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Old 08-27-2006, 10:14 PM
Jmana Jmana is offline
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Join Date: Sep 2005
Posts: 598
Smile Timing Chain - Lessons Learned

Thanks to all the help here, I have completed my timing chain on the 87 300D (603 engine). There are some things I learned along the way, and wanted to post this so that anybody attempting to do this proceedure feels comfortable doing so. I speak only for the 603 engine. The first and most important thing I learned is after you cut the old chain, to make sure to ALWAYS have a vice grip to hold the chain going into the engine onto the cam sprocket. It doesn't have to be super tight, just tight enough so the vice grip doesn't fall off when you turn the crank. You will need 2 vice grips to do this. Put one on the chain at the left side of the cam sprocket, and as you turn the crank it will end up on the right side of the sprocket. Don't take it off, use the second vice grip to clamp again to left side, after it's on you can take the first grip off. Just keep doing this the whole time, and you won't need a 2nd person, and you won't have to worry about the chain being pulled into the engine. Now, the other thing is, once you cut the chain, and hook the new chain to it, you really don't have to worry about it falling completely into the engine. In fact, even without the new chain, if you have at least 6 inches of chain it will not fall completely into the engine (unless you keep turning the crank) because the guide and IP gear will keep it from doing so, so you really don't have to worry about that. Also, it helps to put a 3rd vice grip on the end of the old chain that is now coming out of the engine, this way you don't have to worry about it falling into the engine. Even if it does fall in, don't panic, get a magnet on a stick and a long skinny flathead and it's easy to get out. As you turn the crank, it isn't necessary to keep pulling on the chain as it comes out, just give it a turn, move your grips around, and pull out the slack.

Now, if for some reason the grips come off and the chain gets pulled in and you don't know where you were on the cam sprocket, don't panic. If this happens DON'T turn the crank any more. It may have turned somewhat on it's own, either forward or backward because of compression, but don't turn it and make it worse. What you now need to do is to pull the chain back as far as you can and get it back on the cam sprocket. If you do this you won't be more than a couple teeth off, which you should still be able to turn the engine. Keep putting the new chain on, and once it's on check to make sure everything is TDC. If not, get the cam at TDC and check the reading on the crank. Since mine was about 40 degrees ATDC and off by 2 teeth, you can kind of gauge how many teeth you are off by (I guess 20 per tooth). Now you need to have the master link on the cam sprocket, while the crank is at TDC, so you may have to turn the engine over several time to accomplish this (hopefully you aren't so far off that the engine doesn't turn). Once you get it to that spot, take off the master link, mark on the sprocket with a marker where the link is, put a vice grip on both ends of the chain, lay the passenger side of the chain off to the left. Now get a socket on both the crank and the cam and pull the crank counter clockwise and the cam clockwise until they are both at TDC. And then pull the drivers side of the chain over as far as you need to get back the teeth that you skipped prior, and get the chain on the sproket. This may take some hard work. On mine it would get halfway between the teeth, and I couldn't get it that last half a tooth. But I kept adjusting the crank backwards and cam forwards until I was able to get it two teeth back (where it belongs). Now use the grips to hold the two ends of the chain on the sprocket (don't put the link back on yet) and turn the crank backwards a little past TDC, then forwards and see if the cam moves to TDC as the crank does. If it does, you are golden. Now this is a complicated proceedure, but keep in mind that if you keep the vice grips on the sprocket in the first place, you will never skip any teeth, even if you are doing it yourself.
87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head
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