Power steering questions

[smdk2500]

I didn't mean to be argumentative - just thought adding to the confusion was a good idea!

Don't worry I didn't take it as you being argumentative. I

 

[smdk2500]

Does the presence of Hydroboost and/or EVO steering influence cooler fitment?

Just a guess again I don't think so. Both my 95's have different brake boosting systems. One is vacuum and the other is hydroboost.

 

[HotWheelsBurban]

Yeah, I have no idea how it was determined if they got the PS cooler or not. I went and looked at my GM trucks and they all have them. They are as follows:

99 Silverado 1500 ECSB 2WD with 4.3 LS
00 K3500 CCLB SRW with 5.7 LS
06 Suburban 2500 2WD with LQ4 LT

Neither show an RPO that matches PS cooler. In fact, the suburban even has a engine block heater, so it does not seem that it would be a "hot state" option. As far as I thought, it was standard on trucks?

Could it be related to trim? Maybe just coincidence? I think the 2 earlier trucks are sort of a "nice trim" option, and I think LT in 06 was as well?

I can't recall the early GMT 400 trim options. Was it Cheyenne and Silverado in Chevy and respective SLT and SLE in the GMC Sierra? What about SUVs?

Chevy Burbs in 95-99 are either LS( velour cloth seats) or LT ( leather seats). I think the GMC s had SL, SLT, and SLE, like Sierra, Sierra Grande, and Sierra Classic in the square bodies. I recall seeing 400 series trucks with Scottsdale, Cheyenne and Silverado cab post badges, the GMC s had the previously mentioned trim level on the cab post emblem.

 

[Schurkey]

My 89 K2500 has the longer "cooler" type hose that snakes into the frame and back.

My '97 K2500 7.4L also had the "cooler" that is nothing more than bent tubing that pokes into--and then back out of--the left-side frame rail behind the front bumper.

At the point where I bought the truck--about 150K miles and a year-and-a-half ago, the tube had worn through. The entire underside is now coated in power steering fluid and dirt. I disconnected the plumbing to that tube, looped it together, and at least for now I have no plans to replace it.

IF at some point I do put a steering cooler back in, it'll be a tube-and-fin or similar cooler, not just a bent tube crammed into a frame-rail.

 

[Supercharged111]

My '97 K2500 7.4L also had the "cooler" that is nothing more than bent tubing that pokes into--and then back out of--the left-side frame rail behind the front bumper.

At the point where I bought the truck--about 150K miles and a year-and-a-half ago, the tube had worn through. The entire underside is now coated in power steering fluid and dirt. I disconnected the plumbing to that tube, looped it together, and at least for now I have no plans to replace it.

IF at some point I do put a steering cooler back in, it'll be a tube-and-fin or similar cooler, not just a bent tube crammed into a frame-rail.

Just swipe a sticker from the boneyard if you're so inclined. They package so nicely.

 

[Schurkey]

Just swipe a sticker from the boneyard if you're so inclined. They package so nicely.

Sorry, I don't understand.

 

[gearheadE30]

Sorry, I don't understand.

Probably meant swipe a stocker and got autocorrected.

My Tahoe Limited has a factory power steering cooler. It is on the driver's side of the cooling package and is a finned cooler that is the full height of the rest of the cooling package. It's just a long "U" section, and the fins cross over the "U". Inlet and outlet are both at the bottom. It's pretty significant as far as PS coolers go. This truck does not have hydroboost. I would guess that the 9C1 trucks have it too.

Our trucks use a fixed-displacement vane pump to run the steering hydraulics. These pumps are rated in a flow per revolution, meaning that flow increases roughly linearly with RPM. The pump is sized so that it has enough oil flow to be able to run the power steering at idle without losing pressure, the value of which is determined by either a fixed spring pressure relief valve or an electronically-variable valve that we all refer to as the EVO valve. For the purposes of cooling, it doesn't make much difference which setup you have.

As engine speed increases, the amount of oil flow that has to be bled off over the relief valve increases, which generates proportionally more heat. In a case where you are driving straight, nearly all of the power consumed by the PS pump is turned directly into heat, which has to go somewhere. Most of us don't run very high RPM all the time, but in say a police pursuit application or some other car at a track day or autocross running at high revs all the time, it's very possible to actually boil the PS fluid. I have done it before on my cars, and have seen it on numerous others. On vehicles with Hydroboost, this is a really big deal because it means you also lose your brake assist. My guess is that GM picked and chose which vehicles got a PS cooler as a cost control, and had either no cooler, a low-cost cooler, and a more effective high-cost cooler for the top end stuff.

I think the basic cooler might have been part of VYU snow plow prep package, and possibly others as well. I think the one on my Limited is probably a part of the Z60 option.

This is the cooler most GMT400s would have had if they have one at all:

You must be registered for see images attach

This is what the GMT800s got, which is almost identical to what my Tahoe Limited has:

You must be registered for see images attach

 

[HawkDsl]

Yep.. that top one is the one I got. Pretty sure that one is standard on the C 3/4 tons, and all the K models.. regardless of other options. The headache with that one is, you have to remove the front bumper to get it out. The "Non-cooler" type will also fit... It's similar to the return line, and you don't have to remove the bumper if it starts to leak or burst. As Gearhead said, it's a good idea to have some cooling. Even thought it's a pain, I've always replaced mine with the cooler type.

The factory "cooler" type is gonna be OK for a daily and some 4 wheeling.. Probably not for a rock crawler or giant tires

Best thing you can do is change out the fluid every year. PS is one of those "Add and forget it" fluids it seems (like the brake fluid, sadly). That stuff gets seriously nasty over time.

 

[Supercharged111]

I wonder if the frame loop is specific to the earlier TBI trucks?

 

[454cid]

I wonder if the frame loop is specific to the earlier TBI trucks?

That was my impression, too, but Shurkey posted that his 97 had the loop.