GREAT FORUM... I have searched the topic here and elsewhere but haven't found a solution. I suspect the pumps flow control valve is allowing too much pressure. The pump was failed when I bought the car and the owner didn't have the history on the pump that was in it so I can't be sure I have an original flow contol valve for it. I have replaced the pump twice since June and I have had two failures due to overheating. I have also replaced the PS Contol Valve and balanced the system per the manual and no change. I currently have an aftermarket pump on it with the valve that came with the aftermarket pump. I suspect the aftermarket pumps are supplied with a generic flow control valve that puts out 1300 psi where I read that it should be about 950 for this system. The steering works OK other than being too sensitive at higher speeds. After starting up cold the pump gets too hot to hold your hand on it after 3 to 5 minutes at idle (same as the other two pumps that failed). Anybody know where I can get a pump flow control valve calibrated properly for this system or a replacement pump that I can be sure has the proper valve? The suppiers I have talked to can't provide information about the pressure and flow settings on their pumps. Perhaps that is why they suggest to use your "old" valve if it doesn't work properly. Any help is appreciated.

 

I might have an old Corvette pump that I wouldn't mind pulling the valve out of for you. I can sell you the whole pump or just the valve components. I won't be able to look to know for sure for a few days...been super busy with work which means lots of sales road trips. If you don't mind waiting I can re-post here Monday and let you know for sure what I find that I have at home.

 

Thanks Durango boy

I will wait to hear from you.

 

I have one for-sale right now, came off my 1980 L82

 

The Corvette pumps 1974 through 1981 had a flow of 2.9 gallons/min at about 1200 pump rpm which is relatively high flow for a Saginaw pump. The pressure relief settings for all C3 pumps were 950 psi.

The 2.9 gpm is primarily determined by the size of the throat in the discharge fitting #24. The 950 psi relief pressure is determined by the shims that are under the hex head fitting in the flow control valve #6 inside the pump (more shims lower relief pressure - less shims higher pressures).

You only reach maximum relief pressures when you are at near full lock and the car stopped with the brakes applied. The problem is that the Corvette hoses were not designed for pressures over 1000 psi. So if you have a higher relief setting in your flow control valve, you could fail the hoses as you approach full lock in a hard parking lot type turn.

The higher relief setting will not have any effect on steering feel or effort since it only comes into effect near full lock. Driving down the road and making just small correctional turns should only cause your pump to develop a couple hundred psi pressure max.

Having said all this, and the fact that you have gone through two pumps, I don't think that you have a pump problem. It seems to me that you have some type of restriction in your hoses (a sharp bend or kink?), the control valve, or possibly the pump reservoir (a kink in the return spout on the reservoir?).

I wish that I had more definitive answers with respect to your problem.
Jim

 

You mention that you have "experienced two failures", but didn't mention the failure mode/symptoms. You also mention that the failures were due to "overheating". Was the oil 'cooked' or did the pump just 'feel' hot? You can't leave your hand on anything over about 130-140 F degrees...but that's not hot at all, as far as your P/S pump is concerned. I'm just not clear on what failed and what the failure symptoms were.

 

Thanks for all of the replies & information.

Both pumps that failed started to leak at the input shaft seal and the remaining oil in them smelled burned when it was drained. I assumed that the overheating caused the failure. I have replaced the hoses and I am sure they are not kinked. Funny thing is the power steering works fine but the pump heats up so fast I am sure it is not normal. The third pump is doing the same thing and I don't want to drive it and blow it too. I have used the flow control valves supplied with the reman pumps. My understanding is that at idle with no steering load on the pump it should be in bypass mode and just circulating fluid at relatively low pressure through the steering control valve. Troubleshooting leads me to the flow control valve as the next part to change.

Anybody want to sell just the flow control valve from their pump?

 

If you're still looking for one by Monday I will sell you just the valve.

 

I'm going to suggest that a different fault may be the real cause of your problems. If the shaft seal leaked on both 'bad' pumps, I think the orientation of the pump to the drive pulleys might be off. If the P/S pump is "side-loaded" and runs that way continually, it would put undue stress on the shaft support and probably cause some heating in that area. Check the alignment of the pulleys in the system and also verify that the belt is not overly tightened. I just can't see the same failure mode happening to two separate pumps, and being due to the same faulty component. There has to be a 'common cause' that lies somewhere else in the system.

 

Thanks for the suggestion. I will check that out.

 

On the Saginaw P-pump there is a bushing inside the nose of the pump that supports the driveshaft. There is also an oil groove in the bushing. The oil groove must be oriented such that it is located in-line with the pull of the drive belt. Otherwise there will be insufficient lubrication of the bushing and the driveshaft seal.

The remanufacturer of the pump must know the application where the pump is to be used and should know how to orient the groove in the bushing.

Now most Chevrolet engines have the pump mounted low on the driver side of the engine. So the pull of the drive belt would be pretty much the same and the location of the oil groove should be pretty standard for most Chevy pump applications.
Jim