Injector seals again boooooooooo

[Cole@MBS]

That's what WIS says, i guess there has been some clamps that have failed on the past, so mb are just being careful!

 

[kebo57]

HI there!
I got some photos here for everyone. It's from my ML270 CDI prob started from oil leaks after replacing the copper washer now thread from cylinder head that holds the stud bolt can't. Damaged thread of cyclinder head probably the cause. Anyone can give suggestion? Helicoil? glue will not be good i've tried it.

Hi your explanation is a not good
Is you stud bolt stripped / turning round & round with out getting tight
if so then you can Helicoil to recover the thread back to take the existing bolt, our re-tap the hole to take a larger bolt 8mm would be you next size up the open the hole in the clamp to take the 8mm bolt. where are you located

Kevin

 

[Rappey69]

I would stay well clear of enlarging the hole in the clamp as am sure it will then break in service.

 

[Number_Cruncher]

Yes, the best repair os to carefully drill out (don't go any deeper than standard), and fit a helicoil thread repair.

This is how the joint should have been made, by design, from the factory, as the hard wire of the helicoil insert makes a much better interface to the hard metal of the bolt than the soft aluminium of the cylinder head. The load is then transferred to the cylinder head at a larger radius, further reducing the possibility of any shear stress failures. Further to this, the slight movement between coils of the thread insert as load is taken up allows far better load sharing between all the engaged threads, reducing the peak load being transferred. (In a standard bolted joint, a rough assumption is that all the load is borne by the first few threads, with a wire thread insert, the load is much better distributed)

Apart from the warning about not drilling further than standard (there's a water passage below), the only other thing that must be right is that the helicoil must be drilled absolutely straight - any angle will impose bending loads on the bolt which it wasn't designed for.

In a previous job, I worked on the design and analysis of aircraft hydraulic parts - when we used aluminium, it was standard practice to helicoil, and screwing into bare aluminium was forbidden practice. Properly installed, helicoils are not a bodge or rough repair - in the case of this joint, I would say they represent a serious improvement over the standard (rather poor) specification.

.

 

[muller1]

Helicoils

In a previous job, I worked on the design and analysis of aircraft hydraulic parts - when we used aluminium, it was standard practice to helicoil, and screwing into bare aluminium was forbidden practice. Properly installed, helicoils are not a bodge or rough repair - in the case of this joint, I would say they represent a serious improvement over the standard (rather poor) specification.

.

I agree 100%, helicoils are used for repair work BUT, are fitted as standard in many applications where aluminium is used or the fasteners are removed and fitted on a regular basis, as they are a spring grade stainless steel, and are used a lot where salt or corrosion is involved.
MB should have done the job correctly to begin with and used Helicoils.

Mike