240d, auto

70mph normal highway speed, a lurch and bang, engine not running, coasting, select neutral coast off nearby exit ramp. Only sound was a light buzzing during coast. Very small amount (< 1 cup) of oil under front of engine oil pan. Observing from above no descernable damage or source of leak, small amount of oil splash in vicinity of front of motor. Towed to shop.

The lurch/bang was definately something snapping. When put into park it did lock the rear wheels, driveshaft appeared intact. No visible engine damage from above.

Any initial guesses or ideas?

Did you check the flex disc? Also, what's the level on your rear? All the old diffs leak in these cars. Differential could've locked up, bearing seized etc. How about the axles?

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Is the engine seized? Any recent work to the flex plate and/or torque converter?

Sixto
98 E320s sedan and wagon

I would try manually rotating the engine and dropping the oil pan to see if you find anything in there. If it won't turn, you could disconnect the drivetrain and see if you can find where it is bound up. I had a similar event which turned out to be my transmission spitting pieces of the casing out.

Dkr.

Read the post. He said the motor wasn't running.

May have thrown a rod.
May have a blown timing chain.

sounds like a broken rod.

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[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.

Sounds like a new car

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I agree on the timing chain.

Sounds expensive.

X3 on timing chain. Look through the oil fill cap, you can probably see the cam sprocket/chain.

Had two that broke chains, the valves were not bent but the cam towers broke. Put them both back together with mostly used parts and they ran well for years.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

It was a short snapping sound with a fairly firm lurch as you would expect if something stopped and then broke. Nothing sticking out the side of the motor or major oil leaking. And the bang was very quick, no banging, clanging, grinding, shaking, so I dont know if that would be timing chain/valves smashing.

Forgot to mention, about 140k miles on the motor.

I am wondering what the failure mode of the vacuum pump bearings would be like? I've heard it mentioned here but wonder whether a small auxiallary device could really grenade a motor.

Timing chain is extremely unlikely at 140K. It could have been the vacuum pump. My understanding is that when they go, the rubber diaphram gets breached and then you have oil in your vacuum lines. At this point, vacuum starts to get flaky.

I did have valve damage on my VW Tdi and it sounded much like you described when I was on the freeway, but that car has a timing belt and a lot of miles and VWs require frequent timing belt replacements.

Dkr.

Yeah, vac pump failure would cause that abrupt stop too and would be a lot more reasonable to repair than a broken rod.

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[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.

I think a broken cam and or the key to the timing sprocket. You'll see the motor spin but the cam won't if you turn it over by hand.

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CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

Main question, and already asked, is if you can turn the engine over by hand. On my 84 300D, I can use the bolt on the p.s. pump pulley (easier than crankshaft bolt). If it will turn and makes no strange noises, the engine is likely OK. If not, remove the valve cover and perhaps lower oil pan and see why not. When my 1985 wouldn't turn, I had to remove the head to find several pistons has failed, causing excessive drag.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans