losing power steering under acceleration

[swisherred]

OK...back at this again. I'm still losing power steering under heavy pedal.

I rebuilt the pump, replaced the belts, removed any and all paint on the pulleys...changed the fluid, rebuilt the steering valve...all of this made it better each time, but I'm still losing it under heavy pedal. Any useful Thoughts here?

side note, I still haven't had an alignment done after rebuilding the entire front end. Could this have anything to do with it? getting that done later this week.

 

[rkrochen]

I only have a couple of thoughts.
First of all it sounds like the belt may be slipping. How tight is your belt, is it the right width of belt so it sits in the groove properly and make sure that your not at the end of the adjustment.
Secondly it could be a relief valve popping off when you get additional flow.
I really can’t see how an alignment would help but you should have one anyways.

 

[swisherred]

I only have a couple of thoughts.
First of all it sounds like the belt may be slipping. How tight is your belt, is it the right width of belt so it sits in the groove properly and make sure that your not at the end of the adjustment.
Secondly it could be a relief valve popping off when you get additional flow.
I really can’t see how an alignment would help but you should have one anyways.

I used the original 1/2" wide belt to start...seemed to ride high in the pulley...so I switched to a 3/8 to get it deeper...little better....then I sanded the pulleys to remove paint and that helped. Switched back to the 1/2" and it was a little better. No clue about how tight it is. My torque wrench died recently....but I have under 5/8" deflection.

 

[swisherred]

Relief valve?

 

[Davea Lux]

Have you replaced the hoses, the inner liner of the pressure hose will sometime detach and cause a blockage.

Dave

 

[rkrochen]

I used the original 1/2" wide belt to start...seemed to ride high in the pulley...so I switched to a 3/8 to get it deeper...little better....then I sanded the pulleys to remove paint and that helped. Switched back to the 1/2" and it was a little better. No clue about how tight it is. My torque wrench died recently....but I have under 5/8" deflection.

A quick test would be to try and tighten it up a bit more. If it works then you know what the problem is. The deflection test is tricky unless you know how much pressure to apply. There are actual tools made for this.

 

[swisherred]

I have not replaced the hoses. They had been replaced already and are pretty new..not that they couldnt be bad I guess...I found the deflection specs...new belt 1/8" under 5lbs load...I will double check that. somewhere i have a deflection tool. If that doesnt fix it then i will replace the main hose..

 

[FinFury]

I have had the same problem with federal pump on my challenger for the past 10 years. The sudden change in steering effort really wakes you up when going sideways at high rpm. I am following closely if you find a way to solve the problem.

I really haven't tried to solve it because it's quite close to the end on my neverending todo list. I did buy a rebuild saginav unit and new mounts I was planning to install when I find a pulley for it.

 

[swisherred]

I guess I should say it is a federal pump...if that matters. Can the unpressurized return hose cause any issues? I know mine is old..hard...hasnt been replaced yet.

 

[swisherred]

I also replaced the return fitting on the gear box...cant remember what its called...angled aluminum thing...

 

[swisherred]

just replaced the lower return hose...it was clear, but I replaced it anyway...no change. This leaves the supply hose as the only thing that hasnt been changed or repaired....unless there is something else causing it.

 

[swisherred]

can anyone tell me about the return fitting with the check valve in it.....I dont know how it functions or what its purpose is. I replaced it, but new doesnt always mean correct.

 

[swisherred]

I even took the valve apart and swapped the internal springs with the original ones in case they were different strengths because I found that there was a low pressure and high pressure version....no change.

 

[Big_John]

I have under 5/8" deflection.

That's a lot of deflection for a fairly short belt. I'd say that's your issue.

new belt 1/8" under 5lbs load

That's probably right, but what I would do is tighten the snot out of it (That's a technical term) and try it. Running the belt really tight isn't great for the pump long term, but if you tighten it up so there's no possible way that it's slipping, and you still have the problem, that's not what's going on.

I'm also thinking that the pump bracket might be the problem. The two piece bracket can be troublesome and may let the belt loosen or you think you have the belt tighter than it actually is.

 

[swisherred]

That's a lot of deflection for a fairly short belt. I'd say that's your issue.



That's probably right, but what I would do is tighten the snot out of it (That's a technical term) and try it. Running the belt really tight isn't great for the pump long term, but if you tighten it up so there's no possible way that it's slipping, and you still have the problem, that's not what's going on.

I'm also thinking that the pump bracket might be the problem. The two piece bracket can be troublesome and may let the belt loosen or you think you have the belt tighter than it actually is.

Yeah...I tightened the crap out of it and still the same issues. I'm within spec on deflection now...I think the next thing is to change the hose...just don't want to randomly change more parts without knowing why its the problem. I have another steering box and valve I can swap in if needed too.

 

[Davea Lux]

Here is an article on the flow valve: Benchworks Steering Systems Guide to Diagnosing Problems with Pump Pressure Relief Valve | Benchwork Steering Systems
It sounds like your flow valve in the pump is closing too far on the rise of pressure caused by increasing engine RPMs.

Dave

 

[swisherred]

OK...now...maybe that is it. I will look into that one.

 

[1970cat]

what fluid, and is there any foaming in it?

 

[swisherred]

Fluid has been changed when I rebuilt the pump. Full flush and bleed...no foaming..basic orielys power steering fluid...no atf...although I know previously it had some atf in it when I bought it.

 

[1970cat]

just wondered if it was cavitating under high rpms due to improper fluid or worn vanes.