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Power Steering Pump / Vacuum Pump Conversion

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broken vacuum line

Delphi 680 steering box

petersonj

TDR MEMBER
Power Steering Pump / Vacuum Pump Conversion

This project (courtesy of @mace on the Moparman1973 site) replaces the OEM gear driven vacuum pump with an electric remote mounted vacuum pump and replaces the piggy-backed OEM power steering pump with a direct mount power steering pump accompanied with a remote reservoir. The replacement power steering pump is a vane pump with flow rated at 3.4 GPM and an operating pressure of 1,450 psi. Prior to starting this project, I performed the APPS throttle assembly relocation. Here’s that link:

https://www.turbodieselregister.com/threads/removing-the-complete-apps-assembly-from-engine.275636/

My purpose for doing this project was for a few reasons:

* I wanted to eliminate the OEM gear driven vacuum pump (no more potential oil leaks or difficult access).
* I wanted an accessible location for the power steering pump reservoir.
* I wanted to use the space where the APPS assembly used to be for the remote power steering reservoir location.
* I replaced my old direct-mount PacBrake exhaust brake (vacuum operated) with an upgraded in-line PRXB PacBrake (compressed air-operated) exhaust brake. This exhaust brake performs much better at low rpms.

Here is the direct drive power steering pump that I installed.

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I started the project by finding the specific location for the new power steering reservoir, which was going to be right where the APPS assembly used to be. Then I built a mounting bracket for the reservoir (shown below). The first part of the bracket assembly is designed to let the weight of the reservoir and the contained fluid rest into the V slot.

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In the photo above, note the welded nut where the tab on the top of the reservoir is screwed into the bracket (a little out of focus in the photo).

In the photos below, more brackets are added to fasten the unit to the engine.

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Below is the new location for the reservoir in the engine compartment - lots of space available for mounting with the removal of the APPS mounting assembly.

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The time and effort spent on this project (and the previous APPS relocate project) has been very worthwhile. Much engine space has been freed up and the power steering reservoir is right where it should be for easy fluid check / fill. The reservoir is like the brake master cylinder reservoir – you can see the fluid level through the reservoir.

An unexpected benefit was that this direct mount power steering pump outperforms any previous power steering pump that has been on this truck. There is no more stopping / stalling of the steering wheel when the power steering is under high demand, such as when maneuvering in tight spaces, steering from stop to stop with little forward or backward movement of the truck.

Also, less steering effort is required in just normal driving going into curves and when operating in parking lots. I am not sure why this pump outperforms the other pumps since the specs are the same, but it does. Mace observed the same results with his truck, as well.

John
 
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I looked at putting a HD p/s pump like the ones used on our buses on my 12-valve. The smallest pump in terms of pressure and volume I found was WELL over the specs on our OE system. I was afraid of damaging the gear with the excessive pressures.
 
I was afraid of damaging the gear with the excessive pressures.

I hear you - I wouldn't want to use that pump, either.

Here is the direct-mount pump that I purchased.

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And here is the Borgeson pump from Geno's.

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Note that the flows and pressures are virtually the same, but the direct gear drive pump definitely outperforms the others. For about a 100,000 miles, I had a Borgeson pump installed, but it didn't perform any better than the OEM pump.

I think there is a better quality flow control / relief valve in the direct gear drive pump. Just my opinion, though.

- John
 
What vacuum pump did you go with? I have an electric on my Ford conversion. The power steering pump is similar to what you posted and is driven off the rear of the air compressor.
 
What vacuum pump did you go with?

I went with Standard Motor Products VCP112. It was used on Ford vehicles, I think. The pump is noisy, but can't be heard with the engine running. It does the job well for operating the HVAC system and the 4WD CAD unit without using a vacuum reservoir. It is not adequate for the use of a vacuum operated exhaust brake.

- John

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