When my son was driving from Tucson to Phoenix last weekend, he heard a loud clunk followed by a quick rise in engine temperature and unusual noises. He immediately pulled over and turned off the ignition. When the engine did not shut down, he raised the hood and used the manual shut off.

Attached is a photo of what he saw. The vehicle was towed to a repair shop. After removing the valve cover, they discovered the following:

1. The upper timing chain nylon guide rail was broken and parts of it had apparently lodged under the chain and bent the guide rail attach bolt.
2. The chain had skipped three links although there is no apparent damage to the camshaft or supports.
3. The exhaust valves each measured .018 (loose) but the intake valves indicated normal clearance.
4. The car did not "boil over" and there was plenty of oil showing on the dipstick.

The timing chain did not break. What caused the chain to break through the valve cover is still a mystery, although the timing chain tensioner is suspect. The timing chain and tensioner were replaced about 3 years ago.

If anyone has seen this happen before on a diesel and has clues as to the cause, your input will be appreciated. The car has @240K miles, uses no oil, and is well maintained.

Thanks in advance for your help!

Larry Campbell
1981 300SD (240K)
1979 300SD (325K)
1982 Chevy 1/2 ton P/U 6.2L diesel (202K)

Attached Files

HPIM0791.zip (55.2 KB, 201 views)

could you upload the pic to like photobucket.com or something i dont trust downloading files at all offline

Here's the pic.
People with macs have little to fear.

All I can say man is wow. Can't imagine what would have happened if the chain had broken.

Attached Thumbnails

 

__________________
'84 190d 2.2 - Silver
Converted to 5-Speed
'84 190d 2.2 - Blue
Factory 5-Speed

'76 300D (W115)
Sold, found again in less auspicious circumstances

OW. That looks painful.
Since it still ran after the event, you should be able to save it.

Not exactly the same thing, but this is my saga from a few weeks ago:

Stuck in NE - vacuum pump failed

My friends '85 380SE gasser did the same thing when a chain rail broke. I think that a piece of the chain rail gets between the cam sprocket and chain and doesn't clear the inside of the valve cover as it rotates around. I consider you VERY lucky. My friends 380 skipped more than 3 teeth, took out alot of valves and a piston. To say the least, his wouldn't restart
You WILL have to pull the head and surely replace valves but the fact that it still ran leads me to think that the engine is fully salvageable. Diesel pistons are increadably TOUGH.

In looking at the previous thread where He lost his vacuum pump, With what YOUR car suffered, I would definately check the vacuum pump also.

__________________
My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

He said the car also lost vacuum, I wouldn't be surprised if the vacuum pump was somehow involved, either as the cause of the failure, or as a result.

Engine is toast. Enough chain to bust a valve cover, a few teeth off and the car wont run. Tha vacuum pump is engine driven. You are going to need an engine. Dont let some yahoo shop put a chain in it and tell ya its good.

WOW....I'd like to know how you figured that one out??

He needs to inspect all chain related parts for sure but the engine never seized.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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I disagree he had to shut the engine off it did'nt quit on it's own I say it's repairable.

I bought a 1977 240D from a woman that had a similar thing happen. Chain broke causing 2 bent exh valves, 2 broken cam followers, cam broken into 3 pieces, but no other damage. I installed a later cam & towers, replaced the 2 exh valves & followers, all guide seals & did a valve job while I had it apart, put in a new chain & it ran like new. Just because it puked some parts doesn't mean it's all junk. Just make sure all the debris is removed.
I'd do a leakdown test to see if the valves are still seating properly. Compression test won't tell you much with the chain skipped, plus you run the risk of more breakage. If it passes the leakdown test the head won't even have to be removed.

I want YOUR Crystal Ball!!

__________________
My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

Do you work for a company that sells engines or something?

If it was still running after the incident and had to be shut off its obviously repairable.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Hmm sounds like the vac pump let lose, I'd inspect it. Unless the tensioner or rail just failed from age.


I think you 617 guys better start doing vac pump rebuilds.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

The mystery may be solved. Hatterasguy is probably correct. Thank you!

The oil pan was removed and a large piece of metal, along with numerous metal fragments, were found in the pan. Apparently, one of the bolts loosened that attaches the vacuum pump “roller-coaster” plate to the injection timing gear. There was damage to the vacuum pump, radiator fan, upper chain guide rail and valve cover. The vacuum pump damage was not initially discovered because pieces exited the bottom of the pump.

Attached are photos with descriptions below. Any other suggestions as to why something like this would occur will be helpful.

# 809: Bottom of vacuum pump removed from engine
# 810: Valve cover removed from engine
# 813 Fan blade
# 802 Destroyed vacuum pump along side replacement pump
# 807 Piece on left found in oil pan with other metal pieces. Bent bolt from plate
attached to timing gear
# 811 Replacement timing chain gear with plate attached by 2 bolts
# 814 Vacuum pump removed from engine. Note missing bolt top left of plate
on timing gear. It can be viewed in photo #807

Please see photos in next post.

Larry Campbell
1981 300SD (240K)
1979 300SD (325K)
1982 Chevy 1/2 ton P/U 6.2L diesel (202K)

Attached Files

	HPIM0810.zip (60.1 KB, 77 views)
	HPIM0807.zip (55.1 KB, 65 views)