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Old 28-03-2020, 02:24 PM
Howm58 Howm58 is offline
Join Date: Mar 2018
Posts: 43
Default Vanos Repair notes

Hi everybody,

I thought I would share my experience of doing a Vanos rebuild on my 1999 S50 as a winter project.
I used a Beisan seal kit (Hack Engineering) & followed a mixture of their instructions & TIS. JuhaV (on this forum) has written a very good article on this subject as well, I agree with him that some stages of the instructions are not very clear or helpful.
I found it fiddly, time consuming & a little frustrating at times but certainly not as difficult as some would suggest. If you are good with the tools and would take on a timing belt replacement on most modern engines without hesitation, then you should be able to complete a Vanos rebuild.
Disclaimer : I am not a qualified car technician, just a keen DIY mechanic with a lot of years experience.
As for following the instructions, when installing the intake cylinder in Vanos unit with new O ring I would suggest fitting the inboard cover (all seals removed) with just a couple of bolts (finger tight) to prevent pushing the cylinder all the way through & damaging the O ring (as I did!!). It should become obvious as you follow the process but the Beisan instructions omit this.
I did the full rebuild on my car, including the S62 diaphragm springs. I chose to take the exhaust camshaft completely out of the car. Less chance of losing a bolt down into the engine (they are stainless so you won’t even be able to fish them out with a magnet!). Looks scary at the time but if you are methodical its not that bad.
The TIS instructions are better when finally fitting the rebuilt Vanos unit to the engine. With both camshafts locked in the correct positions I left my helical gear sets separate from the Vanos unit and offered them up to the camshaft hubs independently. If the helical gears don’t slide straight in DO NOT rotate the hub to line them up, simply draw the gear set out completely and rotate to the next straight spline that goes directly into the camshaft. Eventually you will a position where the helical splines slide straight in, when you find it mark the hub and a helical gear tooth with a marker pen. Then bolt up the gear sets to the Vanos unit & refit the whole unit, lining up the marks as you go. Make sure oil pump lugs line up before you push the unit home (VERY IMPORTANT).
On a slightly different subject, I have spent nearly a year trying to find a fairly substantial engine oil leak, to the point of buying a sump gasket (that’s a BIG job). As the leak seemed to come from the passenger side I decided to replace the oil filter housing gasket (heard that they can leak quite badly). When I finally got to it there was slight weeping & the 21 year old gasket felt like hard plastic instead of rubber (worth doing) but it certainly wasn’t leaking substantially. Whilst putting everything back the workshop manual suggested replacing the dipstick tube O ring, What O ring? There are two metal rings (that I had mistaken for O rings) on the tube to stop it dropping too far into the sump when refitting. I found a tiny remnant of what once might have been an O ring in the sump hole. The new O ring is quite a tight fit when reassembling & guess what, NO leaks since. About £2 & 10 minutes work could have saved an awful lot of searching!! Check this out before doing anything else if you have an oil leak coming from the passenger (left) side of the engine.

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Old 28-03-2020, 02:47 PM
Dave P's Avatar
Dave P Dave P is offline
Join Date: Dec 2008
Location: Cheshire
Posts: 27,217

Well done for doing the vanos yourself and taking the time to post up details, I am about to change my dipstick tube and was wondering about the o ring but will start up a new thread.
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Old 22-05-2020, 12:04 PM
Rags Rags is offline
Senior Member
Join Date: May 2006
Posts: 2,775

Great work and advice on the dip stick oring!
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