would a valve situation like this screw up anything else besides the piston head and cylinder walls?

I haven't addressed harness yet. This mess has overwhelmed me for now.

Thanks again!

-qcar