Power Steering Tank Boilover

[Frank D.]

Just finished rebuilding the power steering control valve and slave cylinder as part of a restoration. Did not rebuild the pump as it was working fine. Fired up the car for the first time and while making idle adjustments, smoke came up from the front of the engine. The fluid in the power steering reservoir had boiled over. Checked all the obvious things, belt tension, the writing on the bottle of fluid itself, etc. Started it up again, with the same result (wash, rinse, repeat).

Just finished reading all the posts on both boards and most mention two solutions: mis-matched hose connections and faulty control valves. Re-checked the hose connections, and they are all correct. Before we go through the process of removing and dissasembling the control valve, there was something that made no sense. Upon crawling under the car to check the correct routing of the hoses, I expected them to be hot to the touch. They were not hot at all, whereas the body of the pump was as hot as an exhaust manifold. It appears there was no fluid entering the hoses coming out of the rear of the pump.

Any ideas/knowledge you might have to share?

As always, thanks for being here!

Frank O'Donnell
Troy, VA
See you at the Nationals (well, maybe...)

[Jim S.]

Re: Power Steering Tank Boilover

With the engine at idle and no steering input there should be free flow of oil out of the pump; down to the control valve, and back to the pump reservoir. Within reason the pump reservoir and the hose pipes should be relatively the same temperature with the free flow of oil.

Is your pump making a lot of noise with the engine at idle and no steering?

A lot of times if you have pump reservoir overflow it is because you didn't "get the air out" of the system before starting the engine. With a lot of air in the components (even though you may have filled the reservoir before starting the engine) the big air bubbles get pushed through the system and then everything gets whipped to a froth as the large air bubbles pass through the pump. Air and oil (foam) takes up a lot more space than just plain oil. So the pump reservoir overflows with lots of creamy colored oil. (However, this explanation does not account for your description of a very hot pump reservoir and cool hoses.)

It seems to me that the most likely explanation is that you misassembled the control valve and it is not allowing fluid to "free flow" through the valve. This would cause the pump to heat up but not the hoses. It also should cause the pump to make a lot of noise as soon as the engine is started (even without any steering motion.)

Again, this probably has nothing to do with your problem, but I always recommend that you refill the power steering system with genuine GM power steering fluid. The fluid available at GM dealerships. It has excellent anti-foaming characteristics and is specifically formulated to operate with Saginaw power steering pumps (the ones in all of the C2, C3, C4 Corvettes.)

Jim

[Frank D.]

Re: Power Steering Tank Boilover

Jim:

Thanks for responding. I read your post and have been working all day to fix the problem. The pump was making lots of noise when it boiled over the first time. We had to add p/s fluid a couple of times upon initial start-up, thinking the air was working its way out leaving more room in the tank.

We are disassembling the control valve tonight to see if we assembled it wrong.

Thanks for your quick response. Will keep the post updated.

Frank O'Donnell