power steering pump noise with vibrating brake pedal

[triple_ratrider]

Did my best to search the forums and archive and couldn't find anything like what just started with my '98 AWD. Everything was totally normal until I parked last night after about a 20 minute drive. Turned the wheels into the curb, set the brake and put it in park - immediatedly heard a noise like someone putting a rubber mallet into a fan, steering wheel and brake pedal both vibrating in time to the noise. Noise and vibration increase with engine speed (think playing card in your bike spokes, but muffled a bit).

Power steering and brakes both work as they should. Noise gets louder when you accelerate, turn the steering wheel or hit the brakes. Once up to about 25 mph, the condition settles a bit, but doesn't go away. As I brake to a stop, the vibration of the brake pedal decreases in speed but increases overall movement (amplitude versus frequency). Noise does not stop so long as the engine is running.

My first thought was maybe the PS fluid was low, but it only took a 1/4 cup or less to bring it up to full and made no difference at all.

There are some sparklies in the PD fluid and it smells a bit burnt. I can also see the big hose from the PS reservoir to the PS pump is vibrating pretty good when the engine is at idle.

The only other thing to add is that my wife thought she heard a loud pop the other day when she turned the wheel for a tight turn. She thought it sounded alot like a CV joint going, but only one pop. Not sure if that is related - the idler arms are toast and replacements are on hand to change them out too.

Anyone have something like this or have advice on a diagnosis? This is our only car and Mrs. Ratrider isn't too keen on walking to the grocery store.

Judging by how I can barely get my eyes on the PS Pump, it's not going to be fun to swap out. Is there something else that this could be?

Thanks!

Ben

[Matrixx]

Hi triple_ratrider

I read what you mentioned above and it sounds like a broken power steering pump bracket or a sheered pump shaft. It looks a lot worse than it really is to access the pump. Just remove the intake filter, box and tube, then it's just 9 retaining screws to remove the top radiator shroud.

If you just want to check the pump, then it may be easier to jack the van up, block the back wheels, then jack stand the front and you can access the pump area pretty easy from underneath to inspect it. If it needs to be removed,then you will need to access through the top as well. Hope this helps.

[astro355]

It will be a lot easier to access the power steering accessories from underneath the van, possibly while you are replacing the idler arms. Are any of the other systems on the serpentine belt assembly affected? Odd alternator charge? Have you tried adding more load like turning on the a/c?

[triple_ratrider]

Thanks for the replies -

I hadn't considered something as simple as a broken bracket. Power steering and brake boost are still working, so I don't think the shaft is sheared (yet?)

From reading other posts, it looks to me like normal failure mode for the PS pump is a sheared shaft. Is it also possible for one of the internal vanes of the pump to come apart and create the noise I'm getting?

I will try loading up the system and see if that makes any difference in the situation. At the moment all other systems seem to be OK. I would really love to find that it's actually some kind of belt or accessory problem, but I can't see any evidence of such yet.

I'll bum some garage space ASAP so that I can get the van in the air for a crawl around.

Initial look with a flashlight found two other things that I'm overjoyed about. 1) the oil cooler lines I replaced just two years ago are leaking AGAIN! BAH! That was simple job made stupid by the AWD. 2) the minor coolant seep at the rear intake manifold is dribbling all the way around to the front of the motor and mixing with the oil from the cooler lines and this delightful sauce is all over the front diff and steering rack.

This could get messy.

Will report back with more detail soon.

Thanks!

Ben

[triple_ratrider]

Tonight's update - inspection of the pump, pulley and bracket yield no signs of play - everything feels rock solid. With the motor running and a lovely assistant at the wheel, I watched as brakes and steering were applied. No Movement of the pump and no discernable effect other than the loud noise and vibration.

One thing I note is that from the outside of the car while listening at the engine, the sound includes a sort of chuffing, as of rapidly pulsing air (or fluid) being forced through something. The noise seems be coming from high up in the engine compartment rather than down by the PS Pump. Could just a trick of accoustics, but it makes me wonder.

Belt appears to be in good condition, all pulleys, idler and tensioner doing their things nice and smooth.

Loading up the system with AC, lights, fan, etc didn't seem to make any difference. However, the noise at idle (no brake or steering input) was almost gone with the engine cold (35 deg F outside) and after 10 minutes or so of running, it was quite a bit louder.

I made a recording of the noise - didn't really capture the full scope, but gives a good idea of what I'm talking about. PM with an email address if you'd be willing to give a listen. It's about 20 seconds, 850kb wav file.

Thanks!

Ben

[astro355]

Send it to [email protected] please.

[triple_ratrider]

file sent, thanks!

[AstroAustin]

I posted a little video on youtube so you can see as well as hear what's happening.

Ben

[astro355]

That video helps a ton. I would tell you you need a power steering pump. Anytime you put a load on it (either with the brakes or steering wheel), you can hear it stressing. Maybe its an internal balance issue with the pump, maybe part of the propeller is damaged, etc. I just don't think air being trapped in the system would cause that extreme of a condition.

[triple_ratrider]

Thank astro355!
So, looking at power steering pumps I see some come with the reservoir on the back of the pump, some don't. No biggie to swap BUT, I also see for a big bump in price I can get one that includes the "EVO Component". Looks like some kind of sensor/valve works with the steering/brake system, perhaps to regulate system pressure? Any idea if it's worth the extra $$ to get the one with EVO? I'll be checking my books today as well, but if you have input, I'd appreciate it. This is the kind of job I'd like to do only once, ever.

Thanks!
Ben

[astro355]

I would just get a stock replacement.

[triple_ratrider]

I got started on the PS Pump removal tonight. With help of handy-dandy pulley puller from O'Schucks I got started on the pulley. In the process of pulling the pulley, I couldn't help but notice that the pump spins smoothly with no noise at all when I turn it by hand. Slight resistance when I spin it several rotations in the pumping direction is about all that I get.

I traced the source of the hammering vibration noise - it is the PS fluid cooling loop that goes out under the front bumper. It sets up quite a racket as it vibrates against the plastic. If I grab the loop and hold it away from the plastic - I can pretty much stop the noise. At that point, all that's left is a throbbing brake pedal when it is engaged.

All this to say, I'm not convinced that the pump is the problem. Yes, something is up with the system - but I hate throwing money and time at a problem that I don't fully understand.

Is there a way to verify what's going on other than replacing parts until I get the right one? Could a problem with the ABS or brake booster also induce this kind of symptom?

Thanks!

Ben


PS - Lovely Assistant is hoping I give up on the Astro so she can get a Toyota Sienna instead...sigh

[Matrixx]

Hi triple_ratrider

Sorry for the delay, been under the weather lately. I agree with what Astro355 has suggested (replace the pump). Hmm, The vibrating loop is the result of something else causing the pulse. The only thing that can cause an imbalanced fluid pulse is the power steering pump. That PS cooling line is directly connected to the pump itself and nothing else. So theirs a good indicator right their.

Turning the pump shaft by hand only 2 or 3 revolutions per minute isn't going to tell much on how the pump performs under pressure or higher rpms under load conditions.

Is that an ABS light I see on in your dash in the upper left hand corner? If it is, is it on all the time or not? Please keep us updated, Thanks.

[astro355]

I can see the cooling line contacting the plastic trim making that noise but something is happening to make the cooling line move, like inconsistent line pressure.

[triple_ratrider]

Aha! Now we're making some coconut sounds!

I wasn't clear on the fluid path for the cooling loop - if it is only connected to the pump, then it makes more sense that the pressure problem is likely to be there.

No ABS light, the lights in the video are no seatbelt and parking brake set.

I wondered about pump speed not being enough by hand to matter. I was just hoping to find the pump was obviously bad. Probably still take it apart just to see what's in there.

Tonight it all comes out. Should have the hoses Friday and I can do the oil cooler lines while the pump is out. Should make it a little easier too.

Thanks for all the input!

Ben

[Matrixx]

Hi triple_ratrider

PLeeease do not take it apart. That is a can of worms you really don't want to open (for me anyways, been their done that and I didn't like it one bit). If you can buy a complete unit, then that's my strongest suggestion here. Your going to have your hands full enough getting the pulley back on the pump. Please keep us updated, thanks.

[astro355]

He can take it apart as long as he doesn't expect to get it back together. That is not a crack at your mechanical abilities, its just a real PITA to R&R a power steering pump.

[triple_ratrider]

Pump is out - whee fun.

Would be less than half the task on a 2WD. Why must the front diff be EXACTLY in the wrong spot? Oh well.

Lots of metallic junk in the old ps fluid, no big broken stuff - more like sub mm flakes of shiny metal.

Nobody has a complete pump in stock - only the kind you have to swap the reservoir, flow valve and EVO componant (electronic variable orifice). For the $54 and right here now, I bought one at Schucks (Cardone lifetime warranty, if I bring the defective pump back). Of course, that's the same pump Rock Auto sells for $35...

Seeing the amount of stuff stuck in the screen on the flow valve, I'm second guessing this. Have to wait til Monday for the new hoses anyway - should I pop for the $150 unit that comes fully assembled with new flow valve, EVO and res? Torn between the impatient cheap guy and the cautious don't ever want to do THIS again. Somewhat peeved that the unit that requires a reservoir swap does NOT include the square profile seals for the mounting studs and EVO seal. What the heck!?

Funny, I don't see anywhere that a person could even buy just the flow valve and EVO bit, but there is a seal kit and a "rebuild kit" that must not have much more than seals, since it's only $12.

I did partway open the pump - just took the big steel cover plate off to see the inner workings. Can't tell how it would come apart the rest of the way, but I do see that the vanes are not all coming out as the pump is turned. That right there could be the issue.

Think I'll make pancakes for breakfast.

Ben

[astro355]

Yes, metal flakes in the p/s fluid equals bad.

Enjoy your pancakes.

[Leeann_93]

Personally, I'd go for the I never want to do THAT again, but that's just me...