Broken Cams,Timing Chain on 95 300Diesel - PeachParts Mercedes-Benz Forum

DieselinBlood · #1 12-11-2006, 12:21 PM

Riding home Sunday afternoon on the interstate,cruise on at 70mph-BANG! had to be towed home. I looked in the oil fill cover and saw the timing chain was broken. taking off the cam cover to get at the chain I find both cams are broken and some of the bearing brackets are broken. This is a 1995 E300 Diesel 606 engine and has 169000 miles on it. I don't know what broke first, the chain or one cam breaking the bearing mount jamming the other cam causing it to break and breaking the chain. I'm also wondering if the chain were to break throwing the cams out of alignment and causing the pistons to hit the valves breaking the cams. If that was the case the motor is trashed. It cranks fine so the engine is not seized. Does anyone know if the pistons will clear the valves if out of alignment or hit? Its gunna be expensive, just how much! Jim

Ken300D · #2 12-11-2006, 12:37 PM

I would say the motor is not necessarily trashed, but you are surely looking at new cams and some valves. Once the head is pulled off then the condition of the pistons can be evaluated.

Was that the original timing chain?

Ken300D

DieselinBlood · #3 12-11-2006, 12:44 PM

I don't know the history timeing chain .I've owned it for a year and put 19000 miles trouble free on it till now Jim

#4 12-11-2006, 12:58 PM

That is either terrible misfortune

OR, someone sold you a car with incorrect odometer.

There is NO WAY that a timing chain should fail on that motor at "only" 169K. No way, no how, unless you're simply the victim of bad luck.

Good luck - it is most definitely repairable, but I feel for you.

mplafleur · #5 12-11-2006, 04:13 PM

The motor is not trashed. Certain part are though. It is completely rebuildable. I've done two from broken timing chains.

What happened was the timing chain broke. This caused the pistons to come up on the valves that were still open and instead of only bending the valves, the camshaft and cam towers broke. In this case, the cam tower is supposed to break before the cam, thus saving the camshaft. This is not always what happens.

My first timing chain break was at ~230,000 miles and I never found a root cause. The chain may have just failed. It only bent valves and the rebuild, including new oil pump, intake valves, exhaust valves, valve guides, seals, chain guides/rails, cost about $1200 to do.

The second chain break happened at ~200,000 miles I believe. It broke the camshaft into three pieces. I got a used head and rebuilt the engine for about $400. Root cause was a failed vacuum pump.

Shorebilly · #6 12-11-2006, 04:56 PM

If you didn't bend any valves when it broke......if the 606 has an interferance piston/valve fit....then cranking it did not help the situation any!!!

SB

Hit Man X · #7 12-11-2006, 05:12 PM

I can assure you the head is going to take some cash to repair. Probably bent most of the valves, damage was done when it broke... not when you tried to crank. Guides, seals, etc.

I'd budget $700-900 at minimum to do the head.

Probably $600 in misc parts (chain, seals, gaskets, bolts, etc).

No clue what those cams will run, $500 a pair sounds reasonable.

I'd probably just pull the motor to rebuild it, you'll be able to work and reseal everything FAR easier. But, before that... evaluate the entire vehicle. Is it worth all the time and labor? This would probably take me a few weeks workin most of the day to complete.

Sure, '95s are hard to get... but it simply not be worth it if your time is more valuable than your money. Unless you of course do this as a hobby.

aklim · #8 12-11-2006, 06:15 PM

Should the timing chains be changed as a precaution when it gets to a certain mileage?

Hit Man X · #9 12-11-2006, 08:13 PM

Quote:

Originally Posted by aklim

Should the timing chains be changed as a precaution when it gets to a certain mileage?

The guides are more of an issue. Each broken motor I've come upon has broken upper guides.

Seems chain stretch happens with infrequent oil changes.

I figure after 150K you may as well swap the chain, the amount of cash involved versus shelling out for a new top end is minimal.

engatwork · #10 12-11-2006, 08:39 PM

I've got a friend that has the same car with over 200k miles on it and I'm sure is on the original chain. Is there anything to check/inspect to verify it needs to be replaced? Should I just advise her to go ahead and replace it (along with the guides) between now and 250k miles?

I have noticed when driving the car that the hot idle oil pressure is less than 1 bar

. Do the oil pumps get tired on these engines?

Hit Man X · #11 12-11-2006, 08:47 PM

The guides are the issue as I stated. The nylon or what-have-you they're made of just doesn't last forever. They can snap easily, and do!

You could just pop the cam cover and check out timing stretch to see where it's at currently. 2-3° is a-okay by factory as I understand. After ten years/150K it would just be smart to do it. I don't see it running more than $500 at a shop even with a huge mark up on parts.

On the 616/7 as well as 601/2/3 you have to pull the balancer, crank pulley, etc to get to the tensioner rail or the lower guides. So I'd just replace that upper rail as it's the easiest to get to and causes the problems. Do the tensioner too while you're in there.

Do the other guides when you replace the front main, chances are... yours leaks too.

Gas motors are easy to do all four upper guides (including the tensioner rail). I'd spend about 6-8 hours doing those plus the chain install with new tensioner.

What oil is used in the vehicle? Should have a fairly heavy oil in there.

engatwork · #12 12-11-2006, 08:55 PM

Delo 400 is what she has been running in it since around 180k miles (when she found me

). I'm not 100% she did that good a job of keeping the oil changed at timely intervals or even if she ran diesel rated oil up to that time. She is the original owner. Pulling the cam cover will show in the form of sludge build up. I've already replaced the front main seal on the car.

mplafleur · #13 12-12-2006, 02:08 AM

Quote:

Originally Posted by engatwork

I've got a friend that has the same car with over 200k miles on it and I'm sure is on the original chain. Is there anything to check/inspect to verify it needs to be replaced? Should I just advise her to go ahead and replace it (along with the guides) between now and 250k miles?

I have noticed when driving the car that the hot idle oil pressure is less than 1 bar

. Do the oil pumps get tired on these engines?

I had low hot oil pressure. Changing the crank bearings fixed that.

#14 12-12-2006, 02:34 AM

With all that visible damage, WHY did you crank it?

That's like breaking your leg and then trying to stand up.

mplafleur · #15 12-12-2006, 08:44 AM

I don't think cranking would do any damage. It's already done.

When the chain breaks, the engine is already spinning at a few thousand rpm. That'll make sure it's non-interference...

When my first chain broke, I tried to restart the car. Who wouldn't? I didn't know what happened and I was still a few miles from home at my freeway exit. I did notice that it cranked a little faster though.