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GearheadBrown, ASE Certified Technician
Category: Car
Satisfied Customers: 68
Experience:  10 Years various auto repair and diagnosis. Nissan Specialist technician. ASE Master certified.
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Tacoma: My 1997 Tacoma has a grinding noise coming from the

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My 1997 Tacoma has a grinding noise coming from the power steering pump. I replaced the pump and still the intermittent noise is there. It sometimes goes away when the engine is warm or if I shut the warm engine off and restart it. There are no visible leaks. The pump seems to be straining for some reason. I suspect the vacuum driven dump valve located on the high pressure discharge line of the pump. Any Ideas?
When you replaced the pump, did you flush the lines and rack out before assembly and use? I ask because there could have been contaminants in the system from the old pump, which may have damaged the new pump once you ran the vehicle again.

Of course sometimes you just get a noisy pump, which as long as your power assist is working, will not be an issue.

In any case, I have had great luck getting noisy power steering pumps to become quiet by adding half a tube of friction modifier to the reservoir. (Made for limited slip differentials)

Good luck, let me know if you need any further assistance!
Customer: replied 3 years ago.

why would the loud noise ( like the pump is really straining) be intermittent and completely stop at times? It comes and goes and is especially dependent on the engine being warm or the temp outside is warm?

If it is a different sound than what you hear at the steering lock positions, then it could be a bearing or gear inside the pump that is not in the best of conditions.

Did you flush the lines before installing the new pump?

Customer: replied 3 years ago.

No, I did not flush the lines. Can I flush them now and add new ATF or is the damage a done deal? What is the best way to flush the lines? Do I have to disconnect one of the return lines to the pump to do that? Will it drain by gravity or does it need to be pumped out somehow?

You can try flushing it out, but in my experience Power Steering pumps tend to be very sensitive to any contaminants.

I always use compressed air to flush out the lines. You don't have to worry about every last drop, but it get's most fluid out. You only need about 40-50 psi, and wrap a rag around the hose where you connect your air nozzle to to keep from making a mess.

I would try flushing out the system, then reconnect the current pump.

However, be careful how you do the first start up, as the reservoir will empty out a couple times as it fills the rest of the system. I usually fill the reservoir, and start the car, and immediately shut it off. Refill the reservoir, and repeat until it holds the level. This will prevent you from running the pump dry and causing damage as well.

As I said before, you can also try adding some friction modifier to the fluid, it should help with noise some. Otherwise you may end up having to replace the pump again.
Customer: replied 3 years ago.

The compressed air trick should work. Can I just put an extension tube on the low pressure return line coming back into the pump to capture the blown out fluid? Still it has me flummoxed as to why it will be quiet at times an make no additional noise at all and then start growling again...hmmmm

The tube will work fine for catching the old fluid.

As far as the intermittent noise, it is hard to say exactly what inside the pump is causing it. PS pumps are usually replaced as a unit rather than being rebuilt.
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