[Dick Boneske]

My '64 GTO has the original pump (with new front seal, "O" rings) with a IROC Camaro steering box from NAPA.

Power steering works fine for about 10 minutes after a cold start. Fluid heats rapidly (at idle with steering wheel centered). Pump is quiet until fluid gets hot--then whines when turning the steering wheel or revving the engine when wheel is centered.

System now has power steering fluid as NAPA recommends instead of Dexron.

I've driven the car about 25 miles since steering system has been in place but heat and whining problem does not appear to be getting better.

I have a power steering pump control valve from a late '70's Chev pickup truck, which used the variable ratio faster box. Will this help my problem?

If not, any ideas on how I might correct this problem? Adding a steering fluid cooler is not an option. These cars had no coolers on them when new and should not need one now.

[Txbobcat]

I think I would try the Dexron. If that doesnt do it add some some Lucas power steering additive after that.

[Kell]

Are you sure you got all the air out of the system? if not, jack up the front while running and slowly go lock to lock SEVERAL times.

good luck

[Dick Boneske]

I've turned the wheel lock to lock dozens of times with and without the engine running. The system works fine when cold, never overflows, does not leak at all.

After about 15 minutes, it whines, assist is jerky like a loose belt, and the hoses are too hot to touch.

I have a '70's Pontiac pump also. Today, I checked the high pressure outlet fitting and noted it has a oil inlet hole (.140" vs. .130") and different design (large tapered oil inlet) than the '64 fitting. the newer outlet fitting has two holes on its outside diameter which the '64 fitting does not have. In addition, the hole at the flared pipe connection is .250" on the '64 pump and .182" on the newer pump. The spring in the rear of the pressure regulating valve appears to be the same for the '64 and newer pump.

In the newer pump, the pressure regulating valve that bears against the spring has two shim washers instead of one on the '64 valve.

Those are the differences I can see between the two pumps. I understand the '70's series pumps operated at 1400 psi vs 900 psi for the older pumps. This must be established by the spring in side the pressure regulating valve.

[Kell]

Originally Posted by Dick Boneske

After about 15 minutes, it whines, assist is jerky like a loose belt, and the hoses are too hot to touch.

This sounds exactly like air in the system, that is what mine did, took a long time to bleed all the air out.

However, it sounds like you can change out the valve easily to test as well. They (the PS expert I talked to on the phone) say it has little to no effect on steering effort but something to do with pressure like you said. I put an IROC box on mine as well, steering effort is pretty high but is way better than the station wagon feel of the old one. I put a newer style pump and valve on mine at the same time so I can't say on the valve part.

[Pontirag]

could be that the pump is worn and cant maintain the pressure the box needs to operate.

newer boxes place higher demands on pumps, older pump designs and wear could be the problem. while there is a very appearent visul difference between a new square looking pump and an older bottle looking pump, thats not where the significnce lies. the newer pump housings are one piece hosings that are welded together. The older bottle style pumps were soldered together.

it was discovered that high effort steering boxes generated enough heat to cause the soldered joints in the housing to melt and fail. accident and fire hazzards.

Just a heads up there. Maybe remove and install the later pump in the older housing.

I dont recomend dextron as a rule. others may but I read enough to know there is a significant difference between PS fluid and tranny fluid. maybe mix the two in an emergency but not as a rule.

[Dick Boneske]

Thanks to all for the info! It makes sense to try the other pressure control valve and outlet fitting. The '60's pumps are identical to GM's pumps 20+ years later, so different control valve components should make the pump work with faster ratio boxes.

I believe the soldered joint is the sheet metal "neck" soldered onto the pump housing (reservoir) on these early pumps. I've heard of this joint melting under severe duty such as circle track racing.

As many of you know, all the '60's GM cars specified "Type A Transmission Fluid" (Dexron) ONLY to be used in the power steering system. It was many years later that the same components were still being used, but "Power Steering Fluid" was specified.

[Pontirag]

maybe the box is compatable with dextron.

[john31s]

I just read through this and I'm wondering, when did GM move to the pumps with welded housings?

[59safaricat]

Originally Posted by Dick Boneske

System now has power steering fluid as NAPA recommends instead of Dexron.

There's your problem right there. Your whining issue is a common occurrence with even newer cars (like Toyotas) where power steering fluid is used when ATF is called for by the manufacturer. Flush the hell out of system with ATF and pray no permanent damage has occurred.

A side not about fluids. I initially used Dexron in the pump when I got my '59 running after sitting for 25+ years. The pump reservoir was pretty much dry and I filled and burped it with Dexron. The Dexron leaked pretty quick (remember, Dexron has gone through several revisions and the fluid gets thinner with each revision). I ended up filling the pump with some Type F fluid I had left from servicing the dual coupling trans. Not only did the power steering perform better, especially at lower speeds, all of the leaks mysteriously quit.

[Pontirag]

I think theres more to it than that. with the cost of power steering parts being what they are, I prefer power steering fluid over tranny fluid.

I cannot see how type f is better than dextron for an unintended application.

I use Power steering fluid in my Toyota and it only whines when the reservoir is empty

to each his own

[59safaricat]

Originally Posted by Pontirag

I cannot see how type f is better than dextron for an unintended application.

Type F is a thicker oil, which is what obviously took care of the leaks in my half a century, all original power steering system. Perhaps the higher viscosity is what helped the system perform better too I DO know that Type F accurately mimics the old Type A fluid better than Dexron; especially when it comes to use in older transmissions.

Originally Posted by Pontirag

I think there's more to it than that. With the cost of power steering parts being what they are, I prefer power steering fluid over tranny fluid. I use Power steering fluid in my Toyota and it only whines when the reservoir is empty to each his own

I still have the original 28 year old Dexron II ATF oil in the power steering reservoir of my Toyota pickup (with almost 300,000 miles) that it came with from the factory. No discoloring, no leaks, no noises, never added a drop of fluid to it, and never a repair anywhere on the entire system. Sorry, but I fail to see any issues with using ATF fluid, especially if the manufacturer calls for it

[Dick Boneske]

I know from experience both types of fluid will work. The fill cap on a '64 GTO power steering pump says "Type A Fluid Only." It worked in these systems for millions of GM and other brand cars. Since that time, Type A fluid has been improved---viscosity improvers, better lubrication, better detergent properties.

And, common sense tells me that the synthetic fluids--Type A or Power Steering Fluid, are better than the petroleum-based types of either.

In any case, I'm interested in correcting the overheating problem. Substitution of the later-model pressure control valve is my best bet. I'll report on success when it's done.

[rexs73gto]

When I put P/S on my 68 Firebird I put in ATF to start & it never made any noise. I installed a quick ratio gear from a 88 Tran Am. It worked great & I never had any problems with it. Now back in the day to show the difference we use to use type F in the trans to make it shift harder because with the reg. dextron got hot to fast & let the trans slip a bit. But when we used type F we could run hard at the track all day with out it slipping any. Type f is strong in a trans designed for reg. dextron. So thats why you want to use it in your P/S to help keep it cooler & qiut because of its properties.

[Pontirag]

Lots of opinions here.

whether we agree with each other or not is not the point

best bet is to go with what the manufacturer recomends, in terms of fluid choice and service intervals

I do prefere synthetics when its a viable option

[Dick Boneske]

Problem is fixed!!! As I mentioned in the OP, I replaced the control valve in the '64 GTO pump with a '70's vintage later model valve that operates at 1400 psi max instead of the '64 pump's 900 psi. This valve is accessable by removing the pressure line from the back of the pump, removing the 1" hex fitting that the hose screws into, and getting the valve body out of the pump with a magnet. It is not necessary to remove the pump.

I sucked as much power steering fluid out of the reservoir as possible with a suction gun. Removed the pressure line from the pump and unscrewed the old control valve and replaced it with the later model one. Refilled system with Mobil I synthetic automatic trans fluid. Turned the wheels from lock to lock six times before running the pump. Ran pump and turned lock to lock six more times. System works perfectly with no more noise and no more overheating.

I was dragging my feet on replacing the control valve because I didn't want the mess from fluid dripping out of the hoses/pump. There was very little mess after doing the changeout as I described above.

[6 Grrrs]

Interesting that I stumbled onto this thread today. I have a similar issue with a 1967 GTO. Completely stock P/S system that the pump was leaking and the reservoir needed reconditioned. The system worked fine before dis-assembly. I got a pump kit and rebuilt the pump. Once reassembled, I performed the bleeding procedure, working the wheel from lock to lock about 20 times total (20 each way L+R). When I started the car everything seemed OK. Once the car warms up, the system works randomly. Sometimes there is assist and sometimes not.

This car had what looked like trans fluid in it before I started. I put p/s fluid in and noticed what was in the box started to mix with the p/s fluid. I then pulled the pump back apart to make sure I got everything in properly. I know if the eccentric is backwards, the pump will not work properly. I have had the pump apart several times now. The last time I took it off/apart, I put the hoses in a bucket and worked the steering wheel from lock to lock to evacuate all of the trans fluid out of the box. I then turned the box to the far left lock (which is where it is suggested to start when bleeding the system).

I then reinstalled the pump, filled it with p/s fluid, and performed the bleeding process again. This time all seemed correct. Took the car for a ride and as I was backing into my driveway, the system started to whine (faintly) and now I have intermittent p/s again.

Could it be that I need the trans fluid in this system to work properly?

One thing to note it the pump was stamped 'reman' in yellow, behind the pulley. There were a few numbers as well. Clearly this is not the original pump, but the system worked fine when it came in here.

Any help would be appreciated.

[59safaricat]

Originally Posted by 6 Grrrs

Could it be that I need the trans fluid in this system to work properly?

Wouldn't hurt to try and the only cost is about 2 quarts of trans fluid.

I'm really curious about the results, so please post up any new findings if you go through with it.

[6 Grrrs]

Originally Posted by 59safaricat

Wouldn't hurt to try and the only cost is about 2 quarts of trans fluid.

I'm really curious about the results, so please post up any new findings if you go through with it.

Sorry for taking so long. Been very busy lately.

I emptied the pump and evacuated the box again and refilled with Dextron III (I had an old, unopened bottle - probably 10 years old - and figured it would be closer to the old Dextron). No change.

I removed the pressure valve and replcaed with the original from my '66. No change.

I disassembled the '67's original pressure valve and found a small piece of dirt in it. Reinstalled, and no change.

I have the pump off of my father's burnt 1964 GTO hardtop. It burned up in a house fire 5 years ago. The car has been sitting outside with no real protection. About 3-4 weeks ago he & I went over to it and cut the hood open. We removed the tripower intake and carbs, Shroud, PS Pump, Alternator, and some other misc stuff. Surprisingly the motor still has oil in it (no water), and the antifreeze in the heads/intake still was nice and green.

I basically pulled the pump out of the reservoir, swapped the big oring and the 3 little ones from the rebuilt '67 pump, and put it on the '67. The power steering works as it should and does not leak. Crazy that it sat 5 years and did have a little water in it (pressure valve was stuck in compressed state, once I got it out, I cleaned all the rust off of it), but it works like a champ!

I'm assuming that something is not correct in my rebuild. I have had this pump apart 6-7 times total and everything appears to be correct/undamaged. I am going to pickup a rebuilt pump and install it. My father wants to keep his '64's pump for a spare for his catalina.

Engine pic of burnt '64 for you guys...



Exterior pic...

[General Z]

Going to drag this old post up. What’s a part number for the higher pressure valve?