Cam timing expert help needed!
 

All,
Since I have done everything else I could think of to fix my smokey shaky 240D I have turned to timing and may have found something important. Using the not super accurate cam tower marks I show a stretch of 25 degrees ATDC. This tells me I am 1 tooth off. When I put the balancer at TDC the notch on the cam looks to be about 1 tooth , turning the cam CLOCKWISE from the front, away from lining up correctly. My injection pump is pulled to retard as far as the sloted holes will allow. The car starts ok, idles with a terrible shake in gear and smokes black/grey when warm in gear. Runs better than my 300D on the highway and has great pickup. Motor has 130k confimed on it. Good compression, motor mounts, yadda yadda. My question for the cam experts out there is this: Would the motor run, with no interference, with the cam 1 tooth late? Am I reading the signs correctly that I am in fact 1 tooth late? Can I spin the cam 1 tooth CW and fix my woes?Help! Its apart right now waiting for a gurus knowledgeable touch!

Yes, it will run without interference at 18 degrees retarded.

The signs appear to be correct, however, I would not use the tower marks as the final conclusion. I would perform a proper test using the 2mm valve lift method as specified in the FSM to be absolutely sure of the cam timing before I go start moving cam sprockets.

Then, the question remains as to where the IP timing is...........???

I have my dial indicator in the mail. But what your saying is that the dial indicator could tell me that 25 degrees ATDC at the balancer is ok, or even close? Seems so far out of wack that I didnt think it would be needed until fine tuning. If I move it 1 tooth forward, spin it by hand and it doesnt interfere, is there any reason i shouldnt try to start it and see what it does? The injection timing by using the welling up method shows about 7 degrees BTDC. However, the pump is all the way retarded in its slots already. That tells me its alos 1 tooth off but I wanted to get cam timing right before I play with that. Is this a bad plan?

I proved that the hard way. :D

If you trust the marks on the tower then go for it. Personally, I'd want the confirmation from the dial indicator before I made such a change, but, provided the engine will rotate by hand when you get done, you can't hurt anything.

Just be absolutely sure you know where you are now, so, worst case, you can return to this point if the marks are not proper on this engine, for whatever reason.

This question is purely acedemic but could someone explain how this happens? I can see a couple scenarios where the cam would jump a tooth like bad replacement job or turning the motor backwards. But how do I account for the seemingly 1 tooth off IP and the 1 tooth off Cam? Could someone have replaced the timing chain and had it come off both those gears? I guess Im just trying to find out what sort of monkey business could cause these symtoms in case there is something else thats been hamfisted.

For whatever reason people do not install chains and cogged belts correctly on a regular basis. Not worth thinking about really. Just correct the problem properly. I even examined a car they had put it on wrong on purpose to sell the woman more work. Something along the lines the car would explode if she took it from the dealership. I took a quick look and told her to have her lawyer give the dealership a call. Why should she pay me to rectify what she had already paid the dealer to do? Pretty sick out there and makes it pretty bad for the honest mechanic. If for some reason you cannot repair your own car start looking for one. They are out there but it is up to you to find them. You also want high skill level. Also watch personal recomendations. For some strange reason some people appear to like being abused. As strange as that seems. I have always wondered about that. When we were in business we always treated other peoples property like it was our own. We were always busy and people trusted us. Another strange thing was we also made far more money overall even though our billing was honest.

Well, seems like moving it a tooth to see how she goes it the plan. Aside from marking it so I can put it back, any advice on how to acomplish the move? I have to rotate the cam forward 1 tooth from under the chain. If I pull the tensioner and use cords to lift and hold the chain up will I have enough clearance or do i also have to pull the cam gear? Any neato tips or tricks for doing this with the least possible risk of losing the chain off the crank?

Endust,
I believe I know why the tooth problem happens on a regular basis...
In the Factory Shop Manual on changing the chain... it specifically states that " pressure must be kept on the chain" .... this with the fact that people do not rig up something to keep the chain DOWN at the cam sprocket ( there is a factory tool shown for doing that ) it is easy to skip a tooth due to gravity working on the load side of the chain while the oil pressure is not being supplied to the chain tensioner on the non load side...

Leathermag, The part that bugs me is do they not check their marks after changing and tensioning the chain or belt? Or do they know it is off after a quick check and just leave it? If that is the case it is just plain stupid or almost criminal if being paid for. .Tha engine is never going to run right unless there is enough adjustment to cover it. Usually there is not. Spun the crank pulley and belt drive cog after 200 thousand on my volkswagen the other day. For a second thought the crankshaft broke when I found the belt tight and not turning. There was just about the crudest engineered form of keyway engagement. It was just a stamped raised portion on the aluminum cog. It looks like the metal was just displaced from either side and bunched up. Of course it was wiped out pretty bad and soft aluminium as well. Just took a few minutes to drill for an interference fit pin and shape it to the keyway contour plus press it in. Usually german engineering is better. If it had spun out at speed rather than at morning startup I would have been looking for a new head at least. At low rotational speeds the hydralic valve lifters seem able to give enough to eliminate bent valves or other damage. The adjustable mechanical lifters do not have that much if any slop so inspect your chain guides periodically on your old 123s. If they fail by wearing out and the chain gets involved you will probably wish you had.

Still hoping for some advice on how to make this move. Im sure someone out there has done this before and has some insight.

Barry, I think what happens is that they don't look at the shop manual... or miss the part I mentioned... and they think " what could go wrong" since they are just hooking the new chain to the old... so they don't think they need to check it out afterwards...

I used two visegrip on both sides , step by step....

I'll write a step by step procedure for you.

However, I need to check some specifics with some of the fellows who have expertise regarding the slack in that chain.

Have some patience and I'll get you the info that you need.

That a common problem with the VW 1.9 (Canadian Version Non TDI) apparently it is a torque to yield bolt (IIRC its 60ftlbs PLUS 90 degrees) I did not Know the difference and near ruined an engine when mine backed off and 1/2 the keyway was wore thru, I was 4000kms from home. but 60$ later I was timed up and on my way