Power Steering Issue

[o2bad455]

I checked the steering effort in 6 sequential tests turning lock-to-lock (quite the workout) while parked:

1) SVT controller disconnected engine off
2) SVT controller disconnected engine running less than 5 seconds
3) SVT controller disconnected engine running more than 5 seconds
4) SVT controller connected engine off
5) SVT controller connected engine running less than 5 seconds
6) SVT controller connected engine running more than 5 seconds

There was no discernable difference. In every test I had to use both hands and throw some of my weight into it for at least the last half turn of the steering wheel. Oh well, at least it was a good workout.

I just realized I probably should have checked/cleared codes after plugging in the SVT, since one of the first 3 tests could have set a code and I can't say for sure that it wouldn't have affected the outcome of tests 4-6.

Might do that and retest 4-6, do a 9V test from the inside connector, and/or run it long enough to measure PS fluid temp changes after I eat.

[RocketyMan]

Thanks for the update. Can you confirm connection to the SVT? What are you using to view the modules? Just ISTA?

[o2bad455]

I only have ISTA (not ISTA/P yet) working in English. I have INPA too, but it's mostly in German. I've used the old INPA on the X5, but only the newer ISTA on the X3. Since the SVT shows in the ISTA tree view, I believe it's connected. But yeah, if I could translate the German perhaps using INPA might be more definitive.

The PS temp didn't rise very quickly, so I'm beginning to suspect a sheared pump shaft (possibly from the yearly outdoor temperature drop combined with my questionable choice of top up fluid that might well have been thicker when cold).

Our X5 is down for a different issue (rusted rear brake lines where packed into plastic case on arm that apparently catches salt and mud - terrible design IMHO but that's a project for another day). So I need to either get this X3 sorted today or admit defeat for the long weekend (to include too much parallel parking).

Pulled from the local junkyard a greasy PS pump out of a 2007 X3 (that was already missing it's intake mani, making my job unexpectedly easy). Less than $20 CAD including tax, to boot! The pump pulley has the same detail as ours, so I think it's the right one. I checked the rack on the donor and did not see any servotronic valve (or I would have grabbed that too). I turned the used pump while removing it and it definitely had good resistance and even moved a little fluid.

I checked Canadian Tire and then Walmart looking for CHF-11S fluid. Neither really had it, although Walmart can ship the Pentosin CHF-11S (to US or Canada) but I didn't have time to wait for that. Called nearest BMW dealer despite 1 hr drive and they were surprisingly out of stock (the parts guy opined that service got more hydraulic PS repairs than usual when the cold snap hit). I remembered using a full synthetic PS fluid in a VW/Audi engine years ago, so called the local VW dealer. VW apparently used the CHF-11S from about 2000-2005, and the local VW dealer had one 1L bottle left among their stock of CHF-202. The CHF-202 is apparently a synthetic blend that can go into any VW (including those with 11S as original fill), while the CHF-11S is full synthetic. VW part number for the full synthetic seems to be G-004-000-M2. It was over twice the price of today's used pump, but at least it gives me a fighting chance.

Collecting my thoughts about getting around the intake manifold and then heading out to swap the pump momentarily (well, as soon as I'm done procrastinating). Fingers crossed!

[o2bad455]

It's fixed! I replaced the pump, the reservoir, and the two lines that connect directly to the reservoir. I was able to do it all just by removing the air filter box and the cables from the alternator (after disconnecting the battery again). The old pump felt okay when I spun it, although I haven't pulled it apart to see if there's anything obvious wrong inside. So the problem was either the pump itself, the non-replaceable filter inside the reservoir, or possibly what seems to be a one-way valve or restrictor in the front line (the one with quick-connect) that comes into the reservoir.

[RocketyMan]

Originally Posted by o2bad455

It's fixed! I replaced the pump, the reservoir, and the two lines that connect directly to the reservoir. I was able to do it all just by removing the air filter box and the cables from the alternator (after disconnecting the battery again). The old pump actually felt good, although I haven't pulled it apart to see if there's anything wrong inside. So the problem was either the pump itself, the non-replaceable filter inside the reservoir, or possibly what seems to be a one-way valve in the front line (the one with quick-connect) that comes into the reservoir.

Great news! So your suspicions of the pump itself was correct. I was thinking that if any pumping were to be happening, that the working fluid would atleast be getting warm.

I'm not too sure HOW important the "green" hydraulic fluid is in comparison to ATF. Some people say that it'll make the seals swell and start to leak. Otherwise, ATF probably would've been fine to at least troubleshoot with. There's really not too many additives in ATF and I doubt there would be that many in 11S neither. A nice VOA of 11S would be great.

I guess a couple take away's from this is that if the SVT communicates on the BUS and has no fault codes, the ABS reports rational road speed, the servotronic in the PS line should be working. I'd be curious now if you were to do you same test of measuring the working fluid temperature if it would be much warmer than last time.

[o2bad455]

Originally Posted by RocketyMan

Great news! So your suspicions of the pump itself was correct. I was thinking that if any pumping were to be happening, that the working fluid would atleast be getting warm.

Thanks! To be honest, I'm not sure if my suspicion was right or just wishful thinking. There's no abnormal feel or noise from the old pump, so I was actually worried that I guessed wrong until I buttoned it up and was pleasantly surprised that it was fixed. I really didn't want to have to R&R the rack!

Originally Posted by RocketyMan

I'm not too sure HOW important the "green" hydraulic fluid is in comparison to ATF. Some people say that it'll make the seals swell and start to leak. Otherwise, ATF probably would've been fine to at least troubleshoot with. There's really not too many additives in ATF and I doubt there would be that many in 11S neither. A nice VOA of 11S would be great.

Actually, I think the fluid I'd used for top-up a while back actually was CHF-11S, just in a smaller bottle (355 ml instead of 1 L). It was green too. Anyway, I'm sold on the full-synthetic CHF-11S. I don't like the idea of swollen seals from modern ATF. I've seen too much of that on other cars already.

Originally Posted by RocketyMan

I guess a couple take away's from this is that if the SVT communicates on the BUS and has no fault codes, the ABS reports rational road speed, the servotronic in the PS line should be working. I'd be curious now if you were to do you same test of measuring the working fluid temperature if it would be much warmer than last time.

Agreed. It seemed electronic to me, but apparently only because I'd never had a PS loss with no other symptoms before. The SVT control seemed a likely suspect, especially after discovering the servotronic valve, but it turned out to be a red herring! Go figure...

I'll measure temps again to see if it's much different. Come to think of it, I'd only measured temps just before, in and just after the reservoir this morning becuase those were easily accesible, but probably should have measured just before at and after the pump, possibly from underneath. I believe the PS fluid goes through a cooling loop before it reaches the points where I'd previously measured.

Honestly, the more I think about it, I probably just lucked out today... But I'll take that!

[RocketyMan]

Originally Posted by o2bad455

Thanks! To be honest, I'm not sure if my suspicion was right or just wishful thinking. There's no abnormal feel or noise from the old pump, so I was actually worried that I guessed wrong until I buttoned it up and was pleasantly surprised that it was fixed. I really didn't want to have to R&R the rack!



Actually, I think the fluid I'd used for top-up a while back actually was CHF-11S, just in a smaller bottle (355 ml instead of 1 L). It was green too. Anyway, I'm sold on the full-synthetic CHF-11S. I don't like the idea of swollen seals from modern ATF. I've seen too much of that on other cars already.



Agreed. It seemed electronic to me, but apparently only because I'd never had a PS loss with no other symptoms before. The SVT control seemed a likely suspect, especially after discovering the servotronic valve, but it turned out to be a red herring! Go figure...

I'll measure temps again to see if it's much different. Come to think of it, I'd only measured temps just before, in and just after the reservoir this morning becuase those were easily accesible, but probably should have measured just before at and after the pump, possibly from underneath. I believe the PS fluid goes through a cooling loop before it reaches the points where I'd previously measured.

Honestly, the more I think about it, I probably just lucked out today... But I'll take that!

Well it makes sense if the pump goes. The TIS has quite a big warning about holding the steering wheel in the "locked" position for too long. This is VERY hard on the pump as there is no relief when the steering gear is trying to press all it's pressure on the locks. Once that happens, this causes a no-flow scenario and will then "burn up" the pump. Or in this case, the veins scar the housing, thus, no pressure being able to be produced.

You checked for SVT codes and didn't find anything. There is no "pressure sensor" in the steering--so it makes sense that if the module isn't complaining that the only other probable cause would be the pump since there is no feedback for pressure loss, other than no assist.


Here is a very limited PDS of the 11S:
http://www.pentosin.net/specsheets/Pentosin_CHF_11S.pdf

Then something comparable like this for Valvoline MaxLife ATF:
https://sharena21.springcm.com/Publi...2-ac162d889bd1

Other than both being synthetic, the two have very similar viscosities at temperature. I would expect them to behave the same. Until a VOA of 11S proves otherwise, I'm not convinced it is much different. But ohwell...a topic for a different thread.