M103 engine, Cylinder head bolt retorque

[dpkreuze]

As we 300E/190 2.6 owners probably all know, the head gaskets leak.
Has anyone heard of restretching the head bolts to cure the leak?
I know we retorqued a lot of heads on the old V8's, however for different reasons.
Thank you my friends,





Thanks for the info.
I loosened each head bolt, retorque it to 55nm, stretched it 90 degrees in the proper sequence. Then I turned the final 90 degrees rotational torque (stretch) on all of the bolts in sequence.
This head gasket only leaked externally before. So far it has not leaked and if anyone is interested I wil post a progress report after the car has been driven.

[Strider]

Originally Posted by dpkreuze

As we 300E/190 2.6 owners probably all know, the head gaskets leak.
Has anyone heard of restretching the head bolts to cure the leak?
I know we retorqued a lot of heads on the old V8's, however for different reasons.
Thank you my friends,

You head gasket is leaking oil into the coolant yes? (This is the most common type of head gasket leak... High pressure oil passage just milimeters away from a lower pressure coolant passage, and only a thin gasket seperating them... Design specification flaw for the original head gasket material. The only cure is the replace the gasket, and the new gaskets are made of better material.

As for the head bolts. They are 'torque to yield' bolts, and since they have been stretched beyond their yield point already, you really won't achieve any more clamping force by torquing them more. You only run the greater risk of striping the threads out and doing real damage.

In fact, you are NOT to re-use the old head bolts after you replace the head gasket. You have to get new head bolts, so they can be torqued to yield.

[t walgamuth]

actually they can be measured and reused if they pass muster, i believe.

tom w

[autozen]

I support Strider's advice until you get to the reuse of the headbolts. Then I support Tom's answer. They can be measured and possibly be reused. When you find out how much those little puppies cost, you'll want to reuse them if possible.

[t walgamuth]

true dat

tom w