My truck isnt liking this really cold weather. Yesterday evening I was at a friends place and when I was going to return home I started my truck and it immediately blew the back out of the power steering pump. I drove home without power steering or power assist for the brakes. I am currently waiting for a used pump but I have a reman on order also. This will be the second pump. My neighbour also has a GMC 2500 and had to replace the power steering pump also.
Actually the pump itself is aluminum and the snap ring and cover are just slightly discoloured from rust, I can rub it off. This used pump actually lasted longer than the original pump. The shaft broke in the first one, probably a defect from new but l wasnt the original owner so no warranty. It was -22 when I started the truck. It started immediately, it really didnt crank over at all. The cam sensor must have been right at the trigger point. I think that in the cold the fluid couldnt get out of the pump fast enough and the pressure built up really quickly and burst the pump.
In the case of aluminum and steel coming in contact and being exposed to water, air, and heat (and road salt to help speed it up), there will be galvanic corrosion between the two materials, with the aluminum giving up electrons to the steel. This results in the aluminum corroding while the steel remains in relatively rust-free condition.
From looking at your pics, it's possible that it is corrosion-related, as 67Poncho says. If a galvanic reaction occurred between the steel snap ring and the aluminum housing, the pressure from the corroding aluminum (from the volume increase of the oxidized product over the original aluminum alloy) could increase the stresses on the housing where the snap ring is holding the backing plate. A higher-than-normal pressure due to the higher viscosity of the cold fluid could help to put it over its failure point, breaking the housing where it did. If there was significant material lost from the housing at the snap ring retaining area, this could further weaken the housing.
Just a theory, as it's hard to tell by the photos. if you remove the snap ring and plate, there would be white-ish corrosion built-up in the areas where the housing touched the steel (and where water and air could get at it), and likely evidence of material loss from the aluminum in the form of a rough surface in the groove.
Or, I could be completely wrong, just having fun guessing at what might be the cause.
When I was looking for a replacement pump I tried to find a reman pump from the jobber I use. He said that there were no reman or new available and he didnt have any idea when he could get one. The dealer showed one in stock in a warehouse but didnt know when he could get it so I think it must have been in the states. The auto wrecker didnt have one but on his parts lookup he said there were two in Ontario so one will be here Tuesday. It seems to me that these power steering pumps must have problems, thats why I ordered a new one also. And yes its a 6.0 litre pump from my 2015 GMC 2500HD.
I posted here somewhere about changing the ps pump on my 02 Duramax. Replaced it with with a Delco reman and it didnt work. Talked to the local garage guy that works on these trucks and he said he got two bad Delco remans so he bought new GM. Thats what I did. I had to replace the original because the steel return line nipple rusted out.
