Power steering

[Mungo \Two Sheds\ Toadfoot]

Hi all,

1989 740 - the power steering is heavy when the engine is first started,
especially if I'm using the brakes (driving out of a parking space, for
example). Does the power steering use vacuum at all? This generally only
happens if the car hasn't been started for a few hours and the steering
returns to normal after a turn or two of the wheel.

The fluid level is fine.

Any ideas?

Si

 

[Michael Pardee]

Hi all,

1989 740 - the power steering is heavy when the engine is first started,
especially if I'm using the brakes (driving out of a parking space, for
example). Does the power steering use vacuum at all? This generally only
happens if the car hasn't been started for a few hours and the steering
returns to normal after a turn or two of the wheel.

The fluid level is fine.

Any ideas?

Si

The power steering is all hydraulic - no vacuum. What you describe is a cold
weather phenomenon that is usually called "morning sickness." The seals in
the rack shrink and don't let the pressure develop until they warm up a bit.
It will gradually get worse, lasting longer and happening at warmer
temperatures. Rack rebuild or replacement is the real cure, I'm afraid. Not
cheap.

Maybe somebody has had good results from a power steering additive that is
supposed to revive seals. At this point, it isn't likely to hurt.

Mike

 

[Mungo \Two Sheds\ Toadfoot]

The power steering is all hydraulic - no vacuum. What you describe is
a cold weather phenomenon that is usually called "morning sickness."
The seals in the rack shrink and don't let the pressure develop until
they warm up a bit. It will gradually get worse, lasting longer and
happening at warmer temperatures. Rack rebuild or replacement is the
real cure, I'm afraid. Not cheap.

Maybe somebody has had good results from a power steering additive
that is supposed to revive seals. At this point, it isn't likely to
hurt.

Thanks Mike, I'll see what I can find to pour in there!

Si

 

[Michael Cerkowski]

The power steering is all hydraulic - no vacuum. What you describe is a cold
weather phenomenon that is usually called "morning sickness." The seals in
the rack shrink and don't let the pressure develop until they warm up a bit.
It will gradually get worse, lasting longer and happening at warmer
temperatures. Rack rebuild or replacement is the real cure, I'm afraid. Not
cheap.

Maybe somebody has had good results from a power steering additive that is
supposed to revive seals. At this point, it isn't likely to hurt.

Mike

Our '88 240 has had this syndrome (in all weather) for a year or
more. I
added some power steering fluid conditioner last year, and it hasn't
gotten
worse. I can't look up the brand right now, but if you want I'll look
tomorrow.
--







http://freevision.org/michael/index.html

 

[User]

Thanks Mike, I'll see what I can find to pour in there!

Si

It was a common problem for many mfrs throughout the 80's and 90's. The
technicak name is morning sickness. The internal seals swell jus a
little bit when the oil is cold and shrink back down against once the
oil warms up. The cure was to replace the rack with newer type seals
that were less low temperature sensitive. If you turn the wheel all the
way from stop to stop a few times before driving off you'll force the
pump to produce maximum pressure and heat up the oil as it bypasses.

Bob

 

[John Robertson]

I have the same model and problem.It happens in cold weather and wont go
away as the seals are Teflon and wont react to special conditioners.Had it
for 4 years now learned to live with it .Rack rebuild is $$$$.
I brought the car in warm weather second hand .So when the cold came so did
the stiff steering.