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Discussion Starter · #1 ·
I have an issue with my 2005 2500HD Duramax where the power steering and brakes don't work for the first few seconds after starting the truck. After a few seconds they start to work normally. I have replaced the power steering pump, all power steering hoses, and the hydro boost unit in the past six months with no change in the symptom. Has anyone had a similar issue? If so what was the fix? Thanks.
 

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2003 GMC Sierra 2500 HD Crew
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My 03 has done this a few times. Most often when it's cold so I blamed cold fluid. I only notice it turning around in the driveway and most often I notice the steering instead of the brakes.
 

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Discussion Starter · #3 ·
My 03 has done this a few times. Most often when it's cold so I blamed cold fluid. I only notice it turning around in the driveway and most often I notice the steering instead of the brakes.
Thanks. This issue started when the weather turned colder for me. I have changed the power steering fluid a couple of times now so I am not sure if it is fluid related or not.
 

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The good news is you've got lots of new parts now :) What kind of fluid are you using? I know my log splitter says not to use standard hydraulic fluid when the weather is below freezing, it wants Dex/Merc ATF.

I suspect the vanes in the pump are a little sticky because of the cold fluid. It takes a few seconds for them to start moving and sliding after the pump starts turning. And the system doesn't normally store pressure in the lines after the truck shuts down (there is pressure in the hydroboost accumulator for braking)
 

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Discussion Starter · #5 ·
The good news is you've got lots of new parts now :) What kind of fluid are you using? I know my log splitter says not to use standard hydraulic fluid when the weather is below freezing, it wants Dex/Merc ATF.

I suspect the vanes in the pump are a little sticky because of the cold fluid. It takes a few seconds for them to start moving and sliding after the pump starts turning. And the system doesn't normally store pressure in the lines after the truck shuts down (there is pressure in the hydroboost accumulator for braking)
I’m using power steering fluid, GM spec. Same fluid I’ve used since the truck was new. It has been changed recently due to all of the work on the system.
 

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I'd still point towards sticky vanes in the pump - they require centrifugal force from the pump hub spinning to make contact with the pump housing/case. Could try to thin the fluid out a bit, take an ounce or two of the fluid out and replace it with ATF, and see if that helps.
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If it's only a few seconds and only when cold, I wouldn't fool with it. But it may bug you and you may want it fixed. Your truck, your money, your choice.
 
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