thanks

I'm one of the amateurs here, but would it make a difference if the chain guide on the drivers side did not have both the upper and lower pins in place?

If the guide pushes the chain away from the center of the engine, that would rotate both cams slightly--maybe enough to make everything line up??????

The experts have spoken, both on this board and the thread on the other forum--I'm sure the information they provided about the TDC pointer is correct. I'm still trying to understand how I did this with positive results. I'm beginning to think it was dumb luck although I did mark everything prior to disassembly, then just put it back together the same way. I remember being somewhat unsure about the TDC crank position, but reasoned that it was that way when I took it apart so it must be OK.............

J. M. van Swaay

I think what has happened is that this head has been "straightened/machined " in the past when doing a head gasket.... therefor the dimensions are a bit different....anyhow, i hope what you are saying is right...maybe also the upper guide will tighten things up a bit..I still have to put in the guide rail pin although i doubt it will do much.....

I am very frustrated honestly with this... but not going to persue it more unless someone could think of a solution.....

thanks for the feedback ...

I think Dhaghighi was correct in what you should do, which basically is to forget about how it was set up (or seemed to be set up) and re-time it, correctly, from scratch. Pretty easy and the only way to be sure it's right.
Make sure you rotate it by hand several times afterward (with the tensioner in place) and that the marks line up correctly every cycle.

As far as the sensor/pointer bracket, my opinion is that when they introduced the M104 in '93 they shared some external parts with the retiring M103 until those parts ran out. So some early models may have the M103 brackets even though the sensor had been moved because the old brackets still served perfectly well as visual timing markers. When the factories ran out of the old stock parts they used newly designed M104 brackets. Or, perhaps they simply just used the old brackets until the new ones were available. Just a guess, but I think it's right. I think you said you do indeed have a 2.8, which I believe they only offered in 1993. So your engine would be a likely candidate to get a leftover (or temporarily used) M103 bracket if my speculation is correct.

No reason for the engineers to confusingly reset the timing alignment just because there's now a handy hole there where the sensor used to go.

thats the problem exactly, i re-timed it from scratch, and the timing is off a bit....

The problem
 

Thanks Long-Gone!

Latief I have been thinking, and I figured out your problem(2).

It is very simple. First of all, if you dont install the tensioner, you cannot read timing marks accurately....but you already know that now.

The next problem is actually simple to diagnose, because per your pics; after you rotate to check your marks, the dowel hole in your exhaust cam seems to have moved down equally to your intake cam moving up.

So your cams are timed ok relative to each other, but not compared to the crank.

The most probable culprit is that the slack on your chain is on the driver side when you installed your timing chain tensioner. So when the tension was applied, it pulled both cams counter clockwise to remove the slack on the driver side of your engine.

You really need to focus on getting the timing right AND getting the chain's slack to the passender side simultaneously.

You can use the torx wrench to manipulate the exhaust cam after you're sure about the intake cam (and the lack of slack on the driver side).
Then you should notice the majority (60-80%) of the slack on the passenger side at this point. Don't bother checking the dowel holes, because they will not read properly until the tensioner is engaged and the engine is turned.

the problem is that i have some slack on the driver side chain- exactly as you said. so when i rotate the engine, there is a delay for a moment until the chain grabs correctly. that causes both cams to be late a bit resulting in the situation i have....

the problem is how to get rid of that slack? which is not easy becuase i pull the chain hard before installing it on the driver's side, but it does not align properly with the intake cam in the retarded position when it is aligned according to manual ...
so what do you advice?

and what procedure do you use to install the chain correclty?

thanks,

Can you retard the gear slightly more or slightly less to get the chain on? I would think you couldn't be more than a half tooth of getting the chain taunt and it shouldn't get you too far off spec for degrees of retardation.

I don't know if this would be acceptable, someone with lots of experience with this procedure would need to verify.
I've heard the M104s can run pretty good even being a tooth off.

slack
 

If you turn the crankshaft counter clock wise approximately 10 degrees, and proceed with the procedure that you have been doing....

Then...turn the crankshaft back clockwise 10 degrees, back to TDC mark. This will remove the slack from the driver side. Install your tensioner and see where you stand. If you cannot time it correctly by trial-and-error, you might need to employ a mechanic.

latief - Did you ever get this completed? Did you figure out what the problem was?

I am in this exact situation, except I replaced my chain and guides also. Mine all lined up exactly when I lined up the I mark under the pointer, just as the manual shows. I even tried to insert a 0.002" feeler gauge between the drill bits and the top of the head and there was no gap. I somehow managed to get all the slack in the chain on the pass. side but I don't know exactly how I did that, it just sort of happened. I will now install the tensioner and see what happens. I still have to take the tensioner apart and clean it up first.

On a side note, it is interesting to note that to replace the upper chain guide, the manual says you first remove the tensioner and then you rotate the exhaust cam clockwise to slacken the chain enough to get the old guide out and to stick the new one in. This tells me that the position of the slack in the chain is one of the critical variables to getting the timing right.

What sealant did you use on your upper timing cover?

Let us know how it's going... thanks! Pete

It never was put in correctly.....I tried everything i could think of. something was not right with the setup....i tried advancing a tooth, it did not work either. i eventually just got it as close as i could, and bolted it back together.....car has been running great since September with no problems (related to this at least)....maybe it is not in its optimal setup performance wise, but i have no reference point to measure it against since this is my first mercedes

My thoughts (and steven brotherton's thoughts when i called him) is that the head had been shaved way to much in a previous headgasket job..who knows??

here is a link to my headgasket thread on the other forum.....

http://www.benzworld.org/forums/w124-e-ce-d-td-class/1460479-started-my-head-gasket-repair.html

it might be helpful....

good luck !!

Edit: The sealent number is my thread. it is mercedes sealent, and it has been holding out great since September....although i have not really put this car through a lot of driving since i have some other issues going on with it....

Right on, thanks for the update and good luck with it! Pete

Just curious, for the final setup, where did the timing indicater hole line up when the cam dowels were exactly on the mark?

J. M. van Swaay

I decided not to test-it and worry too much about. went by what the manual said, and what the people were recomending. put everything back together, and started it ....i did not try to check it after that and it has been running ok since then...i would imagine that the for the dowels to align properly, the TDC mark will be in the center of the circle on the TDC locater and not at the pointer where is should be......(you remember this whole debate, i am sure:)),

Latief,

I believe the correct answer to your question is that you must rotate the crankshaft through TWO full rotations before you can recheck the 4mm timing holes. The TDC must be on the compression cycle of the No 1 cylinder as opposed to the exhaust cycle.

I am presently struggling to find the correct procedure for my AMG M104 engine which apparently is different to the standard M104. I have tried a multitude of tests to try find the correct setting and have seen exactly what had you baffled.