Power Steering Cooler - Anyone Fitted A Larger One To V35 Coupe?

[GeeDog]

Competed at a motorkhana yesterday, and had issues with the power steering. It was quite a hot day - ambient temp around 37 - and the event was on a large concrete truck parking area. My car's outside temp display got up to 41 while on the concrete surface, and I think this was fairly accurate. We had 2 drivers in my car, so it was doing twice as many runs, and from the start of the event we were 3 cars apart. This meant the car didn't get any cool-down time between me driving & my son driving. The first 4 runs were fine, but in the 5th run I noticed the power assistance dropped out a coupe of times - the steering just went really hard for a few seconds. In my son's run shortly after he basically had no power steering at all after the first turn. After this we organised to move his spot so that the car had a similar cool-down time between each run, and this helped but the power steer was still dropping out. In the end we didn't do the last run each because of it.

Now I know it was extreme temperature, and motorkhana is very hard on the power steering because you are going from lock to lock virtually the whole run, The problem was definitely heat related - after a lunch break the first couple of runs went ok, but the problem came back as the fluid got hotter. We tried using ice in plastic bags to cool the reservoir, which also seemed to help a bit.

I had to drive 80km to get home, and had no problems. I went out a few times today, and once again the steering is fine. The fluid smells a bit off, and is dark, so I'll be flushing & replacing it this week. I'm going to use Mobil 1 full synthetic ATF, which I hope will handle the heat a bit better. As far as I know the fluid is original, so a fluid change may well be all it needs. Because I have no way of testing until the next motorkhana event on a hot day, I want to replace the OEM P/S cooler with something a bit more effective, and maybe even fit a couple of fans that can be turned on for events and/or some ducting to get air directly onto the cooler. I'm looking at a PWR auto trans cooler - probably a 150x280mm or 200x280mm, which should fit where the factory one is now.

A google search shows this is quite a common problem for people with 350Z's in hot climate - ie Texas. They seem to use either Stillen or Nismo P/S coolers, but the prices are a bit over the top for something that's not much bigger than the factory cooler.

Has anyone changed the P/S cooler? What did you use, and what was the effect?

[Chris Rogers]

slightly different vehicle but same idea.

1996 subaru legacy GT. this car has a OEM tube that has fins for the PS lines. similar issue as you so I used a small V8 trans cooler on it. sorted the cooling issue out quite well when it was mounted directly in the airstream and I didnt boil the fluid anymore.

[scotty nm35]

A few of the M35 Stagea guys already know if you track the car you will need a PS cooler, as they have blown the pump. It doesn't have to be very big, I run a small 5 row motorcycle oil cooler and it's fine on even the hottest days at the track.

Definitely change the PS fluid, as well as dropping the engine oil. You should be glad you don't have temp sensors for them, you would have a heart attack over how hot everything gets.

[GeeDog]

Thanks guys - I'll get onto it this week. I had already fitted a large (280 x 200mm) trans oil cooler, but didn't think about the power steering overheating. Supercheap has a Davies Craig (same as PWR?) trans cooler on special this week.

[V28VX37]

A few of the M35 Stagea guys already know if you track the car you will need a PS cooler, as they have blown the pump. It doesn't have to be very big, I run a small 5 row motorcycle oil cooler and it's fine on even the hottest days at the track.

Definitely change the PS fluid, as well as dropping the engine oil. You should be glad you don't have temp sensors for them, you would have a heart attack over how hot everything gets.

Digging up an old thread - can a PS cooler be too big? I fitted a Davies Craig for my auto box back in the day and have gone manual since - do you reckon I could reuse this as a power steering cooler:

[scotty nm35]

Looks good to me, PS fluid can't really be too cold, it works fine when you first drive the car in the morning.

[V28VX37]

Looks good to me, PS fluid can't really be too cold, it works fine when you first drive the car in the morning.

Thanks Scotty!