Broken Vanos Mounting Bolt

[George Hill]

Crazy not to put the dowel back in.

Vanos being on is not just to allow a straight drilled hole, but to properly locate that hole as well.

Had to do this to fix one properly in the past

[E11even]

Ended up placing a helicoil in to ensure best bolt grab. Didn’t like drilling out that much metal for a timesert (yet).

reinstalled without a dowel on the exhaust side. Not about the cost, just the time to ship and needed to get it reassembled. May end up costing me more time, we’ll see.

The alignment of the Vanos looked good visually hopefully that means a good seal with the gasket. Bolt was able to be torqued to spec. Finishing a coolant flush then gonna start it up, and pray no oil leak there.

[E11even]

I agree and I didn’t feel good about it.

wish a had a pro that lived close. Nearest BMW mechanic is 4 hours away.

Crazy not to put the dowel back in.

Vanos being on is not just to allow a straight drilled hole, but to properly locate that hole as well.

Had to do this to fix one properly in the past

[E11even]

Everything reassembled and new coolant in.

Drove it last night about 20 miles, ran great after initial start up. No temp issues and no leaks I can see.

Sounds a little smoother than before but my VANOS was in great shape. Besides the chain guide looking thin and the oil pump disk with pretty significant tab wear everything looked good.

Appreciate all the advice. I’m sure I’ll need more in the future.

[sapote]

reinstalled without a dowel on the exhaust side. Not about the cost, just the time to ship and needed to get it reassembled. May end up costing me more time, we’ll see.

Since it still has one dowel sleeve, then you just need to align the vanos top surface to the head using a straight edge.
When I have the vanos pump disk redrilled with smaller holes with tighter clearance, I rotated the cam (by crank pulley) to center the disk to the EX hub while tightening the vanos bolts to avoid the pump disk off center to the driving tangs. This is more important than the vanos top aligned with the head but I'm sure the twos are related to each other.

[Stilt]

No reason it should have full threads but it's doesn't matter.
You're lucky it didn't strip the threads in the head. The remain broken bolt protruding or inside the threaded hole? If it's slightly protruding, then cut a slot on its end, then use the impact driver and hammer to turn it CCW back out just like a screw.

😅😅😩 I have a similar issue but my threads are stripped in the head, but not a stuck bolt. Need to fix soon, been putting it off for too long 😅.


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[Stilt]

Well, the dowel also helps align the surfaces on the head and vanos so that the valve cover gasket seals correctly. Personally, I would (and did) put it back on after a thread repair.

OP, I'd do what George Hill said. Timesert is doable without removing anything, you just need a right angle drill or to do it by hand. They also sell drill guides if you don't want to be taking the vanos on and off a bunch. Dowel will need to be trimmed slightly lengthwise, but that's about it.

I have a similar issue but rather my threads are stripped.

Are you saying that I could do a timesert without removing the vanos unit, and tapping directly through the unit itself and into the block. However, if I did that, would it mess up the dowel?

[sapote]

I have a similar issue but rather my threads are stripped.

Are you saying that I could do a timesert without removing the vanos unit, and tapping directly through the unit itself and into the block. However, if I did that, would it mess up the dowel?

The Timesert must be larger than the dowel which must be removed.

[E11even]

I thought everything was good but I have developed an oil leak at the Vanos gasket and bottom left bolt, which is probably just tracking down from a less than ideal seal from the top left repair.

I have everything pulled back apart. TimeSerts and Big Serts orders, new dowels, bolts and new gasket coming.

When using the timesert, did you countersink it using the tool or just leave it proud in the dowel hole and trim the dowel?

Also, would you put any extra 3bond seal in this area or around the gasket? Or just rely in the gasket?

[George Hill]

When using the timesert, did you countersink it using the tool or just leave it proud in the dowel hole and trim the dowel?

Double check yours but you should be able to have enough room to NOT countersink the timesert and still fit the dowel.

Also, would you put any extra 3bond seal in this area or around the gasket? Or just rely in the gasket?

I put gaskets on dry.

[E11even]

Double check yours but you should be able to have enough room to NOT countersink the timesert and still fit the dowel.




I put gaskets on dry.

Thanks. I’ll do trial fitment with the dowel in place.

[sapote]

When using the timesert, did you countersink it using the tool or just leave it proud in the dowel hole and trim the dowel?

The Vanos dowel hole should be uniform and no step I think, so a little protruding more dowel is a no issue.
Or maybe it has a step then check with a caliper.

[sapote]

But why it’s broken - having a too strong arm?
It really ruined the fun.