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Andrew
07-28-2007, 01:12 PM
Hey Guys

Recently, I have been getting strong vibrations in my steering column when turning the wheel AT IDLE. Furthermore, I can feel an almost "percolating" feeling in the brake pedal at stop lights for the first 10-15 minutes of driving. (I don't know if this is at all related.)

So, the first thing I checked was the power steering fluid. The level was fine, but I noticed that the previous owner put ATF oil in the system instead of the Pentosin CHF 11S fluid. I have searched the archives and saw that the recommended "fix" was to slowly siphon the reservoir and replace the ATF with the CHF 11S fluid.

I did this once yesterday and thought I noticed a reduction in the "vibrations" at idle. I did it again this morning (as the fluid was still very red), but the PS pump started groaning and the vibrations were shaking the entire car (even without turning the wheel). I eased the car around the street several times and eventually the vibrations and groaning went away. The fluid is again very RED as the CHF 11S mixed with the remaining ATF.

My first question is if all '95 540i's use CHF 11S, since the pump did not seem to like its first exposure to it. My second question is if you think I did any damage to the pump by waiting so long to change the fluid (about 6 months!)(When the car has been driven about 10 miles, the steering works perfectly.)

Luckily, I don’t see any major leaks in the hoses like a lot of 540is have (knock on wood!)

The car is a '95 540i 6Speed.

As always, thanks your input.
Andrew

Tiger
07-28-2007, 02:32 PM
If you have one of those oil vacuum tank... the thing that sucks up oil via dipstick, then I'd disconnect the hose and just suck everything up through there.

As far as damage? I can't really tell you...

Ross
07-28-2007, 02:39 PM
Get ALL of the ATF out of there. It will take quite a bit of uber costly pentosin but is far less than resealing your entire hydro system.
All the noise and such you experienced are probably air being purged from the system. Cross your fingers.
Hopefully, one day the PO that put ATF in will receive the beating he so richly deserves.

Andrew
07-28-2007, 02:52 PM
Thanks guys. Yes, I do hope he (or his mechanic) receives that beating!

I don't see how you can completely ignore that big green sticker that reads "CHF 11S." Interestingly, the text engraved into the cap under the sticker says "ATF Oil Only" so I started questioning if all 540is really used CHF 11S. ATF gave me no problems for several months... I suppose I should have looked earlier.

Buying an oil pump as Tiger suggested is probably going to be cheaper than flushing $25.00 liters of Pentosin through the system!

I'll let you know how it turns out.

Andrew

yaofeng
07-28-2007, 07:11 PM
You can open a drain plug in the bottom of the pump to drain fluid. The green label on mine got lost during the conversion. Under the label it says to use ATF. I think BMW is getting sloppy just putting an adhesive based label on the car.

632 Regal
07-28-2007, 08:47 PM
i wonder if your car has the "brake bomb" I had that in the E31 and it was fubared, replacek it and the brekes stopped pulsing



Thanks guys. Yes, I do hope he (or his mechanic) receives that beating!

I don't see how you can completely ignore that big green sticker that reads "CHF 11S." Interestingly, the text engraved into the cap under the sticker says "ATF Oil Only" so I started questioning if all 540is really used CHF 11S. ATF gave me no problems for several months... I suppose I should have looked earlier.

Buying an oil pump as Tiger suggested is probably going to be cheaper than flushing $25.00 liters of Pentosin through the system!

I'll let you know how it turns out.

Andrew

Andrew
07-28-2007, 10:11 PM
Hi Jeff

It's interesting you mentioned the "brake bomb." The first post I read in the archives (from "shogun") mentioned the brake bomb in the 750i here: http://www.bimmer.info/forum/showthread.php?t=10225&highlight=power+steering+pulse

I did not think any of the E34s had hydraulically assisted brakes... I don't remember any lines connecting the big brake booster to the power steering circuit, but I will check again in the morning.

Thanks again for the input
Andrew

pingu
07-29-2007, 08:13 AM
I'm pretty sure my 540 has the "brake bomb" so maybe your does too.

The reason why I think mine has a break bomb is that when my water pump broke (and the belt wasn't able to run the alternator or the power steering pump) my brakes were fine for the first few pushes but I soon lost power assist to the brakes. The engine was running so if the brakes were vacuum assisted they would still have worked.

Andrew
07-30-2007, 05:30 PM
Hey Guys

Just as an update, I have flushed another 2 $25 bottles of Pentosin CHF 11S fluid through the system and it seems to be helping. I still feel a little "perculating" sensation in the steering wheel (not so much in the brake pedal as before.) Hopefully a few more flushes will help this.

Also, thanks "yaofeng" for pointing me to the drain nut (HEX) on the pump... I did not know one existed. It makes the job much easier.

Finally, I looked at the brake bomb today and notice lines going into the intake manifold. This looks more like vacuum assisted brakes to me than hydraulically assisted brakes. (This is an American 540i BTW.)

Thanks again
Andrew

Ross
07-31-2007, 08:38 AM
The "brake bomb" is a pressure accumulator. Behind the left headlights on a 7er. If it has failed you will have a throbbing and likely low brake pedal. It's about $200 worth at your friendly BM dealer and another opportunity to spill pentosin.

BobHarris
07-31-2007, 12:49 PM
My UK 530 has hydraulically assisted brakes.