If you can't turn the engine over by hand turning it over w/ the starter will be Bad.

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I am not sure i understood that. my question is that while messing with timing, at one instance the valves did touch the pistons for a second. i unbolted the cam to reset everything, and after that everything was fine again. do you think that during that brief encounter, damage might have occurred? this was during rotating by hand with the tensioner off....

thanks for your feedback thus-far...

best,

Latief

No, touching a valve while turning over by hand won't hurt anything.

Jonathan

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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

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles

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.

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.

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

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.

This was resolved. the issue was 4 degrees of chain stretch causing the dowels to be slightly off.

according to the experts here, anything under 5 degrees stretch is within the normal wear and tear range, more than that you will need a new chain and guides .....

Thanks for the response....that is an interesting engine that you are working on. good luck !!

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1993 300E, 2.8 M104 .....

Hi latief,

Thanks for the reply. I understand the chain stretch effect on the basic settings.

But, the point that I was making was that the timing holes only line up every second revolution at TDC.