New PS Pump Whining...what am I missing here?

[Rogue]

So I installed my new PS pump yesterday, a reman ACDelco pump, since I was doing the EVO delete anyway and my old one was getting pretty leaky. Replaced two of the lines too since I was there. This new one, though, is whining. I've never done this before, but is that normal? I did the bleeding procedure and all yet it's still doing it. I've read online, in general, it goes away in 3 days to a full week, but what's been everyone else's experience when doing this on the GMT400s?

 

[Bob L]

Does the fluid look foamy when you first shut the truck off? That would mean it still has air in the system. Start it up and crank the wheel lock to lock a few times ,it may take some driving but it should go away if the fluid level is up.

 

[Rogue]

Does the fluid look foamy when you first shut the truck off? That would mean it still has air in the system. Start it up and crank the wheel lock to lock a few times ,it may take some driving but it should go away if the fluid level is up.

I drove it about 2 miles this morning and it didn't look foamy. I'm going to drive it a bit this afternoon on the interstate and I'll see how it handles and if the noise is still there after I get back home tonight.

 

[Rogue]

After driving it a bit this afternoon (about 20 miles between interstate and highway) the pump is still whining, but less. And when I did check the fluid right after I shut it off when I got home, there were a few bubbles.

 

[someotherguy]

Either the rebuilt pump is low quality, which is likely...or you bled it incorrectly, which is also likely. That's not an insult against you, just saying most people do it wrong. Filling it up then starting the engine and turning the wheel lock to lock (even with wheels off the ground) is loading the pump while there's still air in the system, causing damage immediately.

Per GM, you fill the reservoir, start the engine for just a moment, shut it off. Check level and fill again if needed, then start, shut off, fill as needed, etc. Once it finally no longer drops level when you start it up, then with the wheels off the ground, turn it from lock to lock, check level, and fill some more as needed. This runs and loads the pump the absolute least amount of time possible until you've got all the air out of the system.

Richard

 

[jkeaton]

I replaced mine with a rebuilt one and it has wined since day one. I just figured its par for the course. I tell everyone its a supercharger.

 

[mistaake]

I had two bad reman ACDelco gearboxes. Not too pleased with their rebuilt steering stuff :/ honestly the generic stuff from O'Reilly is probably the same or better!

 

[Rogue]

Either the rebuilt pump is low quality, which is likely...or you bled it incorrectly, which is also likely. That's not an insult against you, just saying most people do it wrong. Filling it up then starting the engine and turning the wheel lock to lock (even with wheels off the ground) is loading the pump while there's still air in the system, causing damage immediately.

Per GM, you fill the reservoir, start the engine for just a moment, shut it off. Check level and fill again if needed, then start, shut off, fill as needed, etc. Once it finally no longer drops level when you start it up, then with the wheels off the ground, turn it from lock to lock, check level, and fill some more as needed. This runs and loads the pump the absolute least amount of time possible until you've got all the air out of the system.

Richard

That's the procedure I used, except I didn't go to full lock, I stopped just before it since my Haynes manual said to do that. I've read elsewhere online that with vehicle PS pumps in general, the whining goes away after three days to a week....not sure it's true since I don't believe everything on the internet. Any truth to that?

 

[someotherguy]

Yeah, going to full lock just puts the pump in bypass anyway so it's pointless to go literally all the way and hold it there. It's good to know a Haynes manual actually got something right (close/same as manufacturer recommendations) as usually I don't trust them for anything.

My guess would be the pump sucks, which is pretty common. But sure, give it some time and see if it quiets up any.

Richard

 

[jollyjerry]

That's the procedure I used, except I didn't go to full lock, I stopped just before it since my Haynes manual said to do that. I've read elsewhere online that with vehicle PS pumps in general, the whining goes away after three days to a week....not sure it's true since I don't believe everything on the internet. Any truth to that?

To avoid loading the pump after installing, I filled the resevoir, lifted it off the ground, and turned lock to lock a few times because I figured this would get some air bubbles out. Thanks for sharing the factory service steps Richard, will keep that in mind in the future.