Screeching sound from engine

[Panamint]

Greetings,
I have a 2000 Limited 4x4 with 122,000 miles and during deceleration usually at around 40 to 50 miles per hour the engine produces a screeching sound. Now of course, the first thought is a loose belt/s however, we've checked this out both in terms of proper tension & using belt dressing but no luck. I've had the truck since the 17,000 miles and the screeching sound developed at around 70,000 miles and has slowly become worse over time.
Before owning this vehicle, I owned a 1999 SR-5 4x4 and it too developed the same mysterious screech at about the same mileage. My mechanic who specializes in Toyotas doesn't know exactly what it is at this point either so I'm curious if anyone else has run across the same issue and found a solution. The timing belt & water pump have been replaced along with other standard maintenance and that seemed to have no effect on the noise either. Any information or advice would be appreciated. Thank you.

 

[RHeld24]

Does it only make the screech at speed or can you induce it in Neutral/Park with similar RPMs?

Can you notice a surge/loss in lighting (electrical)? Maybe the alternator bearing...

Does it happen with the A/C on? Maybe the a/c compressor bearing/clutch...

 

[Panamint]

The screeching only occurs at speed when there is either zero pressure on the accelerator pedal or more typically when deceleration takes place. The sound occurs with & without the A/C system running although I should double check to see if it is any louder with the A/C on. There is no effect on any of the vehicles lighting. I was thinking it might be a set of bearings somewhere...

 

[RHeld24]

For the sake of diagnosing the problem and not invoking an engine warm-up argument on this thread...

Does it make a difference if the drivetrain is warmed up or if it's cold?

 

[theizzardking]

and not invoking an engine warm-up argument on this thread...

lol, was that thread that bad, hahaha


to me sounds like a wheel bearing as opposed to any sort of engine sounds,and at those speeds it's kind of hard to get out and see where the sound is really coming from, but in my past experiences at those speeds and only at decel, it was pretty much always a wheel bearing of some sort.

unfortunately there's no real way of pin pointing if it's the wheel bearings or not
esp. since it only happens in a certain speed range it means you must move the bearign at those some rpm's to produce the sound.

also i don't think it's coming from your engine as it would be rpm related meaning if your at a stop sign giving it gas to 3K rpms should produce the same sound as if your traveling 40-50 mph's, does that make sense.

i mean correct me if i'm wrong, it just sounds as if you're going about this the wrong way, but then again this is the internet and i have no way of knowing the type of sound the real conditions of it and where it's coming from.

 

[Panamint]

I would say that perhaps when the noise began to develop in the 70,000 mile range that it was more typical while the vehicle was warming up but certainly now it occurs at any time. I've not been able to induce it while parked and playing with the RPMs either. The noise although similar to that of a loose power steering belt is not as loud and if the windows are rolled down then it can be heard much more easily. To me it sounds as if it is indeed coming from the engine compartment.

 

[Beckman02]

I was loging on to ask about the exact same problem. I've got a 2002 SR5 4x4 with 150k that has just started doing the same thing. In my case, it started happening with the onset of cold weather and only makes the sound before things get fully warmed up. After driving a while, the noise goes away. At first, I was so convinced it was a belt (based on the sound), I replaced them. No change so it was not a belt. Will not make the sound while in park so its been hard to locate exact source of the sound.

All fluids including tranny are clean and full. Anyone else have this issue and find a fix for it. I love my SR5 and I hate strange noises.....

 

[theizzardking]

you should find a small non busy road with a big hill and drop it into 1st or 2nd and use the engine breaking to slow you down on your way down the hill, if that doesn't produce the sound i have a hard time believing that it's coming from the engine.

since you can't recreate it without moving in any rpm range it means it either only happens when the engine is under load or it's not coming from the engine bay.

as putting it in a lower gear while coasting down a steep hill should put the engine in the same state as decel from a higher speed, or putting load on the engine through out the rpm range while moving slowly.

this should give you less wind noise to help pin point it as well, I've just replaced 10-15 wheel bearings before in my life and the symptoms sound very familiar , i can't actually hear the noise but the conditions under which it happens just sound like that to me.

at least doing this little test you'll know that it's coming from the engine for sure, because it makes no sense to me why it only happens at certain speeds as opposed to rpm ranges and/or loads on the engine.

i could be wrong or i could be right, lol, doesn't hurt to take the few minutes
to try it.
i'm sorry i can't be of more help guys and really hope you guys get it figured out maybe someone has come across this before and can chime in.
i'm not very schooled in the inner workings of these engines more so in general mechanics. so take my leads with a grain of salt but i really do feel it might be worth checking out.

 

[Beckman02]

That is good advice. Thanks, I will try that and see what happens. I was starting to worry it was something in the tranny making the noise...don't need that. I'll follow up afterwards.

 

[djbrand1]

Mine just started make a "whirring" noise like a noisy bearing as well when the cold came. It only makes the noise on real light throttle and coasting. It is not there when in park or neutral not moving, so I don't think its coming from the engine. It does not make the sound when in 4 wheel drive. Which leads me to believe that its more or less the transfer case. If it is, is there any maintenance to the case that needs to be done besides fluid? I replaced the fluid mobil 1 synthetic stuff about 10k miles ago. Still full and clean. Do I just deal with it until it really breaks or is there something simple that can be done to repair?

 

[theizzardking]

Mine just started make a "whirring" noise like a noisy bearing as well when the cold came. It only makes the noise on real light throttle and coasting. It is not there when in park or neutral not moving, so I don't think its coming from the engine. It does not make the sound when in 4 wheel drive. Which leads me to believe that its more or less the transfer case. If it is, is there any maintenance to the case that needs to be done besides fluid? I replaced the fluid mobil 1 synthetic stuff about 10k miles ago. Still full and clean. Do I just deal with it until it really breaks or is there something simple that can be done to repair?

I could be wrong again but it sounds as if it could still be the wheel bearing , as I think what's going on is that when your in 4wd that wheel is getting power so it's essentially always under load even at deceleration since the rpm of the.engine actively slowing the tire down as opposed to just the friction of the road , maybe the extra resistance is helping keep the bearing quiet .

Honestly I can't see if it was a problem with the t-case why it would quit making nose.when engaged as it's still sending power to the rear , only difference is it engages the front as well, or basically whatever was running in 2wd is also running in 4wd ....

Could also be your guys diffs....

Maybe someone who really knows the depths of the th case could jump in and help.

Just my thoughts on the matter and to be warned post count don't mean a thing , lots of guys on here know more then me , I've just had these same things happen on other trucks and it turned out to be wheel bearings....


As for.work on the the case , nothing you can do except.change the fluid unless you want.to drop it and split it but be 100% that's the case as it's a pita to do that work .

 

[djbrand1]

Yeah, I'm going to get a buddy to ride in the back to see if he can narrow down if its coming from the middle (transfer case) or from the rear (back diff). I know the axle seals were never done on mine as far as I know, but they are still dry.

 

[NDZ]

Same Noise - Sounds like chipmunks under the hood

I have a 98 t4r ltd with 158k and it does the same thing. Gets worse under braking. I tried belt dressing and such then finally found that the Fake Water pump or Radiator Fan bracket bearing has gone out. It progressively got worse and required a bit of monkeying around to replace. Look up that bracket on this site and youll find that its about 120 bucks! good luck