[command_liner]

Does anybody know the crank pulley bolt pattern? If so, can you provide the specifics?

The front pulley/harmonic balancer uses a small, probably metric, bolt pattern, but I have not been able to find the specific size.

Why do I need this?
It would be easy to make a crank turn adapter/socket to fit this pattern, and cost 1/4 as much as the BMW tool. I wonder if it is worth making a production run of such things.

If BavAuto can make money selling walnut blast kits, I could make a few bucks selling the adapters required to turn the engine over.

[BB_cuda]

There is a guy named bodacious on other forum that has 2 M57 engines. It's likely he could take measurements for you. But you will need to be patient. He is a busy man.

Are you trying to grab central bolt head or what? Not trying to scam you, trying to understand what you're after. Wouldn't it be damn hard to turn over an engine that is 16.5:1 CR and no spark plugs to pull?

[command_liner]

Originally Posted by BB_cuda

There is a guy named bodacious on other forum that has 2 M57 engines. It's likely he could take measurements for you. But you will need to be patient. He is a busy man.

Are you trying to grab central bolt head or what? Not trying to scam you, trying to understand what you're after. Wouldn't it be damn hard to turn over an engine that is 16.5:1 CR and no spark plugs to pull?

The M57 uses 4 torx head bolts in a square pattern to bolt the harmonic balancer onto the crank. There is no one large bolt.

BMW makes a special tool, which you can buy for $87, which slides over the heads of these bolts and lets you turn the engine over. Doing my CBU removal work, I am using a field expedient tool to turn the crank: it is not hard to do by hand.

I have a friend that does a lot of work with custom aluminum extrusions. It would be easy to make an extruded aluminum piece that
1) fit over the four bolts
2) accepted a 1/2" ratchet
3) fit in a 36mm (or so) 12 point socket

It should be possible to produce these for sale in the $20 range, way less than the BMW cost. I would have to sell a few hundred to make any money, but it might be worthwhile.

Another possibility is to have a similar flat key water jet cut out of 3/16" stainless plate. Plasma cutting from steel would work, but would need deburring and coating.

In general you want to be careful working in this area because you do not want to screw up the bolts that hold the balancer onto the crank.

[BB_cuda]

Sounds like you just need the bolt circle diameter and the close fitting diameter to capture each torx fastener's OD. I guess no way to do a direct measure on your's?

[cincy_335d]

Can you provide a link or part number for the Bmw part you are referring too? The part that fits on the crankshaft vibration balancer to allow for it to be turned.

[Hoooper]

Originally Posted by BB_cuda

Wouldn't it be damn hard to turn over an engine that is 16.5:1 CR and no spark plugs to pull?

Not as hard as you might think. If you can properly torque a wheel bolt you should be able to turn the engine over.

[cincy_335d]

I am working on the ac belt squeal currently. Was able to get a 7mm socket on the ac pulley and get the crank to turn. It surprises me that it requires a Bmw specific took to turn the crank "officially". I was able to get my local dealer to quote a price for the tool. 243 dollars...