Camshaft sproket bolts stripped
 

Hello,
Today I was working on re sealing the upper timing cover when I discovered that all 3 sprocket bolts were stripped and just hanging.
How would you go about fixing this?
Replace the camshaft, try to tap and use inserts?
Does the sprocket holder comes apart from the front of the camshaft?
It look like the bolts used were of a smaller size than the correct ones, they were all the way in, the car was running fine, and it looks like it was for a long time.
Thanks for your time, help and advice
Ed.

1990 300SEL

Im confused by what looks like wooden shims in the 2nd picture.

The gear should come off fairly straight forward after you remove the timing chain tensioner to give some slack. Chain stretch, Did you check for that yet? line the cam marks up and look at the pulley to see how much.

There is suppose to be a pin coming straight off the end of the cam that keeps the gear lined up.
https://nemigaparts.com/cat_spares/epc/mercedes/1/m/103981/14k/05/015/?chasis=126025570

PS mods will soon move to W126 section for you.

I think I would remove camshaft, tap for next size

Thread insert (Timesert) would be my first choice. Second would be drill and tap the camshaft to the next size. You may have to drill the gear also.

It is critical that the pin previously mentioned be in place.

Good luck!!!

Hello, the shims were in place to be able to get the upper timing cover without taking the whole valve cover out. The gear is out.
I couldn't find the w126 forum, I will try to move it.
Thanks for your reply!
Ed

Thanks for your reply, Sugar Bear. I did not know of Time sert, brilliant system, I will see if I can find the kit and insert for that size bolt, if not I will do the second. Thanks again! Ed.

I did not see that pin, I will look again tomorrow see if it stayed in the cam.

Thanks, Tony, I will do that if I cannot find the right insert. I will try not to remove the cam.

Pack the timing chain cavity with clean rags, then invest time in sealing off everything you can where metal chips could enter. Consider laying a plastic cover over the top of the engine/valve train then slice a hole to open up only the area where you are working.

If you haven't done so, read up on and understand the M103 engine timing chain tensioner as it is only ratchets in the tightening direction. It will have to be disassembled and then reassembled to reset it, failing to reset it will leave the tensioner too tight causing damage to the chain and gears. It isn't complicated just difficult to get the large nut restarted against the spring tension. Eat a ton of Wheaties before working on that nut/spring tension.

Good luck!!!

Will do, Sugar Bear, I am reading about it.
Thanks for your time and help.
Ed

Hello,
Do you know if I remove the sprocket from the chain (I have it zip tied to the chain) and let the chain fall to one side will it disengage from the crank?
Thanks
Ed

I think the chain will fall off the gear if it drops down. Maybe you can turn the engine to TDC on cylinder#1 so if you lose the chain you can put it back with the cam in the proper position.

Yes that is good advice, if it isn't too late put the engine at Top Dead Center on the compression stroke. #1 piston @ TDC, cam lobes on #1 should be at the base circle/no lift point on the camshaft #6 lobes should be teetering, ready to open a valve at any movement. Only rotate the engine CW while facing the front of the engine. Tie wrap the chain or do something to prevent it from falling and getting jammed...been there.

Good luck!!

Thank you for all your time and help.
I will probably put the sprocket back and put it at TDC.
Do you know if the 3 bolts are M6 or M7s?
I measured a stripped one at 6.37mm
Thank you again.
Ed