Several years ago i removed the engine from my 1985 300TD turbo euro car and rebuilt it, new cyl liners pressed, pistons, bearings, pretty much everything.

Its been driven less than 10,000 miles now and it has developed a rattle that is only present at hot idle, raise the engine off idle speed and the noise goes away. Noise is NOT present at cold idle. Its not a knocking noise, of a injector noise, its erractic slapping type rattle, like the chain knocking around in the engine really.

I removed the lower oil pan, half way expecting to find the oil pump chain tensioner broken or something due to its cheese design, however the oil pump chain and tensioner is ok.

Heres what i found, with a long screw driver i can reach up to the crankshaft sprocket and found that the timing chain itself has a lot of looseness on the drivers side where it goes up to the timing device for the pump. The timing chain will move up and down atleast 1/2 inch. I cannot see either of the plastic guides unless i remove the injection pump timing device, but i found no broken plastic in the oil pan which leads me to believe the guides are ok. Really hoping i dont have to remove the engine and take it back apart again.

The timing chain was new, less than 10,000 miles ago, as well as the tensioner and all guides. My question is, why would the chain be so loose on the drivers side on the crankshaft sprocket, i know the tensioner is on the other side, so this technically is the "loose" side, but i feel this is excessive. I removed the valve cover, chain seems tight on the cam, maybe cause thats the side that the tensioner is on? Not sure really, any thoughts would be appreciated.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

I don't have an answer. But, are you sure that the noise is not from the Vacuum Pump having issues.
You also might want to remove the valve cover and inspect the full length of the chain for pins coming out and or damage to gear teeth.

When I had a sound that sounded like a timing chain sound I found that the upper chain guide that is on the drivers side was loose and rattling. See number 89 in the attached picture.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

Ck the crank gear for movement on crank,poss.key and groove damaged.

Well its back together today and running, noise is gone im so thankful. Heres what happened, hopefully this will help someone else in the future.

The chain tensioner is supposed to ratchet out and lock into detents on it own. Well this brand new tensioner was stuck in the 1st detent, i guess oil pressure and the spring alone was not enough force to get it to pop into the second detent. I removed the cap and spring from the tensioner, turned the camshaft backwards to take up all the slack in the chain that was on the drivers side, so now the slack was on the tensioner side, then took a brass drift the same size as the piston of the tensioner and knocked the tensioner out in the second detent where it locked in tight. Reassembled everything, verified injection timing with AB light, was off 1 degree, so not a big deal. Drove vehicle and got it hot, noise resolved. All because that tensioner would pop out to the 2nd detent without a little extra force. Hopefully this will help someone in the future.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

The tensioner is a good part to get from the dealer. Ill bet yours is an aftermarket unit. Keep an eye on it. Even the Febi afyermarket unit has reported issues.

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Chris
84 280sl
82 300d euro

Thanks. That was my thought. In old tensioners, the internal spring is usually worn flat on one side, and thus lower in compression force and could break altogether. A new one is cheap here ($7). I don't know that the spring is essential since there is also oil pressure on the piston. Perhaps the spring is just for initial assembly.

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

I don't know about this engine specifically but, many tensioners have a pin or other holding mechanism that must be removed after the tensioner is installed. This prevents the tensioner from over extending ( and locking ) prior to assembly preventing too tight of a chain.