I am looking for cylinder head bolt tightening torque specs for a Benz OM651

Had this issue many years ago for an old engine.

The mechanic and I took the bolts and worked out the max allowable loading then took 2/3 of that value.

We also looked at the threads and the material of the head and block then derated that calculated by another 10 or 15%.

The engine ran fine.

Do also consider the head gasket as part of the process - for us is was a copper gasket.

According to this forum thread, the torque values for the OM651 engine head bolts are as follows:

• 1st pass - 15Nm (11 lb-ft)
• 2nd pass - 90°
• 3rd pass - 90°

I'm assuming these bolts are most likely torque to yield bolts, you need to be using new bolts when you do this.