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#1
04-21-2006, 03:53 PM
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Desperate (Timing chain question)
Hi-I have a 1985 300D turbo. I am replacing the timing chain. After feeding the new chain through and attemping to line the camshaft and crankshaft up several times along with the chain teeth onto the cam spocket. I have gotten myself a little loss. Right now I have the crankshaft on the 0 mark, but the camshaft mark is at 9 o'clock (facing the camshaft) the mark is almost 5 hrs. out from the other cam mark. I did move the camshaft several teeth while trying to line things up. I don't think that I had moved it that much to be that far off. But anyway. I am confused though. If the crankshaft is on the 0 mark does that mean the piston is at TDC for the number #1 cylinder or could it be TDC on another cylinder. Would I just lift the chain off the camshaft and rotate it to align the marks? Lets assume I have the camshaft and the crankshaft way off from each other. How would I align the crankshaft up TDC on the 1 cylinder and align the camshaft also TDC on the #1 cylinder and be sure that they are both align for the #1 cylinder.?
Thank You for your reply in advance.
__________________
Mike 
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#2
04-21-2006, 07:07 PM
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Quote:
If it's on the compression stroke, the mark on the #1 tower will align with the notch in the camshaft thrust washer.......give or take. If you've allowed the camshaft to lose timing with the crankshaft, I'd also be very concerned if you also allowed the IP to lose timing with the crankshaft. If this has occurred, I'll defer to those who have more skill than I do. 
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#3
04-21-2006, 07:35 PM
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Mike, The mark on the crankshaft pulley always indicates top dead centre of the number one piston only. Carefully see if you can get the cam sprocket back to its timing mark where it was by the shortest distance travelled by the cam sprocket. Or the cam sprocket turned the only way it will travel without jamming the valves to get to your cam mark. Should be the shortest distance. You are to not move the crankshaft position from top dead centre while doing this. Leaving the cam sprocket still bolted to the camshaft. Do not force anything. If you achive the above it almost sounds like you will have to deal with a injection pump out of time but perhaps not. Time also to read the archives. Post again when you get the above done so we can help suggest to you the best way to check the injection pump timing. One thing at a time. Just go slow without getting upset as you have not caused any damage. It might help to engage a knowledgeable friend if you are fortunate enough to have one. For others reading this thread. He has not gottten the crankshaft one turn out as valve interference would stop this happening. Still an easily manageable problem to some extent.
Last edited by barry123400; 04-21-2006 at 07:53 PM.
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#4
04-21-2006, 07:43 PM
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Quote:
The engine will rotate and start with the crankshaft out by 360 degrees in the cycle. Ask Pete Burton about that. 
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#5
04-21-2006, 08:17 PM
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country boy
i am just an old country boy
but it looks like if the crank shaft was out 360... or the cam shaft either one... looks like it would be back to its starting position... since there is only 360 degrees in a circle....
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#6
04-21-2006, 08:21 PM
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Quote:
The camshaft cannot be out 360 degrees relative to the crankshaft.
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#7
04-21-2006, 08:31 PM
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To duplicate this with an interference engine already together is probably impossible because of having to get through the valve interference obstruction. Actually the real risk is too get the injector pump and crank shaft sprocket one turn out on the crank shaft I believe in relation to the camshaft.
Happens when people do say head gasket changes? Or installing a replacement pump on an engine using top dead centre on the crank rather than using the cam mark as the principal refference. One could turn the cam 360 degrees in theory and be back where you where if interference let it happen. But it does not apply to the crank.. If the crank is rotated once it is actually 180 degrees out with the cams present location and the injection pumps as well as it has to turn twice to the cams and injection pumps turning only once. Again the interference should stop that senario as well.But still possible with the injection pump. Clear as mud or have I made a misteak? Think about it and correct me as it is the best learning tool. This posting is not for the fellow doing the relocation of the cam sprocket unless it helps him in understanding. This area is why a previous poster was cautious about getting involved I thought. When I reflected for a second or two I realized it was not a current issue with him. The valve interference just inhibits it happening. I could be wrong about the motavation of the poster or even the above but probably not. Never offer advise that I would not do myself is super important. If it is wrong it should be corrected. How else do I learn. Last edited by barry123400; 04-21-2006 at 09:01 PM.
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#8
04-21-2006, 08:44 PM
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Quote:
Set the camshaft in a given position.......with the cam marks lined up perfectly and the engine crankshaft at 0 degrees (no chain stretch). Now, magically rotate the crankshaft by 360 degrees and leave the camshaft in the same position. All the pistons move to the exact same positions as they were before you rotated 360 degrees. When you look down and read the crankshaft, it will again read 0 degrees with the cam marks lined up. When you rotate the engine by hand........there will be no interference with the valves. The crankshaft and camshaft are in perfect harmony. Unfortunately, at this point, althought the crankshaft and camshaft are perfect with each other, the IP is out by 360 degrees and it's injecting fuel on the exhaust stroke.
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#9
04-21-2006, 09:12 PM
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Brian, thanks for the clarification of what I was trying to convey or a better graphic description of process. I have spent the last few minutes trying to clear up my post a little while you were generating yours. The main point I thought was since the interference was an absolute between the crank and cam movements with an assembled engine. He will only have to be guided on the proper positioning of the inkjector pump timing in relation to the cam as I suspect it"s position may have floated off somewhat in his struggles. That I felt could be dealt with later if required. I want to see him get the crank and cam marks back on first. He should manage that with clear definitions like you are presenting. To have incorporated the second stage might have been just too much for him initially so thought the division was sound. Positioning of pump and drip test might still be on his agenda soon. Anyway we describe it he will get back just by following instructioins along the line not even having to absolutley know the otto four cycle principal in effect. But anything he does absorb is a plus.
Last edited by barry123400; 04-21-2006 at 09:25 PM.
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#10
04-22-2006, 10:58 AM
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Thanks guys. So for right now all I have to do is lift the chain off of the cam spocket and rotate the camshaft to align the marks up. Temporay connect the chain, rotate the crankshaft one turn and check for both alignments.
__________________
Mike
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#11
04-22-2006, 11:10 AM
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Quote:
You're not going to be able to rotate the camshaft very far because a valve will hit a piston. I presume the rocker arms are still in place? Additionally, you need to maintain upward tension on the chain at all times. This means a bungee cord from the garage ceiling. You must manipulate the camshaft sprocket into and out of the chain while maintaining that upward tension to prevent the loss of the chain from the crankshaft sprocket. I'm assuming that you have removed the tensioner from the side of the head for this procedure?? Quote:
Last edited by Brian Carlton; 04-22-2006 at 11:22 AM.
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#12
04-22-2006, 11:11 AM
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Its the same way in a distributor type gasoline engine. The cam can be timed correctly to the crankshaft but the distributor can be off by 180*. A timing light will show the distributor at the correct timing but it can be off 180*
Of course it much easier to change the distributor 180* than an injection pump, especially distributors that have only two notches to slip into. Its either right or out 180*, not in between like the gear driven distributors on the old Chrysler slant 6 engines. They are more difficult to put in correctly because the gear teeth have to be lined up correctly. Don't ask how many times I found this out (damned plastic gear). P E H
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#13
04-22-2006, 11:14 AM
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Quote:
The best way to solve this problem is to remove the cam-followers - after removal of the cam-followers all valves will be in the fully closed position and no piston-valve interference will occur. You can then rotate the camshaft to the proper position reconnect the timing chain and reinstall the cam followers. As Brian points out you also going to need to check/set/verify the injection pump timing.
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#14
04-22-2006, 11:19 AM
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I am at work right now. The mark on the cam is at 9 o'clock so I would have to rotate it about a half a turn. I did keep tension on the chain while feeding the new chain on. The first time I feed the chain I kept the old tensioner in place, but the second time I removed it.
__________________
Mike
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#15
04-22-2006, 11:35 AM
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Mike,
That's why U should always have two people to change a timing chain. Three is even better. I don't know how U could feed the new chain in, turn the engine and pull out the old chain doing it alone. P E H
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