damaged head bolts?

[tooheavy]

Hi, has anyone had any experience of damaged head bolts on a 124? Local garage could not remove the head to replace gasket, due to the bolts being damaged. They managed to get one out, and advised against drilling the others due to the time/cost involved.

 

[Ian B Walker]

Use a good quality spline shaft (M12) and lots of penetrating fluid. Take it slow, tighten then untighten a fraction at a time.

 

[tooheavy]

Thanks, excuse my ignorance but are the bolts worked on from the outside with something like a socket, or does the tool fit into them like a hex key ? Is that what a spline shaft is ?

 

[compress ignite]

it's a Twelve point (Industry slang name is "XZN")

Same concept as an Allen Wrench.
It fits into the ("Cleaned") head of the Bolt.

Picture courtesy GSXR:

 

[Druk]

Since these are 'one shot' stretch bolts and need renewed every time, maybe someone has used cheepo Eurocrap-parts bolts at some time in the past. These items are of inferior quality to OEM bolts. The splines are a slack fit.