steering groan

[username]

My 1988 E30 (119k miles) has developed a cold weather groan in the PS system. I tried to replace the reservoir as the filter is not independently replaceable. I also tried to flush out the old fluid and replace it with new synthetic fluid. It still groans as the temps drop close to freezing here. After some warm up though, it is much less likely to groan. It also is more likely to do so when standing still as opposed to moving. When I look into the reservoir, I see plenty of foaming when this happens. The level appears OK too.

What is the likelyhood that the problem is in the PS pump or the steering rack ? The pump was my initial thought until a colleague mentioned that racks get worn and can make the pump work much harder - making the noise.

[Wayne 962]

Foaming and groaning means a lack of fluid. When you typically see this, you have a system that isn't getting enough fluid for some reason. I would check the lines to make sure that they are clear - also crack them open at the rack and let them bleed out a bit.

It may also be a problem with the pump not pumping enough fluid in there, but I doubt it.

-Wayne

[kuehl]

Originally posted by username
When I look into the reservoir, I see plenty of foaming when this happens. The level appears OK too.

What is the likelyhood that the problem is in the PS pump or the steering rack ? The pump was my initial thought until a colleague mentioned that racks get worn and can make the pump work much harder - making the noise.

As the Chief pointed out it sounds like a fluid issue first.

Foaming in the tank means air is mixing with the fluid.
Normally the fluid should not have any air. If the tank level is full you would want to locate a point where the air can get into the system, and this would typically be the "low" side or return side from the rack back to the tank. This means everthing in between (such as lines and pump).

Start off by checking the hydraulic line fittings on the rack's pinion valve body housing (aluminim housing). There are four lines attached there, two will be attached at other points on the rack and the other two will attach to the lines that go to the pump and resv. tank.

The fittings, known as "banjo's ( because they look like a banjo when you take the bolt out) will and should have aluminum or copper crush washers on each side of the banjo fitting... for the fittings connecting to the hoses to the pump and to the resv. tank. There are two other metal hydraulic lines on the rack, these will have a banjo affair however they will have o-rings on each side of the banjo fittings. If your pump is pulling in air it could becoming from the "return" line banjo fitting of a fitting that sees a low pressure at some point in operation.

Next follow the return line from the rack to the resv. tank. It is not uncommon to have a cracked hose, lose hose clamp or swollen hose at the tank, which is another source for air getting in with the fluid.

Then you would check the hose and fitting points between the power steering pump and the resv. tank.

And finally, not common, but we have seen times when the case seal o-ring between the pump half's is the source sucking for air.

Unfortunately when pumps start mixing air with fluid you get Cavitation. Cavitation is when there are bubbles in the fluid. As the air is compressed out of the fluid you get small shock waves that slam against or cause the vanes in the pump to slam the vane guides and pump surround..... this leads to a noise and a worn pump rather quickly and metal contamination in the whole system which is difficult to remove.

[username]

Thanks for the replys - I will check the lines and connections

[koya1893]

My 1984 318i did the same thing. During my winter check on the car I did belts tension check and adjusted all the belts slightly tighter than they were the noise stop afterwards. so you might want to check the belts tension it might be one that needs to be alittle tighter I thought mine was tight enough.

Ben