Chain Stretch on 81 240D - Page 2 - PeachParts Mercedes-Benz Forum

whunter · #16 06-25-2010, 02:25 PM

Quote:

Originally Posted by treiberg

Thanks for the email whunter!!

I am moving forward with my theory that somehow the timing pointer is bent. If I can imagine it bent back so the edge is square, that would put timing back very close to zero degrees, which is a huge relief. I think the little post on the balancer actually pushed that pointer back, like there wasn't enough clearance and it just grabbed it and bent it back. But to get an accurate timing mark, I need to either fix the bent peice or make my own mark. Knowing where TDC looks pretty involved from the FSM. So I am hoping that timing indicator can be replaced. It looks like it is just bolted on...can anyone confirm that? Or maybe I can just unbolt it and bend it back. (see pic)

it is bolted on..

treiberg · #17 06-25-2010, 02:52 PM

Quote:

Originally Posted by whunter

it is bolted on..

That is great. So I think I will unbolt that pointer and see if I can bend it back, before I go hunt down another one. As long as the pointer comes out at 90 degrees from the edge of the bracket, I should be able to get it very close to original position. Then we can begin to assess chain stretch.

If chain stretch is less than 4%, then it is still a good idea to inspect the rails and tensioner, correct? What do you look for to know if they need to be replaced? Or should they just be replaced on a mileage basis? The problem is, we as 3rd+ owners of these cars, don't always know history and true mileage.

If chain strech looks minimal, then I also need to proceed with IP timing. I have got to try to solve this annoying vibration at idle!

leathermang · #18 06-25-2010, 03:16 PM

Most of the time a calamity happens in these old cars which involves the chain... it is not the actual chain which gave way... it is something in contact with the chain.. ...
so it is really prudent to replace those items in contact with the chain if there is any doubt... many times people will just replace the chain... ( like previous owners ) and you wind up with stuff which is past being safe even though you have little wear indicator on the chain itself....

treiberg · #19 06-25-2010, 04:55 PM

leathermang, I see you have an 80 240D, which should be pretty close to mine. Could you possibly take a glance at your timing pointer and compare to my pics here? I would really appreciate it, as this would help me confirm that it is just bent.

treiberg · #20 06-26-2010, 01:40 AM

Yep, that was it. The pointer on the bracket was bent back, and causing about 22 degrees of error in the reading! The picture shows how it is supposed to look. I just took that big bolt off, bent the prong back, and reinstalled it. I can see now that somehow that pin on the balancer got too close and hooked the pointer. I am guessing that bracket was mounted improperly or someone turned engine over before it was fastened or something.

And the good news, the timing chain stretch appears to be very minimal showing about 2-3 degrees of stretch (I know, I know, not the official 2mm list method, but close enough for me for right now). Tensioner and rails should probably be replaced someday, since I have no idea if these are original. I think this engine only has about 100K on it.

Now, about the only thing left in my search for a vibration fix is injection timing. That will be my next pursuit.

leathermang · #21 06-26-2010, 09:44 PM

I just saw this and it seems you are fixed..but if you still need it I will take a picture...in the morning...