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Discussion Starter #1 (Edited)
I'm rebuilding a Vanos pump and wanted to throw this out there. In the process of doing failure analysis I've discovered wear in the race/ring of the Vanos pump. This part is not available and there are no options but to take risk and buy a "used" pump or spend $$$$ and buy a multi thousand dollar new pump.

I'm re-engineering this race and having a few machined & ground out of hardened Chromium steel bearing material.

Is there any interest here with a bulk buy? This part "refreshes" an old or used pump with a good needle bearing and good hub with pistons.

If there's interest.....I"ll take orders and have additional parts produced. Let me know....I have a little machining $$ in this and would like to recoup my NRE.

 

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Nice work Rick. Have you sourced the needle bearing yet? I've had a hard time removing them without damaging the housing, even after baking at 250 for a couple of hours to expand the aluminum housing.

Also, a point for anyone who has had damage to one of these, the shaft the rotor rides on can be cocked at an angle, make sure it's perfectly perpendicular to the housing.
 

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Discussion Starter #4 (Edited)
No source for the needle bearing. I have some ideas....but, nothing is just a drop in and requires grinding to finish. This needle bearing is in great shape. Each needle spins freely and the cage rotates with no binding.

Btw....the pre-filter to this pump was spot clean. Not a speak of metal or debris....so I'm fairly confident that contaminants from the oil did not cause this wear failure mode.
 

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I suspect weak springs in the pistons. The weak springs will cause the Pistons not to sit properly on the race -causing it to loose constant contact with the race which will cause the marks on it


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Discussion Starter #7 (Edited)
If there is enough interest I will put an order in to make (12). I purchased enough stock for (12). The cost is $295 each. Believe it or not machinist are expensive and there was several hours of shop time for these.

....and for that you'll replace the major wear item in the Vanos pump and be in good shape for another +50,000 miles.
 

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Discussion Starter #9 (Edited)
Looks good. I still believe the springs are the issue not the race.


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Thanks...but, the springs, or lack of spring pressure, do not create the wear load on this part. The compression stroke on each revolution creates +1,500 psi on the pistons on the load side. This 1,500 psi load is transmitted to the load side of the rotating hub thru the pistons (on that side) to the race bearing to the needle bearing to the pump casting. The springs are there to "return" the piston to the home position and draw in oil for the next stroke....And contribute very little load when compared with the pressure stroke on the opposite side of the rotating hub.

It's this +1,500 psi piston pressure that keeps the pistons radially engaged in the bearing race.

Wear over time creates discontinuities (a widening can be seen in the pic below) in the track/grove in the bearing race. Once enough material is worn away the race stops rotating in the needle bearing (causing the race to accumulate wear in one region) and the race fractures (a bump in the race) at the thin location....causing the famous Vanos "tick"...and can be heard and felt in the "Tee" oil line above the water pump at the top of the engine. Secondary fractures occur and chunks of this race material, when failing, can either take out the sprocket and main oil pump drive chain assembly and/or wipe the helix drive gears attached to the crank shaft (driving the Vanos pump/sprocket assembly). Failing race material also creates a side load to the pistons and creates scoring to the piston cylinder....causing the pistons to bind and not return and not pump oil. In either case Vanos oil pressure is either reduced or lost causing a warning to display and the car to go into limp mode.

Note that the pre-filter in my engine (Vanos pump intake filter) was removed from the engine and inspected. No debris was observed in this 100 micron filter (even with larger glitter debris in the main oil filter). This filter was never removed after the original pump failed. So, both pumps failed with "clean" intake oil. I don't believe dirty oil affects this failure mode as some believed.
 

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help me find a place that will do cylindrical grinding on Chromium Steel for less and I'm all ears....
I wish I could, but I don't know anything about machining, nor am I business oriented enough to find people in china to do it.

I'm ready to buy at a better price though :)
 

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Discussion Starter #14
Just started the car.....and everything is running smooth as budda. Vanos pumped right up with no ticks or bumps. I'll report back in a few 1,000 miles. We did several oil flushes and plan to do a filter change in a 1,000 miles....looking for a clean report. After that I'll list the bearing race parts.
 
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