syn cam and crank on '87 260E

I became encouraged after reading all the posts concerning worn guides/seals on this 103 motor. I figured this high mileage car would be great for another 2 years for my daughter so I tackled the job. i got the head off and back on OK. The problem is although I think I understand how to "align" this motor, I'm not certain I got it right and I don't want to do it over again. The procedure (as I understand it) is to have the crank at TDC and then the cam hole should be lined up with the boss on the bearing cap. I think I'm off a little. I have already installed the new master link but I did not yet peen it over. Where can I get the tool to peen the link or does pressing the link on assure that it will stay there? Lastly, what is involved in aligning the TDC sensor. I disturbed it removing the har balancer and I can see it is adjustable. I would appreciate whatever help you can give me for I am ready to bring the whole car to the dealer.

[jeffsr]

Make sure the crank is at TDC on power stroke for #1 cylinder. There are two TDC's for each cylinder 360 degrees apart. Check the timing marks on the harmonic balancer. You probably should have marked the 0 degree line when aligned with the left edge of the TDC sensor before you took it apart. With the cam aligned with the mark on the bearing boss, you'll need to put the rotor on the rotor shaft and see if it lines up with the #1 position in the distributor cap. If it does, then your are on target for TDC, if not then you'll have to rotate the engine by hand until you get there. Make sure the the chain tensioner spring has been removed from the tensioner well. Adjust the position of the timing chain so the cam and the crank are in synch. As far as the chain goes,the link pins can be peened over by backing the link pins with a piece of flat heavy metal and tapping the front of the pins with a ball peen hammer. Do not put it back together w/o peening the pins over. Make sure you replace the spring in the chain tensioner. Also, align the left edge of the TDC sensor with the 0 degree timing mark. Hope this helps.. Rmemeber, always mark things that are critical reassembly parts, so you won't have to guess at it later on.

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[Benzmac]

A couple of words of advise. After the chain is on correctly, turn the engine over with the bolt on the front of the crankshaft.(27mm).

PS If you have had the tensioner out, you MuST take out the piston and install it back in the front. It is a click type and will ruin the bow rail and the chain in a hurry. Be sure to do this before reinstalling the spring. It will self adjust (When doing this you will put it back in untill you hear one click.)

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Jeff, thanks greatly for the response. The cam turns 2x as fast as the crank, right? So at one 0 degree mark the cam hole won't be in line with the boss, right? Then I would turn the crank 360 degrees which would then line up cam.I'll know better about marking the location of the TDC next time.

thanks again for all your help.

[This message has been edited by Webmaster (edited 04-22-2000).]

[jeffsr]

If you look at the cam sprocket and compare it with the crank sprocket, you'll see that the cam is driven at 1/2 the speed of the crank. This has to be as when #1 is on power stroke, the valves stay closed until just before BDC, then the exhaust begins to open and stays open until just before TDC on the exhaust stroke. Same with the intake. Closed at TDC on the power stroke, stays closed until just before TDC on exhaust stroke. If the cam were turning at 2x crank speed, each valve would be opening twice on each power and exhaust cycle. Each valve has to be open only once in 720 degrees of crank rotation. What you have to be sure about is which TDC your looking at when you do the final setup of the timing chain. Basically three things have to be in synch. #1 is at TDC on compression stroke, the cam is aligned so both valves are closed at that point. You can usually feel some slight play at the end of the valve lifter. You can also see if the cam followers are on the flats of the cam base circle. And, the rotor is sitting at the firing position for number one cylinder on the distributor cap. Another tip is if you look at the engine from the front, it rotates clockwise. If #1 cylinder is at TDC on compression, check the position of the cam lobe on the exhaust valve, it should be approximately 180 degrees away from the cam follower because that valve doesn't open until the crank has traveled all the way thru the power stroke and is beginning the exhaust stroke, i.e. heading back towards TDC. Hope this helps. Remember 3 things need to be in harmony, the cam, the crank and the ignition. With this done, you will have good Karma and your Benz will love you. Many folks get flustered with all the hoopla about this procedure. If you sit down and think about it, it's not too hard to figure out. Happy motoring..

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Jeff L
1987 300e
1989 300e
1987 BMW 325