Not sure if this is the right forum, but I have a power steering fluid cavitation issue that cannot seem to be fixed. I’ve had everything replaced in my entire power steering system (reservoir, pump, all hoses, steering rack, etc) except the PS cooler yet i’m still getting cavitation which is creating grinding sounds from the pump. Its usually the loudest on a cold start then gets better throughout the drive.

The issue first came around the day after a track day at Willow Springs and thats when i slowly started replacing things. The pumps been replaced 4 times, and the cooler was tested with 1000psi of air to make sure there’s now clogs or holes. Does anyone have any idea what could be going on? I brought it to Infiniti before replacing everything, and their diagnosis was to replace everything (of course), which I did by a VQ knowledgable mechanic who owned a G37 himself. He gave up after trying everything he could think of to fix this problem.

Someone please help. Shoot anything you may have because i’m really stretching for ideas here.

 

What year car do you have?
Transmission type?
Sport/base?
Type of fluid?
Events on when it happens? start up/all the time/over time/upon abuse.

 

Hey thanks for reaching out. Sorry I probably should have said all this stuff.

2010 G coupe sport m/t

fluid: not sure what was in there to start, but my mechanic has used Redline Full Synthetic, Idemitsu, and redline D4. All acted the same.

It happened first the day after a track day, then never went away after. Always on cold starts and becomes more subtle throughout drive. After rack/pump/HP hoses were replaced, it went away for like 2 weeks. Comes back immediately after standard fluid flush. You can hear the sound standing in neutral and just revving. Becomes louder if you add steering input in either direction. The mechanic said the noise is most definitely coming from PS pump.

lmk if there’s any other info I should provide

 

I take it the power steering pump it has is the Sport's pump (nut in the middle)

These pumps are finicky with fluid, only Nissan ATF should be used. It's possible that the pump got messed up when with the fluid he originally used.

A new pump and fresh Nissan ATF should be used. Because it starts whining upon starts means worn pump/incorrect fluid. The good news on that is that the sport pump is the same for Titan, Armada, QX56.
I have that pump in my sport sedan and it can be found for $60 so it shouldn't be so expensive to change this again. ( pulley and pump bracket need to be from the G37)

It would also require a full flush again, most folks who used other fluids have done so after they ran Nissan fluid.

 

Thats interesting because I’ve heard of people using various fluids. My mechanic had a drift G37 with stock PS system and used the redline fluid with no issues. But I supposed its worth a shot to change the fluid out. I just had the pump literally replaced again yesterday for free and the Redline Synthetic PSF was put in. Should i just try switching to the Nissan ATF fluid and hope that the pump isn’t damaged?

 

That's very weird, ou should still try it for the sake of the process of elimination however you and your friend are right it should be able to handle red line just fine. It wouldn't hurt to try switching over however fluid cavitation/whine should normally happen after warm up other than the initial whine as air leaves the system.

Whats the brand of the pump? Can you post a picture?

 

Ok i took some pictures the best I could lol. According to my mechanic this isn’t remanufactured either. The tag on the pump says “PSP0013 JAPAN”. I forget if this is the 4th or 5th pump replacement attempt.

 

Looks to be the right pump.
Here's a thread I made with pictures comparing the journey vs the sports G37 pump and in the bottom ones comparing the OEM sports vs the titan pump.
Titan is what I'm running and it feels exactly the same. I seriously doubt all of those pumps keep failing.
Then confirmation of flow through the cooler should remove it from being a fault.
The racks are the same, I'm running a Journey rack in my sport (same numbers on the rack)

Doubt the PSW is causing this because it's job is to inform the ECM, the pump has a mechanical relief valve
A weird possibility could be the rack is causing this issue by t's internally leaking/bypassing the pressurized fluid into the return.

For further diag, you should switch the feed hose to the pump with a temporary clear one, I suspect the filter inside the reservoir is saturated and it's causing the fluid not to flow properly into the pump creating pockets of vacuum. These pockets will introduce air into the pump causing the whine and cavitation. With a clear hose you should be able to see these pockets or at least if the fluid is moving correctly into the pump. A type of reservoir bypass/homemade reservoir to remove this possibility out of the equation

 

ok I see what you’re saying, thats a good idea. The reservoir is brand new though, so I doubt the filter would be saturated. However I can’t remember where my mechanic said he got the filter from. I think it wasn’t oem but it was received from the same suppliers that make the oem? I can post some pictures of it when I get back to my car.

 

The filter for the power steering should be inside of the reservoir, there should not be a filter in this system at all FYI.
A brand new/cleaned reservoir should take care of this. A clear hose will let you know if how the fluid is flowing into the pump.

 

Yeah so the filter is brand new then since the reservoir is new. Here is a picture of the reservoir if it matters. If I don’t get any ideas then maybe i’ll do the clear tubing thing. I just haven’t actually worked on any of this steering system myself yet so i’m hesitant to start messing with things right now. But if I’m stuck with no other ideas then I’ll give it a shot. I was thinking of trying to find a different infiniti dealership and ask for their lead mechanic (if they have one) to do another PS system diagnosis. I was gona say that if they’re not gona talk to me about whats going on and intuitively look at my system rather than just telling me to replace everything, then i’m not interested lol.

 

You might want to have a look at the owner's manual for the required power steering fluid.
All the fluids listed in this thread are not compatible.

 

ok yeah I think I’m gona try swapping out to the nissan fluid asap, since my pump is only 2 days old right now. Hopefully I didn’t damage it if the fluid is the issue

 

Good advice in here, but also make sure you’re properly priming the pump, as dry running/cavitation on a new pump can cause damage. The best way I’ve found is to fill the reservoir to the top, then start the car for 1 second, just enough to pull the fluid in, then fill again and do the same, this way you’re not dry running the pump and foaming the fluid. Last thing I would say is kinda obvious, and it looks like you have a good tech working on your car judging by how clean everything is in your photos after several pump replacements, lol. But make sure you have the proper length belt and a good belt tensioner and it’s not allowing slip on that pulley, slip will cause fluid backup in the rack and cavitation.

 

Though minimal noises occur upon pump change I've found the best practice is to install everything including fluid and before the belt is installed rotate the pump towards its normal rotation by hand. A couple of quick turns by hand will get most of the air out making start ups almost fully "wet"