Yesterday afternoon I got ready to change the timing chain on my 1981 240D. I removed the fan and shroud and the glow plugs, then the valve cover. I checked the timing chain wear and it was at 5 degrees retard. This aft., I got ready to actually do the change. I removed the tensioner and the plastic guide. I grounf off the heads of the chain pins, and fastened the new chain to the old. I held on to both chains while my helper cranked the engine around with a socket on the damper nut. I held as tightly as I could, but it is possible that one or the other of the chains jumped a small amount. At any rate, we got the new chain nearly all the way around, and fastened together with the new link(not peened yet). About 90 degrees from having the new link on top of the cam sprocket, we could no longer turn the engine over. The chain was tight on the drivers side. We can move the chain about 30 or 40 degrees total, back and forth, but no further. Haynes manual says engine must now be disassembled to correct this situation. I have searched the archives but found no help. I did hang on tight to both ends of the chains while turning the engine around. Does anyone have any good advice for me? Thanks to all.

Dear davidg:

There's a possibility that the chain was not jumped at all. Perhaps the feeling that you could no longer turn the engine was just caused by the high compression generated in the cylinders.

Try to loosen the glow plugs or diesel injectors to release all the compression and try to turn the engine again.

Be sure to put the gear in Park or Neutral.

Eric

glow plugs were removed,engine turned over easily, although compression was detectable.

It only takes two links out of time to make these engines have piston/valve interfearance problems.

Engine disassembly will not be required to fix this one - Turn the engine until it jams (I assume you are turning it in the proper direction - clockwise as viewed from the front of the engine...)

When you get it to the jammed position look at all the cam lobes - find the lobe that is depressing a valve the greatest amount and then carefully remove the chain from the cam and move the cam ONE link in the direction that will cause the valve to lift. This will provide clearance for the piston.

This will most likely get the engine turning again. If this does not work you will need to remove the cam and then spool in your new chain.

When you get the chain back in you are going to want to set/check the valve timing and the injection pump timing.

davidg,

So is the engine running OK now?

P E H

thanks, Tim, I will give your sugestion a try tomorrow. I think I made my mistake by removing the chain guide and tensioner prior to feeding in the new chain. With the new master link about 90 degrees from where it was supposed to be, I could not see the timing mark on the chain sprocket where I thought it should be. Your answer makes sense. Thanks again, and I will report on further developments as they occur. davidg

You moved the tensioner guide rail? Got the whole front of the engine torn down? Usually all you should have to remove is the tensioner itself.

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Jim

I removed the tensioner and the plasti guide that pivots on press fit pin and is anchored to the head beneath the cam sprocket. The only things I have removed from the engine are the cam cover, thermostat housing and the tensioner.

davidg

I had the same problem. You can get the cam back in sinc with the timing marks by bunching the chain one link at a time over the cam sprocket. Of course like Tim said, you will have to time the IP.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Success! I finally cot the cam back in time and the chain pinned together. By cranking it around by hand several times, it comes up about 1/2 or 1 degree retarded, a big improvement over 5 degrees off when I started. It took me a while to figure out how to jump the chain over the sprocket, and then I got confused and went back the wrong way and got bound up again, but I finally prevailed. Many thanks to those who replyed to my post. davidg