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E34 M50 Idle Control Valve Replacement

Brett Anderson, a Master Mechanic on BMW's had this article on the web.  I
tried going to it today but the web pages were gone. Luckily, I had a hard
copy so I scanned it in.  I had the opportunity to use his procedure today
and it worked great.  What was estimated to be a 2 hour job at the
dealership took me under an hour.

You might want to save this email for posterity, especially if you own a
car with the M50 engine.


- ------------------------

Idle valve replacement M50

Replacing the idle valve on an M50 is a very difficult job, not
complicated, but awkward.

First, remove the airbox by loosening the hose clamp on the bellows, and
loosening the two 10 mm nuts holding it to the inner fender, no need to
remove the nuts, just loosen them. if you have cruise control, lift the
cruise actuator off of the studs and then lift the airbox up , remove the
10 mm bolt holding the sensor into the rear of the airbox and unplug the
Air Flow Meter. Lift the airbox up and out of the car.

Remove the hose clamp from the other end of the bellows, pull the bellows
off of the throttle housing and pull the idle hose out from the bellows.
Unplug the Throttle Position Sensor, gently remove the ASC cable from the
throttle housing, if you have it and remove the 4 10 mm bolts holding the
housing onto the intake manifold. There is no need to remove the throttle
cables, just move the housing out of the way.

Next, remove the cap from the oil filter housing, and remove the oil
filter. Cover the housing with a clean rag to prevent foreign material
entering. You can now reach in under the manifold from the front with one
hand and the side with the other. You will need to watch through the small
holes in the top of the manifold to see what you are doing.

In the hole left by the throttle housing, you will see the outlet pipe of
the idle valve. This fitting is clipped into the manifold with a very
fragile plastic clip. A smart move would be to buy a new fitting when you
get the idle valve, it only costs a couple of dollars and makes a lot of
sense to replace it at the same time. You can unclip the fitting through
the hole in the manifold and pull it away from its
mount Pull the other end of this hose off the idle control valve. Now push
the valve toward the firewall until it comes out from the rubber bracket
that secures it. It is best not to remove this rubber loop from its mount
as it can be very awkward to put it back in. Now that you have the valve
loose, you can raise it to gain access to the inlet hose. If there is no
clamp on it, you can remove it there and then, if it has a hose clamp on
it, you may find it easier to remove the valve and hose together. The hose
is the same one you removed from the intake bellows earlier, you can feed
it through, under the manifold , as you pull the valve out over the oil
filter housing.

When installing the new valve, take great care to get the hoses on all the
way, if the intake hose goes on easily, put a clamp on it. Make especially
sure the outlet pipe is correctly attached to the valve, and it's fitting
is properly seated in the manifold. A new fitting comes with a new 0 ring
already fitted, you will hear it snap into place when it is located
correctly. If this hose comes off, it will cause stalling at idle, even
backfiring, and a very rough running engine.

Feed the inlet house back through under the manifold until the valve is
back in place, push it back into the rubber loop , and then put the outlet
hose onto the valve. The outlet hose is not very pliable so it is best not
to try and force the entire assembly under the manifold. Put it on last.
Don't forget to plug the electrical connector back in, don't laugh, its
been done.

 Norm Grills   				BMW CCA # 57310
 Plano Texas   BMW's  - 635, 525		BMW MOA # 19040
                          K1100/LT			IBA member

   	Lone Star Chapter BMW CCA

        	Lone Star BMW Riders   	<http://web2.airmail.net/grills/>
 	E24 FAQ