To the best of my knowledge there is no filter on the return line. Not saying that's the issue, but could be a small restriction from something that is not normal in the system.

I kind of wonder if these rebuilt valves are getting built properly? Might be worth disassembling to see. This video is very good on how to rebuild the valve. Might discover something.

 

I believe that was last years post. But I was in the same boat as you, the only thing is that this is the second time this happens to mine. I am currently replacing my pw pump with one from Top Flight meant for my car and getting rid of Auto zone one. I am also replacing the control valve since I believe that is where restriction might be. I have already blown to high pressure lines. Possibly think my headers are the culprits heating things up, so I wrapped them with DEI wrap. Haven't finished project but we will see.

 

I have found a few posts on different sites concerning overheated P/S. I cannot find a solution. I replaced the original Control Valve with a new one to correct a small leak. Promptly overheated the pump in 10 miles. Damaged pump. Replaced pump with a rebuilt one from Oriellys Auto Parts and replaced the new Control Valve with another new one under warranty. Fluid ran to 300 degrees in 4 min of idling engine. Replaced 2nd Control; Valve with a rebuilt Control Valve, no change, 4 min of running and temp went to 275 and still climbing. Reinstalled original Control Valve with minor leak and P/S fluid temp was 175 after 10 min of idle time. Now I am back to where I started. Is there some sort of compatibility problem with Control Valve replacements? Not sure what to do next. Where is the best place to purchase a Valve from? I think the vendors get them from the same source. This simple job has turned into disaster. I am considering taking apart the Oriellys rebuilt Valve to see if I can dertermine a fault. Grasping at straws.

Michael

 

good info.. i would rebuild original valve.. not hard..as mentioned above.. take note of original and rebuilds.. i suspect not assembled correctly as mentioned
https://www.corvetteforum.com/forums...-question.html

 

These are positive displacement vane pumps. They need constant flow or they will overheat.
If there is no restriction, there is a lot of flow, but no pressure, and not much heat.
The ram control valve offers a restriction (when wheel turned) and this makes the flow drop and makes the pressure build. It can hit 1300-1600 psi.
There is also a pressure relief valve in the pump so it will not go too high and go over the set pressure, It then bypasses internally. The pressure makes heat.

I vote for it is making pressure all the time, with very little flow, because of some restriction in the PS control valve. It is constantly bypassing under high pressure in the pump, making heat. To overheat in 10 minutes must mean you have almost no flow. The control valve needs dissasembled, inspected, and carefully centered.
The pump will push almost 20 GPM if there is zero restriction. The first restriction is the control orifice in the back of the pump. 1.5-2.5 to 3.0 GPM rating, depending on application. That makes the pump build pressure to somewhere around 600-900 PSI at the back of the pump, even at idle, with the internal relief valve running 3/4 open and bypassing the rest. 900 psi makes testing the HP line very tricky.

The PS control valve further restricts the flow below 1.5 GPM, making the pressure climb even higher.

The return line is low/no pressure. You could replace that with some clear tubing for testing purposes. Or let it fill a jar and test the flow. Somewhere in the 1-2-3 GPM range. That's a gallon in 20 seconds. Just do not let the reservoir run dry, even for a couple seconds, or you will burn the pump vanes. It would take some "Mcguyver" engineering to do this at home and actually measure the flow. Simpler would be to just insert the return line flow into a big clear tube and then that tube into the pump, and just ensure you have a lot of flow, near 2 GPM. To heck with measuring it.

I have to believe the pressure relief spring/valve in the pump is working properly or you would have popped the HP line already. 1300 psi is normal when restricted.

GM PS by MotorTrend

 

Thank you for the info. I believe my heat problem is caused by the Control Valve. What I cannot understand is I have replaced the original valve with a new one from Oriellys Auto Parts.to correct a leak. After overheating the pump I replaced the the pump with a rebuilt unit and replaced the valve with another new one under warranty. After the second pump ran hot I replaced the valve with a rebuilt one from a different brand. Same problem. I am having a tough time believing 3 valves are junk. I installed my original valve and temps are running at 175 degrees after 10 min at idle. My plan now is top take apart the rebuilt valve and inspect it to see if I can determine the fault. Do you have any advise on what to look for during my inspection that might stand out as a cause?

Michael

 

Agreed. Having 3 bad valves in a row seems highly unlikely. There is a very specific procedure that must be followed to "center" these. Your problem is likely related to that. On center they should allow flow and not build pressure. But only on center. Immediately off-center the restriction would come into play, and cause them to build pressure. The "issue" could either be in the valve itself, or it's position being off-center when installed.

Have you run thru the adjustment procedure in the service manual? I believe it is done with the wheels off the ground?

I'll see if I can find it. Here is the control valve balancing procedure from the chassis service manual. Disconnect the power ram. Start the engine. When balanced "the control rod should be able to be moved in and out by hand" meaning it is getting no pressure applied to it.

In the testing section it also mentions it may take 5-10 lock to lock turns to get the fluid temp up to temp for testing 150-170. With that happening at idle it still sounds like too fast of a temp increase.

 

I actually disconnected the cylinder from the chassis mount so there would not be any drag on the cylinder to center it. Before disconnecting the cylinder I bled the system first with engine off by manually turning the wheels 20 times. Than started the car, adjusted the control valve to center and turned the steering wheel 10 times with the car off the ground and rechecked fluid. I am going to read the Valve Rebalancing pdf to see if I missed something. Thank you

Michael

 

I am so glad I have, and love, my factory manual steering. Don't have to worry about all this nonsense.....although plenty of other nonsense I have to worry about on my car(s). Sorry OP....I know my comments don't help your problem.......although....switching to manual fixes that problem, with no downside. Less junk under the hood, steers better, and handles like a Corvette should.

 

Wow. I'm stumped now too. You are right, this is a simple system and it will be a simple problem when you find it.

If the system has too little flow, that would max out the pressure, and the heat build-up.
The Corvette pumps run lower pressure than other chevys. Your rebuilt one may be too high. That is controlled by the spring in the back of the pump. And if the flow is also too low.... C3 870-1000....others 1350-1450... You could swap the spring back to the original one, and the flow orifice also.

They make gauges to check the psi, but it is easier to check the return flow, just clear tubing. But it's not very scientific unless you have something to compare it to. Unless it is very low and obvious.

 

I have comtemplated changing over to manual steering to rid myself of this diaster. Steering worked fine for 42 years until it doesnt. Im going to pour money and time on this problem until it is solved.

Michael

 

I am in the same boat, but after this last try I will possibly switch over to a Borgeson gear box.

 

Manual and Borgeson are both great choices. I have one of each!

I couldn't give the factory steering components away....

 

Been running into same issues wondering if you had found an answer or how your project is going?

 

I went through 3 power steering pumps, 3 control valves and, 2 rods from Azone. My PW pump would overheat or blow the pressure hose. So I said this time I was going to order a power steering pump from Top Flight made for corvettes with lower pressure. I can't remember their brand but it states corvette correct part (part#59767). I also replaced the Control valve and balanced it and took it a step further and put DEI wrap on my headers. NO MORE ISSUES. Knock on wood!

PS
Probably very important, I used Delco power steering fluid and
made sure I didn't overfill. I bleed the air out of the lines with the car off
the ground with no front wheels and rear tires still on the floor. So the air
bubbles would go to highest point which was pump.

 

I solved the overheat problem by buying an original GM control valve rebuilt by Lonestar Caliper Co. I went thru 3 control valves made in China? 2 new ones and 1 rebuilt. When I installed the Lonestar part the heat problem went away immediately. I checked tempertures in various area of the P/S system with a infrared thermometer. all is good. Lonestar will not take a core unless it is the original GM part. They will rebuild yours if necessary. I will never change a P/S part again without checking running temps. Junk parts cost me lots of lost time but I am now very educated on P/S.

Michael

 

And you're 25 lbs lighter! After a power steering leak nearly burned my car down I converted to manual steering and am happy to not worry about the seemingly endless leaks that are destined to occur w/this archaic system. Yes she's hard to turn when sitting but if you don't do a ton of parallel parking this is a great up grade. I can't find my notes but if memory serves me it was a 25 lb weight reduction to exchange pic 1 for pic 2. Sorry we're hijacking this thread but I'm happy w/this conversion.

 

I was almost there. I was looking at a new steering box from Borgueson or going to manual conversion. I was relluctant to make the change because the system has worked correctly for 42 years.

Michael

 

I hear you. I initially set out to repair my system and started researching this forum and was convinced that many had continuous probs after repair. Many don't of course. I'd imagine it has a lot to do w/part quality these days. But the cloud of smoke I was trailing and fluid spraying directly onto the exhaust scared the crap outta me and I was so lucky I was a block from home when it happened and not the day before when I was rolling down the hwy an hour from home on a HOT afternoon. My friends 66 396 Impala caught on fire the same way. Smartly he always carried an extinguisher so disaster averted. I on the other hand didn't and realized how fortunate I was to not catch fire. I kept the system and if I found NOS correct parts I'd seriously consider rebuild and re install. In the mean time It is one less worry and a little less weight. Keep in mind I drive the hell outta mine. I've put 14,000 miles on her 15 months and I stray pretty far from home every Monday so I need dependability over comfort in this regard.

 

Dont know if this is your problem but check your engine ground.When I installed a new crate engine and fired it up my power steering hoses on my Borgeson conversion started smoking.Traced it to ground cable not connected,engine was trying to ground thru pump.Connected ground ,no smoke and all is good