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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 11-03-2012, 11:21 AM   #1
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Join Date: Sep 2009
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My Ride: 330 CiC, 330i
Project M54 Engine: Vibration Damper removal and Crank locking pin test

Vibration damper removal and crankshaft locking pin test

Link to other parts of the project

Some may be interested in this. If so read on. It is in regard to using the crankshaft locking pin to hold the crankshaft while removing the vibration damper bolt at the front of the engine.

One of the most difficult tools I found to make when doing the project was the one to hold onto the vibration damper so I could remove the large bolt that holds it on. The one I made eventually broke apart due to the huge amount of torque being applied. There are many posts on this site that say it is ok to just put in the crank locking pin and hold it this way. The BMW TIS says not to do this. I always assumed that there was the chance of damaging the hole that the pin fits into, and then forever afterwards the pin would not accurately lock the crank at top dead centre.

I thought Iíd test whether or not it does damage it. Iím going back to Australia soon (I canít wait to get in my car again) and the export rules where I currently live wonít allow me to take the engine home. So I was prepared to sacrifice some components if it was going to give me some useful information.

Here are a couple of photos so you know what is going on.

Here is some maths so you know what forces are going on. If you are not interested in this, go to the bottom to find out my results. Iím not going to talk Newtons here (the unit of force) as there would be many who this wonít make sense to. Iíll convert also to a weight in kg so people have an understanding of what is going on.

The torque applied to the vibration damper bolt is 410Nm. This equates to a weight of 41.8 kg being applied at a distance of 1m. The locking pin needs to oppose this force, but as you can see it is only 115 mm from the centre of the crank. Therefore the force that is being applied to the end of the pin is 410/0.115 = 3565N or 364 kg.

This applies a torque to the pin. The distance from where the pin fits into the flywheel and where it pivots in the block is 45mm. So the torque being applied where the pin fits into the block is 3565 x 0.045 = 160Nm. This torque needs to be opposed by the hole in the block where the pin fits. This hole is 15mm deep. Therefore the force on each end of the hole is 160 / 0.015 = 10,695N or 1091 kg. Thatís right, the ends of the hole that hold the locking pin in place have a force of approx 1.1 tonne applied to them when you torque the vibration damper bolt.

The question is if this is enough to damage the hole. Only a practical test could find out.

I bolted the block down and then torqued/loosened the vibration damper bolt 6 times and measured if there was any deformation of the locking pin hole. I initially wanted to measure the hole before and after, but due to how the hole is reset inside the block, it wasnít possible to get any measuring tool I had in there to this. I ended up just taking before and after photos of the flywheel and comparing them.

Note that when you fit the pin, there is still just a slight amount of movement of the crankshaft back and forth that is available. This can easily be seen on the teeth on the flywheel and where they were in relation to a metal ruler sitting on the block. What I was attempting to measure was if this movement of the crank increased due to deformation of the hole after the torque was applied.

Here are the before and after photos. You will notice that they look slightly different, but the amount of movement that is available is identical. I enlarged the photos to high resolution and measured how much movement was available. The difference in what they look like is due to the pin bending. This happened progressively more and more as the experiment went on, so by the time that Iíd done it 6 times, the bend in the pin was approximately 0.5 mm over its length. Easily fixed by putting in a vice and tapping it back straight. However from what I could see, there was zero deformation of the hole.

I would be very happy using the locking pin to hold the crankshaft while removing the front bolt. I had said in my vibration damper post that I would not do this, however my mind has been changed. I wouldnít bother making or buying the tool that holds the vibration damper, and just use the locking pin to hold it instead.

I must point out here that the pin I used here is not an official BMW tool. I knew the dimensions of the tool, so I went to a local metal working shop and had them knock me one out for very little cost. It was just made of mild steel. Iím not sure what other tools available are made of or if they would fare any better.
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Old 03-11-2015, 08:59 PM   #2
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Join Date: Oct 2011
Location: Monterrey, Nuevo Leůn
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My Ride: 330i
Thanks for your explanation, but unfortunately i have the engine mounted, would somebody let me know how can i Tight the Damper bolt without dissamble the engine.

Best regards
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Old 08-22-2016, 11:00 AM   #3
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Bump for a super awesome post.
2003 BMW 330i ZHP
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Build thread: http://forum.e46fanatics.com/showthread.php?t=696662
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