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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 54028
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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I have a 68 280 sl were are the timing marks on the crank?

Customer Question

hi i have a 68 280 sl were are the timing marks on the crank?
Submitted: 2 years ago.
Category: Mercedes
Expert:  Marty replied 2 years ago.

Hi, are you trying to set the ignition timing?

Customer: replied 2 years ago.
no i replaced the head and trying to find tdc on the crank for the timing chain
Expert:  Marty replied 2 years ago.

Ok, is the head back on the car already? Are the rocker arms installed?

Customer: replied 2 years ago.
it is
Expert:  Marty replied 2 years ago.

Rocker arms off?

Customer: replied 2 years ago.
No it's not do I need them off
Expert:  Marty replied 2 years ago.

I'm just concerned that you might have bent the valves when you set the head on. Are the valves of #1 cylinder closed? Was the #1 piston up when you set the head on?

Customer: replied 2 years ago.
Well it wasn't bolted down yet and couldn't find the marks on the crank
Expert:  Marty replied 2 years ago.

I'm assuming that the crank pulley is still on the crankshaft. The marks are all the way in against the block on the innermost crank balancer. There are two sets of marks on the balancer. You use the ones that are closest to the motor. The pointer is on the right side upper at about the 1 o'clock position as you are facing the motor.

Customer: replied 2 years ago.
But if I have that on 0 #1 cyl is not tdc
Expert:  Marty replied 2 years ago.

You have to be careful that you don't run the valves into the pistons and bend the valves. When installing the head you should set the cam on the timing mark with the lobes of #1 cylinder pointing up. The #1 piston should be at TDC when installing the head. You can back the crank up about 20° just to be sure nothing hits when you set the head on then rotate the crank to TDC and install your chain.

Expert:  Marty replied 2 years ago.

Someone may have installed the balancer incorrectly. Can you easily remove the head and visually put the piston at TDC?

Expert:  Marty replied 2 years ago.

Do you see the two sets of marks on the crank pulley?

Customer: replied 2 years ago.
I set the most inner set of marks to zero
Customer: replied 2 years ago.
the head is off at this moment
Expert:  Marty replied 2 years ago.

Ok, when you put #1 piston at TDC you will need to make your own reference mark on the crank pulley.

Expert:  Marty replied 2 years ago.

Check the outer marks and see if they line up but most of the early SL's used the inner marks.