Repairing VANOS M52TU questions

[AccordULEV]

Hi guys - been doing a ton of work on this 1999 528iT. Posting things in the Wagon forum doesn't seem to get much attention so I'm posting here.

Had car for 3 weeks, have replaced heater core coolant pipes and rear shocks and OFH gasket is next. This is the first time I've ever even been inside a BMW mind you, much less owned or popped the hood on one. I'm starting to really like how BMW does some things...electrical connectors and coolant connections way awesome!!

When I start car in mornings, I'd come back to find engine off. Knew it had a bizarre intermittent (q 10 seconds) stalling problem when cold. When chasing this problem down today, noticed the VANOS solenoid would make a click /trilling noise as this momentary idle problem was happening. Apparently that's the VANOS seals, as I have researched and found out. Got a repair kit on the way along with valve cover gasket seals.

From what I'm reading also, a malfunctioning VANOS will cause power loss in low and mid-range rpms. I guess that's good news because it already has phenomenal power throughout rpm range. More power is better.

Oddly, I've had no check engine light. And no DTC codes stored. The OBD-II scanner is reporting pretty high fuel trims though. Like LTFT at around 8-10% for both banks and 2-5% for STFT on both banks. I kept thinking I had a vacuum leak after removing the intake manifold to replace the CCV and those coolant pipes but now I'm sort of thinking the VANOS not operating correctly is causing the mixture to be off.

Is there anything else that needs attention while I have the VANOS off of the head?

Been watching YouTube University on the removal - other than not rotating the engine and knowing the camshaft bolts are reverse thread, any other advice?

If anyone has any inclination to answer questions about subframe bushings, I posted in the Wagon subforum a few days ago with no response so far.

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[Ed CT]

Check out the Beisan site for your dual VANOS R&R procedure.
http://www.beisansystems.com/procedures/

[Mike WW]

I never scanned mine when I had vanos problems, the 2000 528it that is, but no CEL. But symptoms were surging idle when cold, with occasional stalling, lousy gas mileage and a severe drop in midrange power. My MPG was down to 18-19 and went up to mid 20s after I did the seals. 25% seems crazy, but that's what it was.

X2 on the Beisan site and I would suggest buying parts from them too, not much more expensive and they're the ones who seemed to have figured it all out. Rebuilding the Vanos is really pretty straightforward, more intimidating than difficult and oddly easier on double vanos than single..

[ross1]

Follow the instructions at the Besian site. It's just a nuts and bolts job that requires some attention to detail.
Good time to do the OFH gasket and VANOS oil line too.

[effduration]

In addition to the Vanos re-build, I would pull the idle speed control valve, flush it with brake cleaner and shake it side to side to confirm it rattles. While you're there I would also pull the DISA valve and visually inspect it, making sure the flapper is still intact.