• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Engine whine synced to revs, power steering pump? [video with sound]

J

jmscdgn

Member
Joined
Sep 28, 2020
Location
Los Angeles
Hi TB’ers

Happy weekend to all.

If anyone has the time to throw in their 2 cents on the following sound coming from our 740t engine bay, it would be much appreciated.


Power steering fluid levels are good, though it does appear to be coming from that area though fining it hard to pinpoint— initially thought it was alternator bearings. Hoping if anyone is intimately familiar with this sound, they could shed some light.

Thank you,
J
 
very linear with engine speed, so basically has to match with something spinning with engine. Would need a spectrum analyzer to say if the noise is 1:1 with engine speed or a ratio thereof.

Could try taking off belts to see if noise stops. Also try having someone dampen various components (press against non-moving portions with hand or object, basically change the natural frequency).

Does the noise sustain if you rev up then key off (i.e. cut combustion)?
 
Khrrck said:
If you push the wheel all the way to full lock and hold it there (putting more load on the pump), does it get any louder?
Click to expand...
Thanks for your reply. It doesn’t appear to get louder when full lock. There is a usual (for me at least) “straining” type whine when holding at very hard lock, the steering wheel then feels to have a little motorised push back - just a degree or two - as though the PS pump is saying “no thanks”, and the straining sound goes.
The hard lock straining whine seems distinct from the one closely tied to the revs.

the_hairy_baboon said:
very linear with engine speed, so basically has to match with something spinning with engine. Would need a spectrum analyzer to say if the noise is 1:1 with engine speed or a ratio thereof.

Could try taking off belts to see if noise stops. Also try having someone dampen various components (press against non-moving portions with hand or object, basically change the natural frequency).

Does the noise sustain if you rev up then key off (i.e. cut combustion)?
Click to expand...
Thanks for the reply too. I just ran an errand and now with engine at operating temp the noise is a little less pronounced—could that be a clue?
I’ll run the key-off test when it’s cooled down. Thanks again.
 
cosbySweater said:
Sounds like your transmission. Take the converter bolts off and try again. However before that I would take the belts off and make sure it's not a accessory. To me it sounds like transmission
Click to expand...
MasterBlaster said:
Mechanic's stethoscope.
Piece of vacuum hose stuck in your ear and pointed at/on various things.
Screwdriver with hard handle to feel vibrations.
Many ways to identify odd whining noises and bad bearings.
Click to expand...
ZVOLV said:
Cheap stethoscope to start with.

Then loosen/remove belts.

It could be a bad timing belt bearing.
Click to expand...
Thanks all. I’ll find some time this week and report back. Cheers
 
Thanks all again for your input.

Finally got round to doing a process of elimination after a month away, and it appears to be the water pump bearing.

This was a Hepu pump, and only about 15k miles old.

 
So the pump turned out to be a false flag.
Did a 10qt flush of the transmission yesterday. Began with draining the pan and refilling, then connected a hose to the radiator fitting and started it up. The whine vanished for approx 30 seconds then returned, but less loud than before.

Up on the ramps the sound comes from the front of the transmission, is this a full rebuild situation? or might the issue be isolated to the pump, and can this be replaced without a full rebuild?

If anybody has recommendations in SoCal for this work to be done it would be most welcome. Transmission shifts beautifully minus the noise.
 
Interesting. I would first drop the pan and look for metal shavings. When I find metal shavings in a trans, I usually replace it instead of rebuild it. I flush the lines and cooler after repair/replacement.

I would also unbolt the torque converter and make sure, one last time, that the noise is in the trans before pulling it.
 
ZVOLV said:
Interesting. I would first drop the pan and look for metal shavings. When I find metal shavings in a trans, I usually replace it instead of rebuild it. I flush the lines and cooler after repair/replacement.

I would also unbolt the torque converter and make sure, one last time, that the noise is in the trans before pulling it.
Click to expand...
How does unbolting it work? I'm imaging the the flex plate going bonkers against the converter making a huge racket, no?
 
jmscdgn said:
So the pump turned out to be a false flag.
Did a 10qt flush of the transmission yesterday. Began with draining the pan and refilling, then connected a hose to the radiator fitting and started it up. The whine vanished for approx 30 seconds then returned, but less loud than before.

Up on the ramps the sound comes from the front of the transmission, is this a full rebuild situation? or might the issue be isolated to the pump, and can this be replaced without a full rebuild?

If anybody has recommendations in SoCal for this work to be done it would be most welcome. Transmission shifts beautifully minus the noise.
Click to expand...
You're saying that water pump wasn't it?? Thing sounded exactly like the first video (sorta)
 
conehead said:
How does unbolting it work? I'm imaging the the flex plate going bonkers against the converter making a huge racket, no?
Click to expand...

Nah, the converter can slide back on the input shaft plenty enough to keep it clear of a rotating flex plate.

I had a truck recently that was making a noise. I unbolted the torque converter and the noise was still present. It really sounded like it was coming from the bellhousing, but it turned out to be internal to the engine.
 
ZVOLV said:
Interesting. I would first drop the pan and look for metal shavings. When I find metal shavings in a trans, I usually replace it instead of rebuild it. I flush the lines and cooler after repair/replacement.

I would also unbolt the torque converter and make sure, one last time, that the noise is in the trans before pulling it.
Click to expand...
Thanks ZVOLV. I'm heading to a transmission shop on Tuesday, hopefully they're willing to unbolt the torque convertor to run this test, i think its little out of scope for me in the carport.

I'm not sure which i should hope for more...let's say it wasn't the tranny, what else could be making that whining racket?

conehead said:
You're saying that water pump wasn't it?? Thing sounded exactly like the first video (sorta)
Click to expand...
Yep! the smile as it was wiped from my face would have made for an excellent meme!
 
Last edited:
MasterBlaster said:
Mechanic's stethoscope.
Piece of vacuum hose stuck in your ear and pointed at/on various things.
Screwdriver with hard handle to feel vibrations.
Many ways to identify odd whining noises and bad bearings.
Click to expand...
Try one of these first. You can get a mechanic's stethoscope at HarborFreight for $8, or use a long handled screwdriver with the pointy end held on the suspect part and the other end next to your ear. Get a helper to rev the engine while you listen (or rev it yourself very carefully).
 
jmscdgn said:
Thanks ZVOLV. I'm heading to a transmission shop on Tuesday, hopefully they're willing to unbolt the torque convertor to run this test, i think its little out of scope for me in the carport.

I'm not sure which i should hope for more...let's say it wasn't the tranny, what else could be making that whining racket?


Yep! the smile as it was wiped from my face would have made for an excellent meme!
Click to expand...

That's rough. hate letdowns like that
 
ZVOLV said:
Nah, the converter can slide back on the input shaft plenty enough to keep it clear of a rotating flex plate.

I had a truck recently that was making a noise. I unbolted the torque converter and the noise was still present. It really sounded like it was coming from the bellhousing, but it turned out to be internal to the engine.
Click to expand...
So you have to kinda scoot them away from each other I guess?
 
You must log in or register to reply here.
Back
Top