M104 VVT Advance / Retard (Need Quick) - PeachParts Mercedes-Benz Forum

TROVERMAN · #1 10-16-2009, 08:59 AM

In the process of changing headgasket on 95 E320. In order to achieve TDC at the crank and with the two dowels, we had to turn the intake VVT to make everything line up. Which way do you turn to advance and which way to retard? Basically, the engine is at TDC now. Will I need to turn the adjuster the other way to retard upon re-assembling the engine or is it already retarded at TDC?

On a side note, how does the VVT work? (How does it adjust +/- 20 degrees)? I see two wires going to the cover of the VVT, that is it.

Need this quick, thanks

73Elsinore · #2 10-16-2009, 01:39 PM

The advancer is rotated clockwise if you are standing at the front of the car looking at the motor. All the way clockwise is full retard.

Make sure the cams are in the correct dowel positions, the crank is at TDC, then rotate the advancer clockwise to full retard by grabbing the sprocket (or the chain) and rotating it. After you do this, make sure the slack in the chain ended up on the tensioner (passenger's) side of the chain. If it didn't, you will have to monkey with it to get the slack on the tensioner side.

The tensioner must be handled correctly when doing this job. If it isn't, it will overtighten the chain and bust a cam when you start the motor because it is a ratcheting mechanism. The tensioner has to be disassembled and reinstalled in pieces to make sure the ratchet ends up on the correct detent because when you took it apart, the tensioner extended itself. It's all in the manual.

The cam advancer works off oil pressure.

Don't tell me you're trying to do this job without the manual?!?!?!?

TROVERMAN · #3 10-16-2009, 01:53 PM

Aside from being able to download a couple of helpful pages from the manual (finding TDC, cam dowel position, and torquing specs / pattern, yes doing it w/o the manual. At this point I already have removed the head, cleaned, installed new gasket, and reset head down. By moving the 'advancer' as you call it, we turned the big nut on the end, not the sprocket itself. Rotated the crank until TDC came up and used a couple of drill bits to lay flat on the head surface and into the sprocket holes. From the way the engine was when it was last running, I turned the big nut to make the timing marks line up. Right now the car has 115k on it. In March of 2006 at 82k we had a professional (indie mercedes master) do this job due to the oil leak. It is leaking again (we did overheat the engine once about a year ago, and the leaking started at that point) but all the timing marks scrawled into the sprockets and head are still there and all are lined up. The head is also flat, checked against a straight-edge.

Should I remove the tensioner completely and then reassemble it back into place? Why not just loosen and then re-tighten?

Thanks

73Elsinore · #4 10-16-2009, 05:26 PM

Quote:

Originally Posted by TROVERMAN

Aside from being able to download a couple of helpful pages from the manual (finding TDC, cam dowel position, and torquing specs / pattern, yes doing it w/o the manual. At this point I already have removed the head, cleaned, installed new gasket, and reset head down. By moving the 'advancer' as you call it, we turned the big nut on the end, not the sprocket itself. Rotated the crank until TDC came up and used a couple of drill bits to lay flat on the head surface and into the sprocket holes. From the way the engine was when it was last running, I turned the big nut to make the timing marks line up. Right now the car has 115k on it. In March of 2006 at 82k we had a professional (indie mercedes master) do this job due to the oil leak. It is leaking again (we did overheat the engine once about a year ago, and the leaking started at that point) but all the timing marks scrawled into the sprockets and head are still there and all are lined up. The head is also flat, checked against a straight-edge.

Here are a couple of very helpful threads that I recommend you read before you go any further:
M104 engine: Timing issue -one for the GURUS

http://www.peachparts.com/Wikka/M104HeadGasket

The sprocket itself is what you need to rotate, not the nut. It might be the same difference; I can't remember and I'm not near the car right now.

Quote:

Originally Posted by TROVERMAN

Should I remove the tensioner completely and then reassemble it back into place? Why not just loosen and then re-tighten?

Thanks

I don't think you can do that due to the ratcheting action of the tensioner. It takes up chain slack by moving outwards toward the chain and the ratchet mechanism keeps it from coming back. It clicks out (tightens) one more detent every time it thinks the chain is loose. That is why you can't loosen it or back it up. It has to be "reset" by completely disassembling it. It's not a big deal. The manual says remove it. Remove it and take it apart and clean it. Then you screw the body into the timing cover and then the impacting part goes into the tensioner body. The procedure is in the second thread, above. Replace the aluminum crush washer under the tensioner body. I'm not one to F around with what the manual says, especially knowing that too much tension will bust one or both cams, and those cams are about $400 each used.

Make sure you use the right sealant on the timing cover or you will be doing this job again a month from now...

latief · #5 10-17-2009, 11:24 AM

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

might be helpful

TROVERMAN · #6 10-19-2009, 07:58 AM

Sorry I didn't get back on the net since my last post. We finished it up Friday night. Its running fine, even at high RPM. No leaks, changed the oil. New problem: no climate control or reversing lights. I'm going to start a new post for this one, hoping its not the harness.