Subject: VANOS repair Bucks UK Author: fastnfurryous : member since June, 2008 : 1 post Posted on: 2008-07-05 14:49:28

5 spd manual e46 touring 328i, 74k miles, trampoline idle when cold...

Did my VANOS piston seals today along with a big service, filters, oil and suchlike. It's warm here at the moment so my engine has not been doing the bouncing idle thing that it does in the winter, but the engine did tend to bog down at low revs and there was a noticeable step up in torque as the revs went through 3k rpm.

Job was a good 'un - great how-to as other have said. If I had only been doing the seals it would have taken me probably 4 hrs, I have all the tools and garage etc so pretty well set up for doing this stuff. Having said that there was nothing particularly specialized needed.

A couple of observations: I removed the old PTFE and nitrile rubber o-rings from the pistons by clamping the pistons in a vise (I have soft jaws on mine, don't do this with steel jaws, you _will_ mar the piston faces!) and used a Stanley knife (Exacto in the US I believe) to cut through the seals at a shallow angle - this worked well but I went really carefully. Old seals and O-rings very stiff, pistons were flopping around in bores on disassembly.

I spend quite a while bedding in the new seals manually before re-assembling the VANOS unit with lots of new fully-synthetic oil applied lots of times during the process. When I re-assembled the VANOS unit to the cylinder head, I had a RH click torque wrench as described in previous post; I judged the torque required by the pressure on a RH threaded bolt just before I torqued the VANOS piston bolts. This worked pretty well for me, no breakages or problems.

Put all of the stuff back together and fired it up. No worrying reports from the OBC, _immediate_ stable idle, no rattle from the VANOS unit anymore. Took it for a quick run around the country lanes; maybe I am "wanting" it t be different but it feels better - no dip in te revs when I bring the clutch up anymore, very stable idle. The time I used to notice the lows revs torque deficit most was when reversing up my inclined drive when I would often stall the engine when "creeping". No longer! Also the step at 3000 is gone, just smooth power all the way through.

Altogether 5 stars so far, will report back after 500+ miles, bur so far, well done Rajaie, nice alternative to the Main Stealer solution!

FNF

• VANOS repair Bucks UK - fastnfurryous 2008-07-05 14:49:28 (492 views)
  • Thanks! Please also report after seals break-in period (nt) - Rajaie 2008-07-06 16:06:18 (350 views)