Plug power steering pump to bypass it? Pressure question.

[DejaVue]

Trying to figure out how to separate the power steering pump (fluid) from the steering rack but keep the pump pulley lubricated for the serpentine belt.

The intent of this is for the mid-2000s years Volvo 2.5T engine, but it's applicable to most engines.

People remove, bypass, delete the power steering on their cars for various reasons. It's easy to do on an engine that has a separate pulley belt for each accessory. And easy to do on serpentine-belt vehicles that can remove the pump entirely and use a shorter serpentine belt. And on vehicles with aftermarket support to remove the pump and replace with just an aftermarket pulley to take the pump's place.

But what to do on other vehicles? If power steering pumps put out a high psi on the outlet line, is it ok to just remove the line and screw a plug into the pump to seal it off? (and keep the feed line from the power steering fluid reservoir intact to keep the pump lubricated.) The high pressure from the now-plugged outlet line shouldn't damage the pump internals, should it?

Does the pump even output much pressure when the wheels aren't being turned? If not, then plugging the output hole would just keep it in low-load mode all the time.

I've also heard of people taking pumps apart and removing the vanes or similar from the internals, so the pulley still spins, but the fluid inside the pump isn't being pumped at all. I'd rather just screw a plug in where the output line was though, if the high pressure won't hurt it.

 

[Colt45ws]

I definetly wouldn't plug it. PS pumps are positive displacement. Meaning for every turn on the input it WILL output X amount of fluid. Usually measured in ccs/rev. Plugging the output will do nothing but make all that fluid its trying to pump have no where to go, and it will pressurize until the relief valve opens. That just dumps it back to the suction side, so its circulating the little fluid thats in it and making it hotter and hotter while at the same time loading your accessory drive all the time, which if you are bypassing it is definietly Not What You Are After.
I would take the output and go straight back in to the reservoir. Fill it and it will just circulate the fluid with no head pressure.

 

[DejaVue]

I forgot to ask about that option, of looping it to the reservoir. The concern on that one is can the plastic factory reservoir handle the pressure the output line is sending into it? Normally, the reservoir is fed from the fluid exiting the power steering rack, at (from as far as I know) a much lower pressure compared to the pump's output pressure. You said looping it to the reservoir would circulate the fluid with no head pressure, but I don't know enough about power steering pumps to understand why the fluid coming from the reservoir wouldn't be at the same high pressure as the fluid being pumped into the reservoir since there's no power steering rack to reduce the pressure in the loop.

Even if I plugged the output end of the pump, I still planned on having the reservoir connected to the input end. Would the plugged-output end mix with that extra fluid from the reservoir to help keep the temperature down? You said plugging it "just dumps it back to the suction side, so its circulating the little fluid thats in it and making it hotter and hotter." But I'm reading that as if both ends of the pump are plugged and so there'd be barely any fluid.

But what if only the output is plugged, and the input has access to more fluid from the reservoir? If the plugged output pressure "just dumps it back to the suction side," would having the input be connected to the reservoir be low pressure on that end? I don't know if the check valve you mentioned decreases the pressure when there is backpressure like that. Or maybe you meant the check valve would only circulate the fluid currently in the pump even if the input is connected to the reservoir, which would mean there's no point in connecting the pump input to the reservoir if the pump output is plugged since the pump would never open the check valve to have access to the reservoir.

 

[JLTD]

3 options I can think of:

replace the pump with an idler wheel to support the serpentine belt

if possible, reroute the serpentine without the PS pump (requires shorter serpentine)

put the outflow hose to the inflow of the pump as you mentioned.

 

[Astro14]

The output line on your pump is metal and runs across the intake manifold. It would be easy to cut that line, put on a bit of hose, and route that hose back to the reservoir return. That will keep the pump from blowing up. By the way, Pentosin CHF-202 is specified. Some manuals listed ATF, which is incorrect and will cause rack problems, including leaks.

But, I have to ask.

Why?

What are you gaining from disconnecting the power steering on this car?

 

[Ifixyawata]

Originally Posted by Astro14
The output line on your pump is metal and runs across the intake manifold. It would be easy to cut that line, put on a bit of hose, and route that hose back to the reservoir return.

But, I have to ask.

Why?

What are you gaining from disconnecting the power steering on this car?


Maybe the engine is going into something else and OP wants to keep the belt drive the same as there was probably never a no-PS option for the motor.

 

[Astro14]

Every single one of those motors has a PS pump. And the way that the serpentine belt is routed, you need the PS pump or you lose contact with the alternator pulley - the belt would just graze it. There is no good alternative for routing.

But, since this is a Volvo motor, and it's not normally used in anything but a Volvo, wagon, sedan, or CUV, I'm wondering what problem he's trying to solve by bypassing the rack.

The rack on the cars from which this motor came (P2 chassis) is a PITA to remove. Requires lowering subframe. And many of the racks were killed by ignorant owners who used the wrong fluid in the PS system.

So, back to my question, why bypass the power steering on a regular car? What is he trying to fix?

 

[Ifixyawata]

Originally Posted by Astro14
Every single one of those motors has a PS pump. And the way that the serpentine belt is routed, you need the PS pump or you lose contact with the alternator pulley - the belt would just graze it. There is no good alternative for routing.

But, since this is a Volvo motor, and it's not normally used in anything but a Volvo, wagon, sedan, or CUV, I'm wondering what problem he's trying to solve by bypassing the rack.

The rack on the cars from which this motor came (P2 chassis) is a PITA to remove. Requires lowering subframe. And many of the racks were killed by ignorant owners who used the wrong fluid in the PS system.

So, back to my question, why bypass the power steering on a regular car? What is he trying to fix?


I guess I didn't realize he was for sure keeping the engine in the car... rail buggy or something was my first thought, LOL.

 

[maxdustington]

Originally Posted by DejaVue
I've also heard of people taking pumps apart and removing the vanes or similar from the internals, so the pulley still spins, but the fluid inside the pump isn't being pumped at all. I'd rather just screw a plug in where the output line was though, if the high pressure won't hurt it.
You're going to have to gut the pump, or fabricate a custom idler. Why are you concerned about damaging the pump if you are disabling the PS?

 

[Colt45ws]

Originally Posted by DejaVue
I forgot to ask about that option, of looping it to the reservoir. The concern on that one is can the plastic factory reservoir handle the pressure the output line is sending into it? Normally, the reservoir is fed from the fluid exiting the power steering rack, at (from as far as I know) a much lower pressure compared to the pump's output pressure. You said looping it to the reservoir would circulate the fluid with no head pressure, but I don't know enough about power steering pumps to understand why the fluid coming from the reservoir wouldn't be at the same high pressure as the fluid being pumped into the reservoir since there's no power steering rack to reduce the pressure in the loop.

Even if I plugged the output end of the pump, I still planned on having the reservoir connected to the input end. Would the plugged-output end mix with that extra fluid from the reservoir to help keep the temperature down? You said plugging it "just dumps it back to the suction side, so its circulating the little fluid thats in it and making it hotter and hotter." But I'm reading that as if both ends of the pump are plugged and so there'd be barely any fluid.

But what if only the output is plugged, and the input has access to more fluid from the reservoir? If the plugged output pressure "just dumps it back to the suction side," would having the input be connected to the reservoir be low pressure on that end? I don't know if the check valve you mentioned decreases the pressure when there is backpressure like that. Or maybe you meant the check valve would only circulate the fluid currently in the pump even if the input is connected to the reservoir, which would mean there's no point in connecting the pump input to the reservoir if the pump output is plugged since the pump would never open the check valve to have access to the reservoir.

Because pressure is the result of flow trying to go through a restriction. The pump pushes out X ccs per rev and so if there is a restriction somewhere then it will still try to force that amount of fluid through so the pressure will rise until the bypass opens. In a PS system that restriction is in the PS rack or box. The hose coming out of the pump essentially shows no restriction.
Think of it like a open garden hose just drooling on the driveway, but if you put your finger over the end suddenly the pressure rises and you can spray your plants now.

 

[dlundblad]

Originally Posted by Astro14


But, I have to ask.

Why?

What are you gaining from disconnecting the power steering on this car?


Apparently the lines on these are notorious for rusting out. It was on Matthew's site (I think?) where a guy made and replaced his hard lines rather than tossing the perfectly functional rack. Better than buying Volvo OE for $900+ and certainly better than an A1 Cardone. I looked at hers when I did the motor mounts a while back and these seemed fine, but I sprayed them with an Amsoil undercoating anyways.

 

[dlundblad]

I would personally park the car until whatever it is gets repaired.

I'd have no faith in a temporary fix on a hydraulic system.

 

[Astro14]

Yeah, the lines on this do rust out. And as previously posted, the rack is a PITA to replace. Not cheap, either.

So, I wonder if the OP is going to try and drive an older Volvo without PS.

That's the only logical reason for his question.

And it's why I asked mine.



dlundblad - I've also flushed the PS system with CHF 202 and put a Magnefine in the PS return line to keep the rack and pump happy. At 237,000 miles on the XC, and about 190,000 on the T5, the original rack and pump are fine.

If he needs a pump, I would go with an Erie Vovo used unti for about $70. New, they're $400.

For a rack, well, there aren't a lot of good options. OE, as you say, is $1,000. I dislike the quality on A1 Cardone, and on a rack that requires dropping the subframe to replace, a lifetime warranty is worthless. A new part would be my recommendation, unless, ZF rebuilds them directly. Edit: I see that there's a core even on Volvo OEM. so, they're rebuilds, too.

Hmm...

 

[SnowDrifter]

If you need to do that you can just connect the pressure line to the return line

Though the idea solution would be to remove the pump altogether and replace it with an idler pulley

 

[DejaVue]

Originally Posted by maxdustington
Why are you concerned about damaging the pump if you are disabling the PS?

Because the pump needs to be there for the serpentine belt, and I assume the pump bearing will be destroyed quickly if it doesn't have fluid to lubricate it. I was all set to just plug the lines or loop them, but then wondered if the high pressure the pump normally outputs would be a problem in some way.

And I've never seen an aftermarket pulley available to replace the pump, like is often available for more popular to mod cars, so trying to put just a pulley there would be more custom than just plugging or looping the lines. Gutting the pump should work to reduce the fluid pressure, but taking a Volvo one apart is apparently a pain, and if the lines can be plugged or looped without gutting it, that should be a lot easier.

 

[Astro14]

You've not answered the question: why disconnect the power steering?

To what end?

What problem are you trying to solve with this engine?

You can loop it. Easy.

But in what application will this be beneficial?

 

[DejaVue]

Originally Posted by Astro14

The rack on the cars from which this motor came (P2 chassis) is a PITA to remove. Requires lowering subframe. And many of the racks were killed by ignorant owners who used the wrong fluid in the PS system.

So, back to my question, why bypass the power steering on a regular car?

Originally Posted by Astro14
as previously posted, the rack is a PITA to replace. Not cheap, either.
So, I wonder if the OP is going to try and drive an older Volvo without PS.

You got it.

The rack has a big leak, replacing it is either expensive, a PITA, or both. Rebuilt racks have many poor reviews. Used racks are in unknown condition, and the racks aren't known for their durability even when brand-new.

 

[Rand]

Not sure how old you are but have you ever tried driving a car with power steering disabled?

Its much worse than an old manual power steering rack.

The power steering rack usually doesnt have near the ratio that a manual one would. Could be a safety hazard.

 

[Astro14]

I understand the situation better, now. Thanks.

I've not tried bypassing the PS system in this car, but it should be a piece of cake. The O.D. Of the pressure line is about the same as the return hose I.D. So, run a piece of hose between the pressure line and the reservoir return. It should be fine.

I'm curious how the system will feel in driving. I've got a non PS car. It was designed as such.

And it's not easy...

You may well find that fixing this is preferable.

Please keep us posted on your findings.

 

[DoubleWasp]

On twin engine boats using GM engines and power steering pumps, only one engine drives the power steering ram. The other engine's power steering pump is simply routed back to itself. Will operate fine that way forever.

Routing it back on itself will have no consequences where the pump is concerned.

How will the car drive? Different story. I knew a lot of people back in the day who pulled out their power steering pumps on RX-7s to drive them as manual racks with good results, but there are cars out there that use power steering pressure to center the wheel. Drive might be floppy without having power steering pressure.