cylinder head replaced on e300 td

[Archie 2]

I have just renewed cylider head gasket after head being skimmed.
Will I need to re- adjust / re- tighten all bolts etc after a given mileage ?
Thanks.

 

[BlackC55]

nope.

The only time it needs tightening is when the bolts are installed.

 

[Archie 2]

Thanks for your quick reply.I must be showing my age ! On previous cars I have owned ( like Fords and such ) they always said that you had to re- tighten head bolts after so many miles !Times have changed eh ?

 

[wireman]

It is not the times that change but the techniques.
In days of yore we would torque the head down, this gave an aproximate crushing pressure to the head gasket, regardless of its thickness.

Today we torque until the air space is gone and then stage tighten to a specified bolt insertion depth, usually by further equal rotation of each bolt in several stages say 60deg a go. The bolts stretch to control the pressure applied to the gasket, in some engines new bolts are required if they are disturbed.

This stage tightening method gives a better and more controled fit of the gasket faces to the head and block, resulting in more reliability.

 

[C240yaz]

Thanks for your quick reply.I must be showing my age ! On previous cars I have owned ( like Fords and such ) they always said that you had to re- tighten head bolts after so many miles !Times have changed eh ?

In days of old, I and others always believed this retightening instruction to be a "myth", we never done it, and it never came back and bit us once for not doing it.

 

[Bolide]

It is not the times that change but the techniques.
In days of yore we would torque the head down, this gave an aproximate crushing pressure to the head gasket, regardless of its thickness.

Today we torque until the air space is gone and then stage tighten to a specified bolt insertion depth, usually by further equal rotation of each bolt in several stages say 60deg a go. The bolts stretch to control the pressure applied to the gasket, in some engines new bolts are required if they are disturbed.

This stage tightening method gives a better and more controled fit of the gasket faces to the head and block, resulting in more reliability.

This assumes, of course, that you used new bolts. You did - didn't you?

Nick Froome
www.w124.co.uk