1994 525iT steering frozen at temperatures below 30

[werminghausen]

Interesting- good call
I will try again replacing the fluid with 4L of ATF.
As I said before I replaced the fluid 2 times now- but may be not enough. I have Valvoline synthetic fluid in right now.
What makes you believe I had the Pentosin in the car?
Of course if the car was originally a Pentosin car and was converted then there might be a problem... me putting PS fluid in. I can exchange the fluid several times in order to make sure that the fluid is clean and not mixed . I guess with this I can eliminate the question of mixed fluid.
I have the question for the ones who know. How can I know that my car originally had the self leveling system and using Pentosin? What are the indicators?
Martin

in

If you have checked the drive belt and it is tensioned correctly.
Go get about 4 litres of ATF fluid and suck out your old fluid (it could be Pentosin!).
You can use a turkey baster to suck it out.
Refil the reservoir with the new ATF.
Start your engine and turn the wheels lock to lock a couple of times. Then suck out the fluid. Refill with fresh ATF and, again, do the lock to lock with the engine on.
Do this about 4 times and you will replace a lot of the old fluid.
Provided your pump is not shot, this SHOULD clear out most of the old fluid......

[genphreak]

Plastic type reservoirs are often ATF, the CHF11S one has a sticker (a green ring) on the top. CHF7.1 ones have a yellow ring (Beware: they come off with age). e34s with metal reservoirs (almost... ) always use CHF11S. e32 had more exceptions to this rule than e34. e23/24/26/28 I don't think used CHF11S much (but there were some with LAD whihc would have. Anything with LAD or SLS will use CHF11S and share a modified power steering pump, as it is best to use the one very high pressure hydraulic circuit (which is why they use CHF11S). From BMW's POV, the only expensive bit in this approach is the multi-purpose HP Pentosin oil.

Since you are not using the reccommended fluid, you should try swapping your synthetic ATF (is that what you are using- not synthetic something else?) to Mercon or Dexron.

I don't think it can be your steering box. Pump maybe... but I'd be surprised if it was. You can probably get a $20 kit for it from www.pskits.com.

[werminghausen]

Plastic type reservoirs are often ATF, the CHF11S one has a sticker (a green ring) on the top. CHF7.1 ones have a yellow ring (Beware: they come off with age). e34s with metal reservoirs (almost... ) always use CHF11S. e32 had more exceptions to this rule than e34. e23/24/26/28 I don't think used CHF11S much (but there were some with LAD whihc would have. Anything with LAD or SLS will use CHF11S and share a modified power steering pump, as it is best to use the one very high pressure hydraulic circuit (which is why they use CHF11S). From BMW's POV, the only expensive bit in this approach is the multi-purpose HP Pentosin oil.

Since you are not using the reccommended fluid, you should try swapping your synthetic ATF (is that what you are using- not synthetic something else?) to Mercon or Dexron.

I don't think it can be your steering box. Pump maybe... but I'd be surprised if it was. You can probably get a $20 kit for it from www.pskits.com.

I have the black round plastic tank from ZF. There were no labels at all.
Again the question what are indicators that the car was a Pentosin car originally?
I think the fluid that I have now in the tank is synthetic Valvoline PS fluid.
Someone recommended to flush with 1 gallon of AFT. Probbaly a good recoommendation . I'll do this with ATF Dexron III.
This will make sure I don't have any mixed fluids. And go form there.

[genphreak]

Best to just drain the fluid at the lowest point in the system if you want to efect a full change. I think that is the lowest line on the steering box, but it might be the pump, just look.

Of course if the car was originally a Pentosin car and was converted then there might be a problem..

Easy to do, just look at the lines going to the steering box. Do any follow the (US drivers side) rail back under the cabin to the rear? LAD deleters usually just replace the rear shocks and join the hydraulic lines at the back near where they reach the subframe. Sometimes they leave the height switch which operates off the sway bar and even the accumulators, both of which are very obvious.

Or do a VIN check. Or goto www.realoem.com and enter yor car's VIN to see if the parts listings show LAD components as valid for your car, or simply the conventional shocks. This is in no way as reliable as looking in the flesh- and realoem is often incorrect/vague or simply hard to work out

[genphreak]

I just dug up the old reservoir. It says clearly : ATF only !
So my assumption is that the car came without the self leveling system.

Further assumption: The reason for bad performance at low temperatures is either the pump or the PS gear box. Any suggestions?
Martin

The seals fail in the pumps, maybe affecting low temp first.
0. Make sure the serpentine belt is OE spec- a Continental- may be worth buying from BMW as BillR has reccommended as they may have a closer tolerance (may no longer be true tho?).
- Correct type (1560-1580mm is allowable, obviously you want to be on the tighter side)
- Has a strong OEM tensioner- does it spring back smoothly and hold a strong tension?

Once you know the answer to these you may have it.

If not...
1. Goto PSkits.com - Power Steering Rebuild Kits for Pumps and Racks and get a $20 repair kit.
2. if that doesn't help, you may be able to try synthetic Pentosin (CHF11S), low temp capabilites is the likely reason a manufacturer would opt to use such 'obscure' fluids in the first place...
3. Post your results for the world to know

Good luck...

[Mr._Graybeard]

GM rack-and-pinion systems had problems like this for years -- it even acquired a name: "morning sickness." The seals in the steering gear hardened and let fluid leak internally when cold, robbing the system of its power boost. Once the fluid warmed up a bit, it restored some flex to the seals and power boost returned.

Is the steering equally stiff turning in each direction?

[werminghausen]

GM rack-and-pinion systems had problems like this for years -- it even acquired a name: "morning sickness." The seals in the steering gear hardened and let fluid leak internally when cold, robbing the system of its power boost. Once the fluid warmed up a bit, it restored some flex to the seals and power boost returned.

Is the steering equally stiff turning in each direction?

Yes..my steering is equally stiff in each direction and each position no matter how far you turn the wheel.


So could it be that my steering gear box is damaged?
This sounds like a possibility? The symptoms you describe are exactly the same with my car.
Is there anyone who knows about a defect of the steering box? Most of the people say that it is not very common that the steering box fails.

I feel a bit awkward because hardly anyone does report the very same problem on their BMW. But if there are more people- who else is experiencing the same problem on the BMW??



Martin

[werminghausen]

I put the car on ramps and inspected from below.
The oilpump has 2 lines- definitely not 4
There is no line going to the rear axle
There is not a trace from the LAD on the rear axle.
I have regular struts.
I believe there was never any LAD on this car.
And it seems to be weird if any Pentosit were in the system at all.
Anyway I'll flush again and use up to 1 gallon of ATF just to make sure that the fluid is clean. And I'll report back.

[Tiger]

I took a look at the onlne auto parts... seems like you got traditional steering system rather than rack & pinion system... so it is either your power steering pump or your steering gearbox... it is most likely the pump need to be rebuilt.

Check the belt tensioner for that includes power steering and make sure it is nice and tight.

[Mr._Graybeard]

Yes, the car in question has a gearbox rather than a rack, but all steering systems have some similar basic components -- seals, pressure-relief valves,etc. -- that the hydraulics require to operate.

Anyway -- Tiger's thinking PS pump, I'm guessing steering gearbox. Either way, fairly big bucks to fix -- not something that you want to just throw parts at. You could try another fluid change -- it's cheap, and if it doesn't work you aren't out much.

There's one other option, considering that you've been living with this for a couple of years. There are a number of additives you can put into a PS system that can soften up the seals a bit and restore some elasticity -- Lucas and Bar's Leaks are a couple of manufacturers. It's not a repair, but it might make the condition a little more bearable.