I have a 99 Tacoma Prerunner w / big 4-cyl, 144k miles, automatic, AC, power steering. runs great, I take care of it, hardly ever any problems.

Recently, when I very first start it up and it's idling, I hear a rythmic repeating squeak from the engine compartment. Sounds like it's coming from the vicinity of the power steering pump / fan clutch / water pump but it's hard to tell exactly.

After about 15-20 seconds the engine increases revs 50-100 rpm as some sort of warm up cycle or something (it actually sounds like a fan kicking in but the fan is pulley not electric so it's already spinning) and the squeak goes away never to be heard again. Doesn't come back while I'm driving or sitting or idling or braking or anything. But if I shut it down and start it back up I can repeat this squeak cycle every time.

The squeak is getting more noticable over time and I'm thinking something's gonna break eventually, so I'm checking here first before taking it to some shop.

Thought it could be the power steering or AC but turning the wheel and switching the AC doesn't change things. Well, switching the AC makes it go away, but only if it's switched and the revs increase as a result, so it's not the AC clutch, it's the increase in revs that stops the squeak. Turning AC on/off after the squeak goes away doesn't do anything, I can't make the squeak come back once it's gone.

I thought maybe it was the fan clutch, still not sure about that. Maybe it's possible that it's squeaking at low revs but a bit higher and they go away? Maybe the squeak never comes back after startup because it never drops to those very low first starup revs again? It *never* squeaks at any other time than this initial startup low rev period.

Any suggestions?

 

When's the last time you replaced the belts?

 

X2 on the belts. Even if they are newer they may just be loose. If they are old, replace them. If newer, check their tension (with the engine off)

 

I had to retighten mine after replacing. easy and quick fix.

 

NICE!! Because he's a noob? Or is it the Florida? Or maybe you're a lawyer? ....the kind that writes warning labels? (Sorry, just kidding around)

 

Take the belts off, check each accessory pulley by turning them by hand and feeling for roughness, replace as needed, either re-install your good belts or replace them and set to the correct tension.

 

Thanks for the tips, I do need new belts. But if it was the belts wouldn't they chirp at different speeds, under different loads, revving it up, etc? Why only at initial startup and then go away 50-100 rpm higher?

 

It's comon for a belt to squeak a little when it's cold & then stop as soon as it warms up. It is also possible the you have a bearing in one of your pulley's going bad which is why I recomend that you remove the belts & check them all.

 

what your probably hearing is the belt slipping at the crank pulley. it's because the belt is stationary at that point and when you turn the truck over the crank pulley goes from 0 - operating rpm rapidly, until the belt catches up to engine rpm it will squeal.

also as a note like yotarob2005 had mentioned if a pulley itself whether it be the tensioner pulley, ac pulley, alt pulley or whatever, if they are starting to go (especially the tensioner pulley) and they are cold sometimes they will also chirp until they heat up.

Without actually having a video of this we cannot tell what you have is a chirp from a pulley or a squeal from a belt.

Do yourself a favor though, if you get new belts, spend the little extra coin and get some gaterbacks. Every other brand I have tried has always loosened up where I had to keep tightening them over and over again till they stretched too far and could not pull my alternator enough to tighten them correctly.

 

It's not a case of cold belts, I can drive it all day, turn it off, start it up, and it squeaks until the engine does that startup thing (I don't know what that even is, it just revs up 50-100 rpm about 10-20 seconds after startup each time)

 

It squeaks for 10-20 seconds, not a second or two. The belts and pulleys are definitely caught up, it's not squeaking from slippage.

Again, it squeaks at startup whether it's warm or cold, it's not a case of the squeak going away when it warms up. It's related to extremely low initial startup rpm.

I can take on on my phone if that would help. Is there a place here to post it?

Thanks for the tip!

 

putting a video on youtube and posting the link here is your best option.

if it's squealing for 10-20 seconds and not for like a second or two then it's probably because the alternator is at a load charging the cold battery and the belt is slipping there. Which also explains why the engine rpm changes after a few seconds. The rpm change could also be because of drag from the fan clutch till it warms up and releases the fan but less likely the cause of the squeal. You have a few things going on at the same time on start up that creates the rpm drag on the motor which is normal. The squeal is perfectly normal if your belts are either loose or old.

 

My tacoma 2.7 4 cyl had the same issue, with a chirping sound at startup before the engine idle revs up. my belts all looked ok, i tried to tighten them anyways to see if it would help. About a week later i'm driving home from a friends house and it starts chirping really loud while i'm driving which it hadn't done ever before. i got it home a few miles away and took it to a mechanic the next morning. turns out it was the big center pulley (don't know the name) but its the only one that has 2 belts coming off of it directly in the middle of the engine. pretty cheap fix with all new belts and new pulley couple hundred bucks. everyone thought it was my water pump, but it wasn't, so be careful and check everything thoroughly if your going to do it yourself

 

Ok, here you go... http://www.youtube.com/watch?v=GJezRTqHNlU

Note how it starts up... you hear the rhythmic chirping after just a second... at 17 seconds the engine revs up on it's own (as though I stepped on the gas, but I didn't, actually sounds like a fan kicking in, but the fan spins right from startup, it's just the engine revving up)... and at that point the chirping ends never to return... until I shut it off and start it again, and it will do all this over again regardless of how long you run it or how hot or cold it is.


I guess it could be the alt load, but I don't think that's related to the rpm increase... I also think the rpm changing is some normal startup thing, maybe controlled by the ECM or some vacuum condition at startup.... I don't think it's the fan clutch either, because it does it each time it starts, whether everything is hot or cold.

 

that's not a chirp and it's not a squeal its more of a tap, when you hear the fan switch on is when it goes away.

those 2.7's have a fan clutch right? almost sounds like the fan itself is hitting off the shroud.

 

Maybe the sound in the video isn't so great, but it's definitely not a tap. Nothing is hitting anything, it's a really short squeak. It's either a belt slipping, a bearing squeaking, something like that. If you think about it... if it were a tap it would have to be tapping much faster than that since the engine is doing around 1000 rpm. This sound is only like 2 squeaks per second. The fan hitting the shroud would sound like a buzzing noise because it would be hitting alot more than 2/sec at the speed it's turning.

And the fan isn't electric, it's belt driven, so it doesn't "switch on". The fan does have a clutch that contains fluid but there's nothing electric about it.

Right now I'm thinking it's a pulley, possibly one of the larger ones because of how many squeaks pers sec it's happening... not sure yet. Right now I'm leaning towards Toyoda22 and his big center pulley theory.

Thanks for all your tips so far, much appreciated!

 

I agree with xxxtreme22r that the noise stops when the fan turns on which would lead me to believe it's coming from the fan clutch. I would go around with a stethescope and try to isolate where the noise is coming from.
Right now I'm unsure if the idle surge and the noise are related or separate issues.

 

The fan doesn't "turn on"... the fan is not electrical, it's belt driven.

 

you can obviously not hear that fan spinning until that noise goes away which is what we are saying. My best guess right now is either the fan clutch is bad somehow. or the belts are slipping on the fan pulley preventing the fan from spinning at full rpm when you first start it. Which you will when the fan clutch is cold. When I first start mine the fan clutch is locked until it warms up slightly then the clutch disengages then you hear the fan stop spinning fast (yes it still spins) then when the clutch heats back up to where it will engage again then you hear the fan once again. When I first start mine and the fan clutch is cold the fan will draw on the motor till the clutch releases then you can hear the motor gain 100 or so more rpm because of less drag. I know mine is a 22r but the theories are the same.

 

I think they mean when the fan clutch locks up, the fan "turns on".