PS fluid through in-rad trans cooler?

I'm installing a new radiator in my car, and since it's designed for manual and auto transmissions alike (I have a manual) I was wondering if I could run the power steering fluid through the trans cooler built into the radiator. Well, obviously I can, but is it a good idea? What's the typical operating temp for PS fluid? Will the ambient heat from the coolant in the radiator overheat the power steering fluid? My motivation here is that if this works out I can save the weight and headache of adding an external PS cooler to an already heavy car with a very cramped engine bay.

Thoughts?

wow wanna get married?

Sorry, but my dream girl has to know all the answers to questions about power steering fluid.

I have heard it recomended before, I'm just not sure if it was on this board or in a magazine several years ago. So yes, go for it.

have you ever looked under the hood of your car? ....the ps requires a reservoir the size of a coke can....forget the marriage proposal....duh

I have seen tubular liquid to liquid P/S coolers spliced into the lower rad hose on crown vics and ford trucks too. I didn't think that P/S fluid would get that hot in normal use, so hot that hot coolant would cool it, but apearantly it does. I would think that the cooler in the rad would be fine for P/S fluid cooling.

seepatty wrote: have you ever looked under the hood of your car? ....the ps requires a reservoir the size of a coke can....forget the marriage proposal....duh

The reservoir will still be on the PS pump, and there's even an overflow tank on the inner fender. Neither of those items will be eliminated, I'd just be putting the cooler (radiator) in line.

I'm now going to have to insist upon a dowry if you want to pursue this marriage thing further. I'll take mine in the form of an Elise.

My first thought is that I have never heard of power steering temp ever being an issue, even on race cars. It would seem that the coolant temp would actually heat the steering fluid up more than it usually is. I can't see steering fluid temps at 180 degrees, but I've never checked. Now I am curious. My rule of thumb has always been that if an 800 hp, 3400 lb stock car doesn't need it, then I don't either. It may be faulty logic, but it's worked very well so far.

my crown vic has a factory power steering cooler in the lower radiator hose so apparently there is some merit to doing such.

I'm not disagreeing with your conclusion, but by your logic fuel injection, ABS, treaded tires, transmissions with more than 4 gears, independent rear suspensions, headlights, opening doors and more are also unnecessary.

At any rate, something caused my car to blow its power steering reservoir cap off and spurt all the fluid out, sometimes after only one autocross one. Whether the fluid is boiling or the problem is elsewhere I don't know.

I have never run across over-temp problems. But I have seen over-pressure problems from sustained high RPM on the track.

The SVT Focus is know to blow a seal on one connector due to over-pressure. This can be fixed by changing the pressure relief spring and/or replacing the rubber seal with a copper washer.

I have been told that many of the AI Mustang people use a smaller (underdrive) pulley on the PS pump for the same reason.

My guess would be there is a restriction in a line or something in the system that is building up excessive pressure. If I was a gambler, I'd put money on the fact that is not temperature related, or else many other autocrossers would experience this.

Hal wrote: I have been told that many of the AI Mustang people use a smaller (underdrive) pulley on the PS pump for the same reason.

fyi underdrive of the p/s or any accesory would be a larger dia pully. or conversly a smaller pulley on the crank would underdrive everthing if all the other pulleys are unchanged.

Hal wrote: The SVT Focus is know to blow a seal on one connector due to over-pressure. This can be fixed by changing the pressure relief spring and/or replacing the rubber seal with a copper washer.

is it realy that easy? can this be done on many p/s pumps? I would like to learn more ,excuse the threadjacking...

Some cars have issues with PS fluid temp...usually heavier cars. Most cars can get away with not running them, even under racing conditions.

If you want to run the PS fluid through the cooler, I don't see why not, if there's a pressure problem you'll know it.

Yes, heavy cars...this is a 94 Thunderbird SC that weighs about 3,500 before I get in it, and I autocross it on Hoosiers.

HappyAndy wrote:

Hal wrote: The SVT Focus is know to blow a seal on one connector due to over-pressure. This can be fixed by changing the pressure relief spring and/or replacing the rubber seal with a copper washer.

is it realy that easy? can this be done on many p/s pumps? I would like to learn more ,excuse the threadjacking...

It didn't really solve the over-pressure problem, just kept it from blowing the seal. Not sure it this could be applied to any other car.

of course the fluid gets hot, ever seen a hydraulic line break on a tractor or backhoe or something? that stuff gets hot for the same reason you use an intercooler on a forced induction setup. if the fluid gets hot enough that it boils once pressure is released (like when it goes from the high pressure side in the rack to the return line), and it keeps boiling all the way to the reservoir, i'd bet that could blow the cap off pretty easily.

fwiw, my f150 had a factory power steering cooler for a 4000lb truck on 225 series highway tires stock, so im sure it can't hurt with a 3500 lb car on hoosiers

Depending on the radiator the power steering system pressure may run too high for the cooler.

That being said I would recommend running the return line from the steering gear to the radiator then to the resevoir.

Should be fine.

Will wrote: At any rate, something caused my car to blow its power steering reservoir cap off and spurt all the fluid out, sometimes after only one autocross one. Whether the fluid is boiling or the problem is elsewhere I don't know.

I'd say that's a damn good bet. I was having similar fluid issues in my autocrosser. Changing to a high grade synthetic fluid reduced it, adding a cooler (air) totally eliminated the problem.

Curiously, my pump uses ATF, so it stands to reason that a cooler for ATF (in radiator) would be adequate and appropriate for PS fluid...

I'd like to mention that my post makes it sound as if this only happened once. I've actually been fighting this all year and have had to withdraw from a few events because of it. It's been annoying.

John Brown wrote: Depending on the radiator the power steering system pressure may run too high for the cooler. That being said I would recommend running the return line from the steering gear to the radiator then to the resevoir. Should be fine.

i agree, i probably should have been more clear in my post, i dont think the radiator or its associated fittings would appreciate 1000+ psi for very long

At a rallycross in June, I had a co-driver. We got 12 runs each...

I boiled the power steering fluid in my crown vic.

I recommend it.

As for the pressure, I was thinking of connecting the cooler to the low pressure side of the rack and the pump. It's not as if PS coolers don't exist, so as long as it's done properly, pressure isn't the problem with this idea. I'm still just thinking about temps.

well the boiling point of hydraulic fluid, which is basically what PS fluid is, has to be a lot higher than the temps that it would be seeing in the radiator.