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Discussion Starter #1 (Edited)
I was wondering how many people have measured their VANOS gear backlash BEFORE they removed the VANOS pump. Just to be clear I measured mine with the main oil pump removed so there is no influence on the chain from the tensioner. I did this mainly to understand what the baseline was for the car which for which did not observe any excessive noise (due to insufficient or excessive backlash). Mine measured at just under 0.12 mm (looks to be 0.118mm) with my Mitituoyo. Yes, that is double the minimum spec (0.06mm) and well outside the max spec of 0.08mm

Just to put it out there, I have quite a bit of experience using test indicators, I know how to set zero and set the indicator tip in the correct orientation to measure backlash. I wish I had my other indicators on hand with me yesterday just to rule out whether the one I was using was out of calibration. My most fine indicator is a 0.0001" and I didn't bring it on purpose because I didn't want to count revolutions and convert to units. The 0.01mm per division is the right unit anyways. I have a rigid setup, using a flexible arm style arm with the base threaded in to one of the M8 oil pan bolt holes in the block.

I did a search and I couldn't find much commentary in any thread that talked about backlash values before removal, however I could be wrong since the search feature sucks.

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Although I didn't write down figures, I measured backlash before removal and found it within spec. Better loose than tight anyway.

Do you have more pics of how you set up the test indicator? Just curious...
 

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Discussion Starter #3 (Edited)
I made a mistake in typing in the value and have corrected it in the original post. The value shown is about 0.118 mm. I agree that over time the backlash is only going to get larger, but I figure that it is helpful for people to understand what their baseline is. I'll likely set mine to the top end of the spec 0.08 mm when I reinstall it later this month. Seems like 0.100 mm would still be fine. Frankly this backlash setting step was a bit confusing when I had first read it. In looking at the pump and how it is located, there are through hole dowels that provide a rough positional location if the pump mounted to the bottom of the block in the first place. Smacking the pump with a hammer will only move it so much. If I have time reinstalling, I may see what the min and max backlash range I can get. I removed both pumps and will tear them down to inspect. This is something that I can do inside.

I did not take pictures of the set up "in situ" but I have the VANOS pump and flexarm and indicator in my living room so I can take a picture later and upload.
 

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Discussion Starter #4
Here are some pictures of my flexarm and indicator setup. I kind of have this layed out in a way that resembles how the VANOS pump hangs down from the engine block. The indicator show is also my other one which is my Interapid (vs. the Mitutoyo which is what I actually used to measure backlash). They are both the same style with regards to the indicator needle axis being 90 deg to the back of the indicator face. The more common and cheaper indicators are where the indicator tip is on the same plane as the face. I have some of those too, but did not use them with this task. With an indicator style like that, you would need a longer arm, or position the base of the flexarm in a different hole, that would result in a less rigid setup. The 0.06-0.08 mm spec is actually quite large and many alternate setups would work just fine, I just grabbed what was optimal when I was prepping for the job, so this was what I had on hand.

The VANOS pump would typically be on the other side, etc. I had to lay it out this way so the indicator tip could be properly positioned, which is critical to measure gear backlash. Ideally the indicator tip points directly to the center point of the gear. The adapter shown in the 3rd picture is a M8 thread adapter which fits perfectly in the 20+ oil pan bolt holes. The base of the flexarm I guess is an M10 (I've not bothered to measure it). There are no holes in the block in that area that you could use to attach an M10 sized stud, otherwise I would have done so. When you twist the red arm it tensions and "locks" the arm in it's flexed orientation. The three other knobs are fine adjustment knobs to zero in the indicator in any of the 3 axes. This is the only why to PROPERLY zero the dial for a test indicator setup.

This is all stuff than any machinist would be familiar with and have on hand (with the exception of the M8 to M10 adapter base), it's all quite expensive and I wouldn't necessarily buy it for this job, but like most things, it does cost less than 1 new OE VANOS solenoid.


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Discussion Starter #5
Here is the set up mounted on the engine. Also in the prior message I incorrectly mentioned the size of the thread base of the adapter and base. The adapter allows it to fit M6 holes, so the base itself is M8.

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