Power Steering Fluid Change Chevy Van

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Sep 18, 2002
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I went and got some OEM GM power steering fluid. Took off the skinny top hose and ran it to my gallon jug. Cranked engine, turned steering wheel and nothing happened. Nothing flowed.

Unhooked the big bottom hose from the reservoir. Reservoir drained out. So now both hoses going to the power steering reservoir are unhooked. Cranked engine again and nothing flowed.

My Toyotas don't operate this way. What is the deal? Steering feels fine.

How do I change the PS fluid in my 2008 Chevy Express 3500 Van?
 
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Well, I can't say exactly what is happening with your van, but I have never experienced anything like that! When the return line is disconnected the fluid has always squirt out into a bucket! Of course, I don't crank the engine for this...In recent years I just turn the key to RUN position and turn the wheels lock to lock a few times, and all the fluid comes out. I then replace the return line, refill with fluid, turn lock to lock a few more times, refill again, turn lock to lock a few more times, top it off, and call it a day. (I don't take credit for this technique. It was posted a few years ago on a Honda forum)
 
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Cranking the engine with both hoses disconnected won't do anything as your pump is already empty. Are you sure the hose you disconnected first was the return line? I think I've seen some of those GM trucks having three lines coming off the PS pump? Maybe the third was for hydraulic power brakes? I would figure out for sure which hose was which. Reconnect the high pressure side and refill the reservoir and you should get flow from the return line.
 
Hi Gebo. I believed you mentioned this is a 3/4 ton with a hydro boost. There are two return lines that go back to the reservoir. Put both return lines in the bucket. Use two chunks of rubber line with bolts in the end and plug off the nipples of the pump. Keep the high pressure line secured. You need a second person to help. Pour fresh power steering fluid in the reservoir will it is running. Move steering wheel back and forth. You have to keep that reservoir filled while it's expelling used fluid in the bucket. Google something like replacing power steering fluid in GM Hydroboost.

When you are done made sure you idle it while applying the brakes over and over.
 
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Originally Posted by Snagglefoot
Hi Gebo. I believed you mentioned this is a 3/4 ton with a hydro boost. There are two return lines that go back to the reservoir. Put both return lines in the bucket. Use two chunks of rubber line with bolts in the end and plug off the nipples of the pump. Keep the high pressure line secured. You need a second person to help. Pour fresh power steering fluid in the reservoir will it is running. Move steering wheel back and forth. You have to keep that reservoir filled while it's expelling used fluid in the bucket. Google something like replacing power steering fluid in GM Hydroboost.

When you are done made sure you idle it while applying the brakes over and over.



I can see and feel just two hoses. A smaller one coming out the side and a bigger one coming out near the bottom.The smaller one goes to the brake master cylinder, I think.

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The large hose is the high pressure line going to the hydro-boost unit. From the hydro-boost unit is a high pressure line going to the power steering rack. Now, there are two low pressure lines. One goes from the low pressure side of the hydro boost unit back to the pump reservoir. Another goes from the low pressure side of the steering rack back to the pump reservoir. Hook up that high pressure hose again and keep it hooked up. In fact if it was me I would hook everything back up and fill the reservoir. I would just do a Turkey baster job and pull fluid out and replace it with new. Run engine. Repeat.

But since you attempted this already, and the lines are disconnected, you can probably continue by having the two return lines in a bucket, and plugging where they where they were entering the reservoir. You picked one of the most sophisticated systems out there to do a power steering fluid replacement.

Knowing that van might be filled with people you should have a licensed mechanic inspect your work. The hydro boost is your power brakes. It that high pressure hose leaks you will lose your power brakes. Good luck.

Can a pro mechanic step in now? Thanks. Snag
 
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In photographs two and three there are two small braided lines. Are they going to your reservoir? Have to admit I've never seen braided line used as low pressure lines. Perhaps someone else can help out here.
 
Nope, there are only 2 lines going to the metal reservoir.

I've hooked everything back up. Drove about 5 miles and everything worked. I'll just do the turkey baster method.

I was just used to doing Toyota, Lexus, Honda, Acura.
I assumed this would be the same process. Unhook and extend top line to a gallon milk jug. Plug that outlet on reservoir. Suck out reservoir. Add new fluid and run engine and keep pouring in PS fluid til it runs our clean.

Well, once again ignorance wins.
 
The larger line coming out near the bottom of the reservoir goes down towards the bottom of the engine to what I considered the PS pump. The small line that comes out about the middle of the reservoir goes and hooks up to what appears to be part of the braking system.

I promise there are only 2 hoses connected to the metal PS reservoir. A big one and a little one.
 
OK, Thanks. So I take it those two braided lines had nothing to do with the power steering system . Not familiar wth the Van setup with a remote reservoir. And no issues, as both those those lines were low pressure lines, one to feed the reservoir to the pump and one to take low pressure returns from the hydro-boost. Good job Gebo. The only thing now is to repeat the turkey baster thing until your fluid looks good.
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And here is what your pump looks like.The top nipple would be where the large hose connects. The side nipple is where the low pressure return from from the power steering rack would go. I believe the back side of the pump has the connection to the high pressure line going to the hydro-boost. Someone correct me if I am wrong. Also to add one more complication I believe there is this simple power steering cooler between the power steer rack and the pump. Safe travels!

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Originally Posted by Snagglefoot
OK, Thanks. So I take it those two braided lines had nothing to do with the power steering system . Not familiar wth the Van setup with a remote reservoir. And no issues, as both those those lines were low pressure lines, one to feed the reservoir to the pump and one to take low pressure returns from the hydro-boost. Good job Gebo. The only thing now is to repeat the turkey baster thing until your fluid looks good.
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Yep, they were definitely low pressure. I'm gonna take a picture of where they go just for kicks.
 
Last pics for fun. The large hose goes down to that round looking contraption. The small hose (see the metal crimp clamp) goes over that black metal portion of brake master cylinder area.

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Snagglefoot, I really appreciate your time and effort. This was not definitely in my wheelhouse. I'm glad I bought 2 qts of PS fluid.
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THANK YOU!
 
Glad to help. I learned a lot about GM Vans. And yes your 2nd last photo shows the big hose going to the top of the power steering pump. On the last photo, it shows the aluminum brake master cylinder bolted to the black colored hydro-boost. Also, if you look to the left there is an aluminum cylinder looking item. That is your accumulator. If you every get a failure of the high pressure line going from power steering pump to the hydro-boost, that accumulator is storing pressure for one more "Hail Mary" push on the brake pedal. Very fitting on a Church Van I thought.
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Good luck and safe travels.
 
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IF you don't mind me asking. How is the PSF circulated? In simple terms. If I had both hoses off and fluid didn't run out of either, how was any fluid circulating and how could just hooking the hoses up cause the system to circulate?

I know it circulates because it took me three "DnF's" to get the PSF looking 75% clear.
 
Normally, the fluid in the reservoir is drawn down the large tube in the bottom to the pump. The pump sends it through the high pressure hose to the hydro-boost. If you would hit the brakes, a valve inside the hydro boost would feed pressure to a piston and that piston would push against your brake cylinder and assist your foot to send pressure to your four brakes. That is your power brakes. When you took you foot off the brake, the trapped pressure in the hydro-boost would be bled off to the RESERVOIR of the power steering pump through the low pressure line.

Now let's continue with the high pressure line as it leaves the hydro-boost. It travels to the high pressure side of your steering rack. It provides the assist to your manual efforts on the steering wheel and gives you power steering. Now if you keep turning the wheel back and forth, fluid would travel down to the low pressure line to the PUMP, NOT THE RESERVOIR.

Now this is where it is different from a normal pickup truck. In a pickup truck the reservoir sits on top of the pump instead of being a foot above it. The van used a remote reservoir because of space requirements. The pump is way down low so its needs a hose and a remote reservoir. When you removed the small hose and moved the steering wheel, no fluid came out of the hose. What was happening is that its the OTHER low pressure hose that returns fluid to the pump. It was doing its thing but you can't notice looking at the reservoir. Then, you unhooked the fluid the hose from the reservoir to the pump. The same thing was happening because the fluid spilled out of the reservoir but there was still fluid above the pump inside the hose and the pump was working but the fluid was just going back to the pump and you would't be able to see it.

If you wanted to try this again, you would take off the small hose that is connected to the pump (way down low) and direct it to a bucket. Then you can rotate the wheel while someone pours steering fluid in the reservoir. You would still not get all the fluid in the circuit to the Hydro-boost. For that you would want to do more research and do the hydro-boost properly. Hope that helps.
 
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