M117 Timing Chain. When is it Done?

[73MB280SEL]

I have a 73 108 bodied 280 4.5 that I've had for a few months. I had the valve cover off last weekend and cranked the engine over by hand. At each cranking, I checked the timing chain for wear and cracks. I couldn't see anything obviously wrong with the chain, but I saw no master link either (could the chain be original?).

The only sign of obvious wear is that all the links were polished on the top surface where they slide against the tensioner. I have no idea when it was last replaced if ever.

I did position the engine at TDC cyl 1 and check the timing marks on the camshafts. They appear to be in alignment or pretty close. That's if you believe that the TDC mark on the balancer is correct. I do not have a spark plug dial indicator mount to do TDC accurately.

Should I just replace it? Is there something else I should be looking for?

How bout the slide rails. Is there something I should be looking for with the valve covers off? The looked pretty fresh from what I could see.

Sholin

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Lt. Blue 1973 MB 280 SEL (108) with sunroof and console shift.
1996 Chevy Camaro Z-28 LT1.

[This message has been edited by 73MB280SEL (edited 11-04-2000).]

[Aaron]

Sholin,

Depending on mileage is the big question regarding chain replacement. Although age does play a major role too. If the car has 100K+ miles on it, I would suggest a chain and tensioner and rails while you're at it. The original chain is of the endless type whereas a replacement obviously has a master link. Can you hear any slapping when you start it up after it's been stting for a while? If so, then definitely perform the above mentioned services. Good luck!



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Rgds,
Aaron Greenberg
MB technician
Mercedes-Benz of Cincinnati
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'86 420SEL
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'84 BMW 745i Turbo

[73MB280SEL]

Aaron,

Thanks for the FB. I really don't hear any slapping or strange noises when starting the engine cold. I had the driver's valve cover off this weekend for valve adjustment and re-examined it. Still looks pretty good, but as stated earlier, I didn't see any signs of a master link.

I polled a few friends and auto enthusiests and everyone agrees with you that it should probably be replaced even if just for peace of mind.

p.s. Got the valve clearance adjusted correctly (on the drivers side anyway) and the timing set properly. When these are adjusted properly, these cars really run well. Man, what a difference. Just hope the valves on the driver's side aren't burnt up or worn through the hard surface.

Sholin