OM 603 timing chain........screwup.......

[Jmana]

Today was the day for the timing chain replacement. Thought the neighbor would be home to help me so I got everything torn apart, got the old chain apart, then he tells me his wife wants to go to the lake. WELL, the only person left to help was my 5 year old son. I figured I'd let him in charge of one thing - pulling out the old chain. I figured I'd keep a vice grip on the cam pulley, and just turn the crank, then move the vice grip. Well, the vice grip left go and the chain pulled down but I caugt it before it went in, but the old chain being oily, he left go of the damn thing I was able to fish it out with a magnet, but when he left go it sounded like something under spring pressure let go. Anyway, I got it out, and started to turn the crank again, but this time the cam pulley wasn't moving, so something down below slipped out of place and there must be slack in it somewhere. What the hell do I do now?? I still have the chain clamped to the cam pulley, back where it orgianlly was. Any advice would be GREATLY appreciated!!!

[Jmana]

Upon further inspection, it appears as if when the vice grip let go the IP gear pulled the chain down into the engine (it only went a few inches before I caught it) and it slipped off the crank gear. Does that sound right? Is it the IP gear that is under tension? Like I said, the chain is back in the same position on the cam gear, which is at TDC. The chain still seems to be under tension on the drivers side, so I am assuming that it didn't slip off the IP gear. The crank pulley is pretty much at the same spot it was before all this happened. If I drop the oil pan, would it be possible to pull the chain back onto the crank gear the way it was? I am sure this would be nearly impossible thought, right? Because I can't be sure the crank pulley is in the same spot. I did move it to see if the chain would pull through, but that's when I noticed the cam gear wasn't moving, so there is slack in the chain. I then moved the pulley back to the spot where it was. Please guys, I need any advice you may have.

[jrgslg]

I hate to say it but if it was me I would take the front of the motor off and start from scratch.This is something that must be exact and I wouldnt take the chance of losing a good motor.I truly hope someone else has a better answer to your dilema ,good luck.

This is exactly the situation of why I'd rather pay the extra money to have a MB shop do a chain job for me.

The chain is one of the only things I prefer not to mess with. I scared the begesus out of myself when I almost dropped the cam gear installing the offset woodruff key.

All I can say is get a flashlight and look very hard for anthing out of place.

[TWeatherford]

All I can say is I really feel for you and hope you get it worked out-let us know.

[Brian Carlton]

You've got a lot of work ahead of you.

The problem is that you don't know the timing of the cam or the IP with respect to the crankshaft.

So, your only choice is to start from the beginning.

If the new chain is installed, first see if the engine will rotate. If it does, then you need to set the crank damper to 0° and see if the marks on the camshaft tower are aligned. If they are close (and they will be if you can rotate the engine), then you'll need to adjust the camshaft until they are almost dead on.

Once that's done, then the IP will need to be checked to see if you still have that timing. If the chain came off the IP timer (unlikely), then it's even more of a chore to get it corrected.

[Jmana]

Well the thing is I never even began the pulling of the new chain trough. Everything is in the same spot where it began, I never moved the crank or the cam gear, so I know that the chain is at the same spot on the cam gear because the master link is at top of the gear. I don't think the chain came off the IP gear, because it looks like the chain guide would prevent that unless it had fallen the whole way into the engine, which it didn't. So basically I can pull the old chain on the passenger side up to the cam gear, but it's about 2 inches short, so I guess I can assume that there is about 2 inches of extra chain on the drivers side of the crank gear. I know the crank pulley is within 1/4 inch of where it was before this happened. My theory is if I can access the bottom of the crank gear, I can get the chain taught again and it should be able to meet up with the other section at the cam gear. So what's the best way to access the crank gear? I looked at the oil pan, and didn't realize it was so big. It looks like I'd have to pull the sway bar, and the little box attatched to the side. Is the gasket for the pan reusable? If not, can I use a liquid gasket? The problem arises that it's the weekend, and getting a factory gasket would not be possible for a few days.

[Jmana]

I wish I could go back in time knowing what I know now. If I had that opportunity, I would have put a vice grip on the chain that my son was pulling, that way if it slipped it wouldn't have dropped. Also, I screwed up royally by taking both grips off the cam gear at the same time. I should have kept one on the chain at all times, I think the ideal way to do it is to put a grip on the passenger side, turn the engine until that grip hit's the drivers side, then put another grip on the passenger side and only then take off the divers side grip.

[Brian Carlton]

Originally Posted by Jmana

Well the thing is I never even began the pulling of the new chain trough. Everything is in the same spot where it began, I never moved the crank or the cam gear, so I know that the chain is at the same spot on the cam gear because the master link is at top of the gear. I don't think the chain came off the IP gear, because it looks like the chain guide would prevent that unless it had fallen the whole way into the engine, which it didn't.

OK, take a step back for a moment.

Why do you believe that the chain has come off the crankshaft if you never did any pulling of the new chain and everything is in the same spot as where it began?

I don't believe that the chain will fall off the crankshaft on an OM603, so, your issues might simply be that the camshaft has rotated slightly and put slack on the drive side of the chain, thereby leaving you with insufficient slack on the tensioner side.

If you marked the chain carefully and the sprocket carefully, then rotate the camshaft and sprocket counterclockwise so that you can connect the ends of the chain.

[Jmana]

Well, I know the camshaft didn't move, the mark on the gear is still matched up to the mark on the tower. The reason I thought it came off the crank gear is I started to turn the crank pully, and the cam gear did not move. In fact I turned the crank pully about 30 degrees and still no movement, so then I turned the pulley ccw to get back in the same spot it was, which is when I realized the two ends of the chain weren't meeting. So apparently the chain can slip off the crank gear. Now that I am looking at the oil pan, I am realizing that's not going to be an easy job at all. Is there any other possibilities here?

[Jmana]

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.