[Seiji_1113]

so i just bought a 1998 limited 4runner about a month ago and ive noticed a whining noise during acceleration for the last few weeks.
It happens both when its cold or warm, only when in gear as i accelerate. The pitch of the noise increases with RPM and gets lower again when it shifts and once again goes up with RPM. It does it in all gears except for 4th gear. Once im at cruising speed with little load the sound goes away.

I have an automatic with no supercharger.

Ive just done a transmission pan drop and fluid flush(not a power machine flush), filter clean. The old fluid was a dark red, not quite brown. The magnets had some sludge and some very small metal shavings but nothing bigger than a couple mm.

Ive been reading around and heard it could be the torque converter but would like to start by fixing the little less expensive things. especially because the sound isnt all that loud.

ive also replaced the fuel filter and all drive belts.
i am thinking of changing the diff fluids and transfer case fluids as well.

Any thoughts?

Thanks

[shayes11]

I just had the same thing happen to me. Bought a '99 Highlander that had a whine that directly correlated to RPM's. In my eagerness to get a 4runner, I overlooked it and just assumed it was the brand new belts.

Three shops later and everyone agreed that my transmission pump was on its way out. I had three options, reman from Toyota, low mileage used swap, or replace the pump and hope it holds up. I ended up going with a low mileage swap, so far so good!!

I know that's not the answer you were hoping for, but I figured I'd let you know what happened to me. Maybe some of the other, more knowledgeable members can chime in.

[the great him]

its not your tranny pump... im not sure what it is, but they all do this. without hearing the sound specifically it couldnt tell you what it was... -it could just be some radio freq noise/interference coming though your speakers, it could just be the normal whine that these motors make under acceleration. mine does it, no i dont have a SC(yet), its more pronounced in cold weather, especially first thing in the morning when the motor is cold.

[shayes11]

Well I hope I'm wrong, but I had two HIGHLY reputable shops and one EHH shop all agree that it was my transmission pump. Maybe your sound is different, and I'm hoping it is!

[the great him]

of course a shop is gonna tell you you have a part going bad.... hello thats how they make money, by selling work. lots of shops will just throw parts at noises (even reputable shops and dealers) and swear up and down that yeah this part or that is going out bla bla bla bla... do a search on here about the noise, search engine or motor whining under acceleration. your not the first person to say something about this.

-it could also be a pulley on the motor... did those shops tell you that? did they hook anything up to the trans, like a flow meter? to measure the volume of flow the pump was putting out? i bet not, and if not they i can assure you they can not accurately tell you that the AT pump is on its way out. there are guys on here that run their trannys a lot harder than you probably do and put much harder/heavier loads on them than you(i bet im one of them) and they dont have tranny pumps going out. even guys with the SCs dont have pump failures, they have clutch packs that go bad or valve bodies that go bad, but not the pump. thats not to say that the pump can not go bad or could not fail but its highly unlikely

[BTO]

Could it be the Power Steering Pump? They do whine when they are either low on fluid or getting ready to crap out.

[shayes11]

Look man, I'm not trying to argue with you or anything. I'm just stating a fact. I had a transmission tech at Toyota of Escondido, James from The Truck Shop in Miramar, and the dealer's own mechanic (who works for the dealer, doubt he's going to side with me a week after buying the truck) and ALL of them said tranny pump. The noise was only present when in gear, you could rev it as high as you wanted in neutral and nothing.

The Truck Shop DID run a flow meter before swapping the used transmission and the numbers were dismal. Now I have a used transmission and there is no noise. Again all facts.

I can't attest to how hard the trucks transmission was run before, because I just bought it 3 weeks ago. By the looks of it and the feel, I was honestly surprised.

I seriously hope that this isn't the case with the OP's noise.

[BrazilianT4R]

Originally Posted by BTO

Could it be the Power Steering Pump? They do whine when they are either low on fluid or getting ready to crap out.

Totally agree!

[vincer77]

My first thought was alternator bearing. Easy to rule out, just put a long screwdriver against the alternator and put your ear against the handle. If you hear the noise clearly, then that's it. I test drove a 4runner with that whine and I thought it was coming from the trans.

[Seiji_1113]

Hey all, thanks for the replies.
If it was the power steering pump or the alternator., would it not be making the noise regardless of if it's in gear or not? If I rev in park it sounds normal.. The sound is only present when the engine is under load and accelerating..
I'm really hoping that it will be a cheap fix.
I just did a Tranny flush and when I did it I watched the pump, pump fluid out of it and it seemed to be pushing the fluid through fine. I know a visual check probabaly doesn't mean much but maybe it does.
Any more ideas? I will check the power steering fluid tomorrow

[DGO-SR5]

I had a similar noise with my 98 Limited, but do not experience it with my current 96. Mine would not make the noise unless it was in gear, this includes reverse. The moment I shifted from park into reverse or drive I could here a whining/groaning noise which would increase with RPM as I drove. I do repeat that this noise would completely go away if it was in park or neutral. My transmission fluid came out very dark when I changed it the first time after purchase and although it felt fairly good I will say that my 96 trans is much smoother and more responsive. I personally think it is a trans pump or that the torque converter is slightly worn. I never felt anything weird that went along with this noise but it was just annoying and I do think its something in the trans itself. Double check that the noise is only present when placed into gear even with your foot on the brake and we can narrow it down.

[Seiji_1113]

Yes the noise is there when I'm in gear with the brake on but it's very quite. Becomes more noticeable when I accelerate a bit.

[jaybee]

its sounds like a tranny issue..i would change the tranny fluid....

[Seiji_1113]

I just did last week. No changes.

[DGO-SR5]

Changing fluid did nothing for me either although adding some Lucas stop slip seemed to make the noise a little softer, but still there for sure. I really think this issue is transmission related and the torque converter most likely. If it doesn't seem to slip or act funny I wouldn't worry about it though and just put up with the noise for now.