Power steering diagnosis

[Dr. Rog]

Hi folks

Sometimes when I start the car the steering is stiff, it sort of judders as if the pump is intermittently not working.

I do have a bit of a squeal off of the belt , which is pretty tight. My dealers mechanic said that it was well tight enough and was noisy because the pulley was polished smooth and the belt new. It has been improving as the belt wears in.

Another fault it could be is seized track-rod end or ball joint, but it frees up in minutes and once ok drives fine.

What are the usual issues with these cars? Is there any good tests?

Cheers

[heyskull]

Well I've just change both track rod ends and checked everything else and its nice and free.
Ive been told its the rack dying!!
Its a shame as it isnt leaking.
Is their not something i can add into the fluid to make it last a little longer?
It seems to be worse in the morning and even worse when weather is cold.

[volvoz2000]

nicknamed morning sickness for a reason..... tired racks gentleman

[Paddy Wagon]

Your symptons indicate low fluid level in the pump. I know it sounds basic, but, most people check power steering fluid level the wrong way, ie, with the engine OFF,,,, you have to check it with the engine RUNNING because as the pump operates it pulls fluid into the system and lowers the fluid level in the pump resovoir. What may seem the correct level with the engine off is actually low enough when running to allow air to get into the system, this is what causes the intermitant action. After a few minutes as the fluid warms up it expands, the level in the resovior goes up and no longer allows air into the system, thus "apparently" fixing itself. A loose drive belt can also give the same symptoms but they would be accompianed by a high pitched chattering/squeeling sound, but the belt would have to be noticably loose to do this. It's very unlikely (although not impossible) to be the rack. Generally the only problems you get with racks are a blown seal, in which case the power assist is gone , end of story, or the gearing can seize or break. If it is starting to seize up it will get progresively worse,,, it wont judder, it will just get heavier and stiffer. The only time in 32 years as a mechanic I've encountered a rack that caused the symptoms your getting was a due to a faulty torsion valve, it's a little device in the rack that reacts to steering wheel movement and directs the power assist left or right. This one had become a bit brittle and until it reached normal operating temperature it was very jerky in it's operation and caused the same problem your getting. The best way to check the PS fluid level is to remove the resovior cap first, then start the engine, preferably when cold, dont rev it, turn the wheel about a quarter turn left then a quarter turn right and then back to center to prime the hydraulics, then check the fluid level.

[Dr. Rog]

Amazing. (thanks button has disappeared, so thanks for that. )

I shall check that - it must be one of the easiest things to do.

[Dr. Rog]

Originally Posted by Paddy Wagon

A loose drive belt can also give the same symptoms but they would be accompianed by a high pitched chattering/squeeling sound, but the belt would have to be noticably loose to do this. It's very unlikely (although not impossible) to be the rack.

The best way to check the PS fluid level is to remove the resovior cap first, then start the engine, preferably when cold, dont rev it, turn the wheel about a quarter turn left then a quarter turn right and then back to center to prime the hydraulics, then check the fluid level.

Tried it this afternoon, the car had not been started for days. No luck with the level. It stayed resolutely static on "full".

The belt is still squealing, so my money is on belt slippage. Its nice and tight, so the question is do I need to rough up the pulley, fix the leaking water pump, replace the pulley or the whole pump?

[Paddy Wagon]

Originally Posted by Dr. Rog

Tried it this afternoon, the car had not been started for days. No luck with the level. It stayed resolutely static on "full".

The belt is still squealing, so my money is on belt slippage. Its nice and tight, so the question is do I need to rough up the pulley, fix the leaking water pump, replace the pulley or the whole pump?

Ahh, a leaking water pump, that could cause your problem, if the leak is excessive then water could be getting onto the pump pulley causing it to slip and squeal like a pig. Another thing is it could simply be a duff fanbelt. I've come across it a few times where a suposedly good belt slips and squeals regardless of how tight it is, it might be worth fitting another belt if the pump leak is not excessive, but certainly consider sorting out the pump before it gets any worse.

[Dr. Rog]

Well the pump is definitely on the "next job" list.

I may have to pay someone though, run off my feet at the moment.

(Then why am I sat the PC??)

[jlawler]

I have the same problem on my aging 740 (1989, 235k). I gather it is referred to as "morning sickness" by some Volvo people and is due to worn seals on the torque vale.
Not much you can do to it (other than change the rack) though mine improved a bit after changing the oil. Reconditioned racks (return old one) used to be about £170 in Eurocarparts.

Years ago I hung a strong magnet in the reservoir to pick up any bits of metal that wear in the system. Its surprising the dust that sticks to it.

[Alasdair1]

I just changed fluid in mine and it made a big difference. It was particularly bad on cold mornings. I wonder if there was some moisture in fluid. Seems ok now and a lot quieter on full lock.
Alasdair.