M998 Power Steering Fluid Reservoir Types

[WhoMe08721]

Hey guy,
What is the Difference in power steering fluid reservoirs. My M998 6.5 n/a has the power steering fluid reservoir located on the power steering pump. But then I see truck with the round reservoir located on top of the engine.

 

[NDT]

Yours with the attached reservoir is the GM Saginaw type. The pancake reservoir feeds this pump through a hose. There are two versions of this pump, lotsa pressure and even more pressure.

 

[Coug]

Pre 196900 and post 196900 serial number setups.

There is also a difference in belt routing and an additional idler pulley for the post 196900 serial number setups with the remote reservoir, along with a different support bracket for the rear of the alternator.

 

[Mogman]

Yours is much cheaper to replace the pump itself, swapping in your original reservoir, that pump was used on just about every GM vehicle from the mid 80s to the late 2000s at least, it is the metric version.
I compared pressure/flow on a Cordone replacement (set up with the max pressure/flow control valve) to a good working OEM and there was no difference.
In fact the 2008 LMM Duramax in my DuraVee has the same pump.
I also replaced a 6.2L that had the Saginaw style with a 6.5L GEP turbo engine that had the higher pressure style remote reservoir pump and did not feel any real difference.
I would suspect the later version would be a little more durable and would suggest to anyone that has a hydraulic winch to add a better PS cooler.
On my Dmax conversion because the engine oil cooler is integral to the engine I used the engine oil cooler for the transmission and the transmission cooler for the steering

 

[Thunderbirds]

Yours is much cheaper to replace the pump itself, swapping in your original reservoir, that pump was used on just about every GM vehicle from the mid 80s to the late 2000s at least, it is the metric version.
I compared pressure/flow on a Cordone replacement (set up with the max pressure/flow control valve) to a good working OEM and there was no difference.
In fact the 2008 LMM Duramax in my DuraVee has the same pump.
I also replaced a 6.2L that had the Saginaw style with a 6.5L GEP turbo engine that had the higher pressure style remote reservoir pump and did not feel any real difference.
I would suspect the later version would be a little more durable and would suggest to anyone that has a hydraulic winch to add a better PS cooler.
On my Dmax conversion because the engine oil cooler is integral to the engine I used the engine oil cooler for the transmission and the transmission cooler for the steering

I actually just got done with my replacement yesterday evening. It works great, but still bleeding it, over and over again.

I only have one hint, if you get the aftermarket pump, reuse the relief valve cartridge (Item 10, TM9-2320-280-24P, page 176-1) into the new pump. I've read a few times that may be the difference between the aftermarket and the OEM pumps for the HMMWV. Here is the different cartridges in my case. The left one is the aftermarket, the right one is what was installed in my M1123.



The pumps are very identical other than that.



This one I picked up at the local NAPA, for around $82.99. Napa part number was PS 385139 IIRC. The website has dozens other ones, but this is what they had in stock that day. It worked great for me.

Other than that take your time removing and installing, the reservoir is not made of very thick metal and can be distorted if handled too rough. But it is a good fit, no leaks. Oh, one thing, the bolts holding the pump into the reservoir on mt truck were metric 10mm x 1.5. The pump from NAPA were 3/8 x 16 SAE.



Have fun with it...

 

[Mogman]

I actually just got done with my replacement yesterday evening. It works great, but still bleeding it, over and over again.

I only have one hint, if you get the aftermarket pump, reuse the relief valve cartridge (Item 10, TM9-2320-280-24P, page 176-1) into the new pump. I've read a few times that may be the difference between the aftermarket and the OEM pumps for the HMMWV. Here is the different cartridges in my case. The left one is the aftermarket, the right one is what was installed in my M1123.

View attachment 954905

The pumps are very identical other than that.

View attachment 954906

This one I picked up at the local NAPA, for around $82.99. Napa part number was PS 385139 IIRC. The website has dozens other ones, but this is what they had in stock that day. It worked great for me.

Other than that take your time removing and installing, the reservoir is not made of very thick metal and can be distorted if handled too rough. But it is a good fit, no leaks. Oh, one thing, the bolts holding the pump into the reservoir on mt truck were metric 10mm x 1.5. The pump from NAPA were 3/8 x 16 SAE.

View attachment 954907

Have fun with it...

That is the pressure/flow control valve I was speaking of, using the original one is a good idea, there is also an aftermarket "kit" that allows adjustment of the pressure with shims.