Squealing on hard acceleration

Over the past few months I've noticed my Outback makes a squealing noise when I accelerate hard. Initially I believed this to be loose / worn belts so I replaced them a month or so ago. The problem still persists so I am thinking it is the bearings on either the air conditioning compressor (unlikely as it happens when the air conditioning is off), alternator, or power steering pump. Water pump, timing belt, and all rollers / tensioner was recently replaced so those items are known good.

 

What is the best way to narrow down the specific part? The air condition is run off its own belt so it would be easy to identify it merely by removing the belt. The alternator and power steering is a little more difficult because they're both driven by the same belt. Perhaps I should start with the alternator and, if that doesn't solve the problem, then the power steering pump? Any way to test the alternator as it only occurs under high revolutions? Maybe I can take it to the auto parts store for testing. Any advice on discount places to buy an alternator?

Update: I ended up replacing the alternator with a new one and the problem remains. The noise occurs when engine speed reaches approximately 3200 RPM and continues until about 4200RPM. It only does so under load (i.e. the vehicle is under acceleration). It does not make the noise when parked and the accelerator quickly pressed. Nor does it appear to do so when cruising with the engine within the aforementioned RPM range.

 

I ended up reinstalling the original alternator and tightening the belts a little bit more just to be safe (problem still persists). My next thought is the power steering pump.

I'm interested too, my 98 legacy squeals as soon as I hit 3800 RPM. bump!

yup, this is happening to me as well with my 97 OB, but I haven't tried fixing it yet. I thought it was the timing belt + rollers, but i guess not...bump!

remove the alt belt and drive around the block.

does it make the noise.

My 98 lgt is doing this also, but I know why. My throw out bearing wasn't changed with the last clutch change. The person I bought the car from just changed out the friction disc and nothing else. The bearing sqeaks and rattles at idle, then at high rpm makes all kinds of racket. It does make more noise when under acceleration.

Jeff

Are you sure its not the exhaust system. These cars are notorious for having pin holes over time that squeel like crazy under heavy acceleration... Just like some mitsubishi eclipses. I know my stock leggy exhaust was squeeling

Thanks for the accessory belt suggestion I'll try it soon, but I did some googling this morning and somewhere someone said slipping clutch disks can squeal in our automatics. I'll look in my history and post a link later this evening, but it does make sense; squealing at a certain rpm range and all. I'll drive my car soon to see if my acceleration rate changes once the squealing starts.

remove the alt belt and drive around the block.

does it make the noise.

 

I'll give that a try...possibly this afternoon but definitely over the weekend. I get the feeling it's not going to go away.

Thanks for the accessory belt suggestion I'll try it soon, but I did some googling this morning and somewhere someone said slipping clutch disks can squeal in our automatics. I'll look in my history and post a link later this evening, but it does make sense; squealing at a certain rpm range and all. I'll drive my car soon to see if my acceleration rate changes once the squealing starts.

 

Interesting. I should note I do not see a change in the acceleration rate when the squealing starts (or ends). Is that a symptom of the clutch disks slipping?

I wan't to say bearing but unsure.. I like the idea of driving without the accessory belt.

 

If you do that and its still making noise then the only bearings could be timing belt/Wpump related.

checking those may be a headache but you could take the timing cover off and put a go pro or just tape a camera in there (Facing the timing belt. Not actually in there )

 

record and repeat your test and let the video tell. repeat another test with the camera closer to the transmission if you need another point of view, or listening.

I wan't to say bearing but unsure.. I like the idea of driving without the accessory belt.

 

If you do that and its still making noise then the only bearings could be timing belt/Wpump related.

checking those may be a headache but you could take the timing cover off and put a go pro or just tape a camera in there (Facing the timing belt. Not actually in there )

 

record and repeat your test and let the video tell. repeat another test with the camera closer to the transmission if you need another point of view, or listening.

I replaced the entire timing belt system (belt, idlers, tensioner, and water pump) a few months ago. So unless one of the replacement parts was bad it shouldn't be anything related to timing.

 

If I pull the alternator / power steering belt and it still makes the noise I'll probably take it to my mechanic to have him check the timing work to verify nothing is wrong there.

My dads 97 outback did that same exact thing. It never seemed to get better or worse. But it would only do it under considerable acceleration. He even replaced the intake and other vacuum parts. Either way it was like that for years. It was really just a slight annoyance.

My dads 97 outback did that same exact thing. It never seemed to get better or worse. But it would only do it under considerable acceleration. He even replaced the intake and other vacuum parts. Either way it was like that for years. It was really just a slight annoyance.

It's been interesting to hear others have the same problem and even more interesting to hear some haven't identified the problem. If removing the alternator / power steering belt doesn't solve the problem I'll talk to my mechanic to see about having him check the timing components again. If he informs me it's more than a casual inspection I'll probably just let it go. I just wanted to ensure it wasn't the bearings on anything as I don't want them to seize while and leave me stranded.

mine does the same thing, cant tell you what it is but I can tell you just about everything that it ISN'T. it is NOT the timing belt, or bearings, tensioners, a/c, alternator, "baffle in muffler", accessory belts, throw out bearing, "as my car is an automatic", vacuum hoses/tubes, clutch disks inside transmission, wheel bearings, axel shafts, u-joints, or drive shaft bearings. cause I've replaced ALL that, still whistles like a mo fo under hard acceleration. only think I haven't done is anything with the intake so it could be something with the factory intake, maybe dirt buildup or something.

are you all sure ths is a squeal ,

not a rattle.

the exhaust shieds will rattle,

sometimes at just a certain rpm range.

 

check for loose shields on the y-pipe,

the cats,

and maybe the long one in between the drive shaft and the exhaust.

 

the easiest solution is stainless hose clamps for the y-pipe and maybe the cats.

Update: I removed the alternator / power steering pump belt and the squeal persists. I am not surprised at these results.

 

I am now considering it may be something within the transmission. The squeal begins when the transmission kicks down (recall this only happens under hard acceleration). Perhaps it's related to the rough 1 -> 2 shift. I'm going to check the transmission fluid level. I may even have it replaced (again, had it replaced last year when I first got the car). If that doesn't solve it I think I'm just going to accept it is what it is. The vehicle is operating fine. Aside from being noisy under hard acceleration (something I don't do a whole lot) it's operating fine.

 

John, yes...I am confident it is a squeal.

is it a squeal or a whistle? does it sound like its boosting? mine sounds like a turbo at full spool. even though its n/a, I like the sound, just want to know what's making it.

are you all sure ths is a squeal ,

not a rattle.

the exhaust shieds will rattle,

sometimes at just a certain rpm range.

 

check for loose shields on the y-pipe,

the cats,

and maybe the long one in between the drive shaft and the exhaust.

 

the easiest solution is stainless hose clamps for the y-pipe and maybe the cats.

 

 

 

my exhaust shields rattle but its a VERY different sound.

is it a squeal or a whistle? does it sound like its boosting? mine sounds like a turbo at full spool. even though its n/a, I like the sound, just want to know what's making it.

It's a squeal. It sounds exactly like a belt slipping or a bearing failure. Since I've replaced the belts, removed them (alternator / power steering, air conditioning), and had the entire timing system replaced (including the water pump) it's very unlikely any of the driven components is at fault.

Yesterday afternoon I checked the transmission fluid level and it looked as it if was low. This was a hot check which is the preferred method of checking the fluid. This morning I performed the cold check and received the opposite results. According to this test the transmission has too much fluid (it reads above the hot full line marker). I haven't added any since the shop performed the work last summer. And things looked OK at that time.

 

I am puzzled how the two different checks would yield completely opposite results. I cannot be certain the vehicle is 100% level. The parking space looks level but eye balling it can be deceiving. I have decided to turn the vehicle around and see if the cold check yields different results. If the vehicle is not level theoretically turning it around should give me the opposite results. I'm going to let it sit to give it a chance to settle (and cool down for the brief amount of run time to turn it around).

 

Has anyone else experienced mixed results when checking the transmission fluid. I've been checking the oil level in my vehicles for many , many years. It's one of the most easiest checks on can perform. The test for the transmission fluid seems right on par with checking the oil level. Which is why I'm puzzled. Any guidance or thoughts?

im not sure about subarus specifically but some vehicles have to be checked running in the neutral position., that lets the "correct" amount of fluid return to the pan.

im not sure about subarus specifically but some vehicles have to be checked running in the neutral position., that lets the "correct" amount of fluid return to the pan.

You may have just solved my disparity between the cold and hot readings! The cold readings were taken without the engine running. The hot readings were. I assumed, as the owners manual doesn't go into detail about the cold reading to the extent it does the hot reading, the engine needed to be off for the cold reading. But now I realize that doesn't necessarily need to be the case. I'm going to perform another cold reading with the engine operating. Unfortunately I now need to wait for it to cool down so I can't do it now.

lol, yea and every manufacturer is different.

Update: I performed the cold engine test with the engine running and I now read the fluid level is low. This is consistent with the hot reading. Upon reflection I can't believe I didn't think of this earlier. It explains something which has puzzled me for almost a year. Tomorrow I'll add some fluid and see if there is any change. This might help with my hard 1 -> 2 shift too!