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Power steering and power brakes struggle when idling ‘78 Eldorado

Started by Tornike, August 18, 2018, 01:50:53 AM

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Tornike

I drove my ‘78 eldorado for a first time. No more than a mile just to check few things.
Here’s what I found that I hadn’t noticed before:
1. Power steering and power brakes worked just fine while driving as low as 10mph, or even when idling initially.
However, after just shy quarter mile of driving, when I was to back up, the power steering started having hard time. I put car in reverse and while idling I started rotating the steering wheel, simultaneously hitting the brakes. PS started making a noise and became heavy, until I put car into park, revved the engine, making the PS light again and rotated wheel that way.
I’m also hearing squeaking noise coming from power steering pulley area (update on the squeak: looks to be from the lowest pulley connected to Air pump + fan belt).
Could that be a faulty belt or something else?

2. When I put the AC on I literally felt some vibration on a brake pedal. And PS seemed to become slightly less happy too. Again, belt?

3. After 15 minutes of driving at 10-20 mph when I parked the car it was vibrating pretty noticeably while idling. If I put AC on or rotate steering wheel, it would become slightly worse. Suggestions?

I haven’t changed any fluids yet. Where would you recommend starting?

Julien Abrahams

I would first chck the idle speed. It could be adjustedtoo low. Related tothat i would check fo rvacuum leaks causing the idle speed to drop. It won't hurt tocheck the belts and the tension of the belts. If they are slipping you will hear it loud and clear as they will squeal. Good luck
1954 Cadillac series 62
1967 Cadillac Sedan De Ville HT
1969 Austin Healey Sprite
1979 Opel Kadett

TJ Hopland

Making sure you are not idling too low in gear is a good thought.  Also make sure your belt isn't slipping.   

If you have not done it already exchange as much of the PS fluid as you can with fresh stuff.  The booster is more sensitive to the fluid than the steering.  Its also first in the chain and has a regulator sort of valve in it that if it sticks can bypass too much fluid.   I have had them that getting fresh fluid in em and carefully using them helps a lot.     

Does the pedal feel odd over the entire stroke or does it just get the chatter when you are at that almost stopped position?   

StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Tornike

Quote from: TJ Hopland on August 18, 2018, 09:21:29 AM
Making sure you are not idling too low in gear is a good thought.  Also make sure your belt isn't slipping.   

If you have not done it already exchange as much of the PS fluid as you can with fresh stuff.  The booster is more sensitive to the fluid than the steering.  Its also first in the chain and has a regulator sort of valve in it that if it sticks can bypass too much fluid.   I have had them that getting fresh fluid in em and carefully using them helps a lot.     

Does the pedal feel odd over the entire stroke or does it just get the chatter when you are at that almost stopped position?
It feels odd over the entire stroke without even pushing the brake pedal when I turn the AC on after driving a little.

Roadmaster75

Your power steering pump also provides hydraulic power to your brakes.

Sounds like that pump needs a rebuild or replacement......its talking to you!
Check shop manual for operation and symptoms.


V63

Loose or slipping belts would cause your symptoms.

Air pump might be binding up?

If not...

I might verify that the hoses are not restricted internally before rebuilding the pump. I have heard of folks mistakenly adding brake fluid to the PS...this would damage the entire system if enough was added. It causes all the system rubber to swell excessively.


Scot Minesinger

Mike is right power steering pump also makes the brakes power (vacuum is not used on a 1976 Eldorado to make the brakes power).  The belt that powers the steering pump also powers the ac compressor. 

You need to check of course the power steering belt, power steering pump, ac compressor/clutch, idle speed adjustment and of course vacuum leaks.  If there are major vacuum leaks after they are fixed, idle speed and timing will need to be checked again.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Tornike

Starting to change fluids hoses belts etc this weekend. Getting the service manual on Friday. Also got the paint to paint plastic fender fillers. Will post results in a separate post.
Back to the topic - I played with my car more today and got more specific details on the issue.
Basically power steering is very light and silent for first 5-10 minutes after cold starting the car when parked. I haven't put car in gear at all. After 5-10 minutes when the engine warms up it's idling speed drops (engine becomes very silent and runs smooth - no shaking or anything), and this is when power steering starts to struggle. I have to rev the engine in order for power steering to operate smooth.
Could it be that engine in gear is idling too low (even though it's in park) or has some vacuum leak as Julien suggested? Or sounds more like a belt slipping issue? Will get into changing the belt hopefully this weekend, but want to get as much insight beforehand as I can.