Losing power assist when fluid warms up

[MrHorsepowerLSx]

I’m having an issue with my PS. I have assist while the fluid cool on a cold start but once I start turning the wheel a few times the fluid gets hot and I loss my
Power assist. I have a new redhead gear box, and I pulled the pumps relief valve and cleaned it out and did a fluid flush. The pump is a reman from another truck. the truck is currently being restored and my thread can be found in the 4x4 section under K10 Rustorstion.

I have this ailing suspicion that the new gear box is garbage

 

[MarineOne]

How old are the steering lines?

 

[MrHorsepowerLSx]

New

 

[rusted nuts]

New

Do You know if the power steering pump is good? I would make sure it isn't the pump before I brought and change the gear box. easy and cheaper stuff 1st.

 

[MrHorsepowerLSx]

Pump is new

I’ve replaced or rebuilt everything on the truck as it is being restored

 

[Snoots]

I hope you used PS Fluid and not ATF.

 

[MrHorsepowerLSx]

I did use PS fluid. I don’t use ATF in my pumps

 

[squaredeal91]

I heard from my local Napa that merc5 is good for powersteering pumps because they use merc5 to test rebuilt/new pumps. Just food for thought.

 

[rusted nuts]

Pump is new

I’ve replaced or rebuilt everything on the truck as it is being restored

Don't mean it's good just cause it's new

 

[MrHorsepowerLSx]

Don't mean it's good just cause it's new

Exactly. I’ve had problems before with “new” things being bad

Redhead tech center called me back, they said to run atf in the pump and swap the pump first before sending back the box. I’ll try that and report back

 

[MrHorsepowerLSx]

I heard from my local Napa that merc5 is good for powersteering pumps because they use merc5 to test rebuilt/new pumps. Just food for thought

I was told something very similar when redhead tech center called me back. They said they run ATF in the boxes because it runs cooler the standard PS fluid

 

[MrHorsepowerLSx]

Well after farting around with the truck this morning and digging through some parts boxes I had a hydroboost unit and pump assembly. I harvested the pump and swapped it into my K10’s pump housing after a through cleaning and tahhdaa!!!! Power steering is currently staying and not overheating in the housing. My steering is also WAY easier than last pump. The pressure relief valve had no washers under the valve so that means full pressure all the time until it dumps over the relief. Thanks to all who contributed

 

[Blue Ox]

I was told something very similar when redhead tech center called me back. They said they run ATF in the boxes because it runs cooler the standard PS fluid

Fine for the pumps, but it will make a hydroboost leak. Ask me how I know.

 

[MrHorsepowerLSx]

Fine for the pumps, but it will make a hydroboost leak. Ask me how I know.

…………..how do you know

 

[Blue Ox]

…………..how do you know

Funny.

We had two fail when the truck was new. The third one, we switched to PS fluid and it's still in the truck today.

BTW, the factory fill was Dexron. The manual called for it too. No mention of PS fluid.