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Old 09-02-2003, 08:31 PM
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Join Date: Feb 2002
Location: michigan
Posts: 34
Unhappy Death of beloved 300sd

Well a sad day guys my 300sd died a painful death today. I was comeing up to a stop and suddenly I heard a horrable noise. I pulled over and shut her down but it was no use.

Upon reaching home I removed the cover over the cam and discovered the cam broken in half and the chain guide rall broken.
Which happened First I can only Imagine.

I know she was not much to look at but she really ran nice up until today.

Does any one have any idea what would have caused this? even With the cam broken I can still move the engine with a wrench so it didnt seize, plenty of oil ,valves were adjusted? Is she worth fixing I have another head.

Thanks for reading Pat
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Old 09-02-2003, 08:45 PM
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Join Date: May 2003
Posts: 2,220
Sounds like the timing chain broke. Replace the cam, chain, chain tensioner, and chain rail. That's all that should be damaged.

The head should be OK.

Good luck,
1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)

Last edited by DslBnz; 09-02-2003 at 08:52 PM.
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Old 09-02-2003, 09:51 PM
Senior Member
Join Date: Feb 2001
Location: Canton,Texas
Posts: 987
My guess is that the chain guide broke first and the interfernce of the pistons meeting the valves broke the cam. I would guess you'll need new valves. The pistons may be beat up pretty bad but you can see them when you pull the head. They (the pistons) will probably be ok but hopefully someone who has rebuilt an engine will chime in pretty quick and tell you how bad is too bad for them.
1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k
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Old 09-02-2003, 10:00 PM
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Join Date: Nov 2002
Location: Wakefield, RI
Posts: 2,145
Now that sucks! However you are in the middle of the rustbelt. Finding a good used engine in a boneyard shouldn't be too hard. If you have time on your hands and the head it may be worth your while to tear into it. My money would be on an engine swap though. $200-$500 should get you a decent engine. Try the smaller more rural boneyards. The prices tend to be better. RT
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K
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Old 09-03-2003, 01:34 AM
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Join Date: Jan 2000
Location: PA
Posts: 5,440

Your 300Sd is not be dead, just wounded.

What happened is that the timing chain jumped, maybe because the chain quide failed, and the pistons hit the valves and one of the valves hit the cam and broke it.

Same happened to me in a '64 190D. All I had to replace was the cam, cam towers and timing chain.

Most likely the cam towers are broken too. I think they are designed to break to protect other parts of the engine like the valves, pistons, and camshaft. But sometimes it doesn't work and other parts are damaged.

You should be able to put the engine back in running condition by replacing the cam, cam towers, timing chain, chain guide and valve seals. Most difficult part of the job is to time the injection pump (IP). Put punch marks on the IP and housing and you should be close on the timing. If engine runs OK, as mine did, you won't even have to pull off the head. If it doesn't run OK, you might have to pull the head and replace some of the valves.


Last edited by P.E.Haiges; 09-04-2003 at 11:12 AM.
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Old 09-03-2003, 06:49 PM
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Join Date: Feb 2002
Location: michigan
Posts: 34
Thanks for all the Info

Thanks guys I really appreciate your imput. I will do some further under hood investigation. and post back.

Thank you

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Old 09-03-2003, 09:18 PM
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
My brother tossed the crank in his 75 300D (617 engine) on the highway at about 65. Blew holes in both sides of the oil pan and cracked the block, but the head was fine. So were the valves. Even the cam survived on his, but all three cam towers were busted.

New cam and towers and chain plus guides, IP timing fix, and you are ready to go. Crank over by hand once you get the chain and cam in and see if the valve operate normally -- if you have excessive clearnce or some won't come back up, it's valve job time.

Most likely there is no other damage to engine.

I'ts also possible the cam broke first and everything else came later...

1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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