"roaring" noise coming from the front

[t4r2k7]

hello all.
I have a stock 2007 SR5 v8 4 runner

recently I notice and intermittent "roaring" noise under acceleration.

I can't be 100% sure, but i feel like it happens when it's really hot out and when the A/C is on.
but it's very intermittent.

for instance. leaving work it was 90+ out and i had the a/c on. it "roared" all the way home, but it's really "under acceleration" if i let off, i don't hear it.

however the next morning, drove to work with the a/c on and nothing - everything sounded normal.

the a/c works fine. could this be something in the compressor going bad? bearing or something.
or is it a front diff issue?

103k miles, no issues anywhere else.
I've had it happen briefly and intermittent before, but recently it feels like it's getting worse / more common.

Thanks!

 

[fdbyrne]

Have you changed your differential fluid recently? What did the fluid look like? Was there an abnormal amount of metal on the magnet?

 

[t4r2k7]

Have you changed your differential fluid recently? What did the fluid look like? Was there an abnormal amount of metal on the magnet?

I have not changed them yet.
it just turned over 100k recently.
I understand the tranny is not serviceable?
I do change the oil and air filter regularly and have changed the plugs once.
everything else has been doing fine.

do you think it could be a front diff fluid issue?
i need to do some testing and when it's doing it, turn the a/c off and stop/start my drive up and see if it still does it.

I just figured i'd ask here in case someone knew right away what it was.

 

[TechWrench]

What you may be hearing is the engine cooling fan. The fan is operated by a fluid clutch, that is regulated by temperature. As the temp increases, the clutch 'stiffens' and turns the fan faster, as the temp decreases, the clutch 'loosens' and the fan slows down. Under normal circumstances, the fan always turns slower than the belt pulley that drives the clutch. If the fan clutch starts to fail, it can lock up and make the fan turn at full speed, which will cause a roaring sound, especially under acceleration, because the fan is not designed to normally turn that fast. One way to check the fan clutch is when the engine is cold, you should be able to grab a fan blade and turn it with out much resistance. If it doesn't move or with a lot of resistance, then the fan clutch may be failing. If so, it is a fairly easy part to replace. If you are not comfortable doing this yourself, take the vehicle to a reputable shop or dealer to have it checked out.

 

[t4r2k7]

What you may be hearing is the engine cooling fan. The fan is operated by a fluid clutch, that is regulated by temperature. As the temp increases, the clutch 'stiffens' and turns the fan faster, as the temp decreases, the clutch 'loosens' and the fan slows down. Under normal circumstances, the fan always turns slower than the belt pulley that drives the clutch. If the fan clutch starts to fail, it can lock up and make the fan turn at full speed, which will cause a roaring sound, especially under acceleration, because the fan is not designed to normally turn that fast. One way to check the fan clutch is when the engine is cold, you should be able to grab a fan blade and turn it with out much resistance. If it doesn't move or with a lot of resistance, then the fan clutch may be failing. If so, it is a fairly easy part to replace. If you are not comfortable doing this yourself, take the vehicle to a reputable shop or dealer to have it checked out.

Awesome.. so glad i posted.
Thanks for the tip!! I will check it this evening.

 

[fullboogie]

What you may be hearing is the engine cooling fan. The fan is operated by a fluid clutch, that is regulated by temperature. As the temp increases, the clutch 'stiffens' and turns the fan faster, as the temp decreases, the clutch 'loosens' and the fan slows down. Under normal circumstances, the fan always turns slower than the belt pulley that drives the clutch. If the fan clutch starts to fail, it can lock up and make the fan turn at full speed, which will cause a roaring sound, especially under acceleration, because the fan is not designed to normally turn that fast. One way to check the fan clutch is when the engine is cold, you should be able to grab a fan blade and turn it with out much resistance. If it doesn't move or with a lot of resistance, then the fan clutch may be failing. If so, it is a fairly easy part to replace. If you are not comfortable doing this yourself, take the vehicle to a reputable shop or dealer to have it checked out.

This. Had the same problem with my old Durango and the sound you describe is the same. I'd bet money it's the fan clutch. Rock Auto has very good prices on fan clutches.

 

[ARunner]

I agree it's your fan. But don't assume it's bad. That would be premature failure IMO. However, if it does seem like it's running a lot, check your coolant and keep an eye on your temp gauge. If it's running a lot I would suspect your radiator may not be operating at peak efficiency. The fan is running because the engine is reaching such high temperatures. It's a good thing you hear that roar because it means the engine is cooling off. That is unless it's broken. The description you give makes me think it is working correctly. Mine generally will roar only after sitting in traffic for extended periods on hot days with the AC cranked.

 

[t4r2k7]

It's funny that it's been just about a year since i first posted this request.

I kind of dealt with the issue last summer as it was a (oddly) fairly mild summer where i live. the noise only happened when it was really hot out.

we've hit the 90's a few times this year here and I noticed right away it started again.

So i decided i would take it in and have it replaces. I'm sure i could have done it myself, but it's hot here and didn't really feel like messing with it. and i figured how much could it really cost after all.

Took it to the dealership and said i want my fan clutch replaced and the serpentine belt while you're in there.. it's still stock (2k7 119k miles)
figured it was due.
I asked about the water pump but at $1200 i said yeah no.

They called the next day and said "the tech said it's working fine, the clutch engages and disengages as it's supposed to"
I told them, it only happens when it's over 90 degrees out. (it was low 80's when they tested)
I said just go ahead and replace it anyways. summer is here and it's starting to get in the 90's and has happened several times already.

I get the 4runner back ($514 later) and everything seems fine.
Yesterday it was 93 here. I take my family to the store everything is fine.
hit the highway no problems.. get off the exit hit a stop light, where i'm sitting for a minute. and when i take off.. bam.. ROARING again. i'm like WTF. and it did that all time while were out shopping.
after dinner at a restaurant it's now down in the mid 80's. and guess what.. no more roaring.

I can feel when the clutch doesn't disengage, it's like a bit of an extra weight is on the vehicle and it roars. but again, only when it's over 90 out.
anything cooler than that, and it's fine.
it never did it once during the fall, winter or spring.

soo thanks for reading all that back story.

thoughts on what i should do? if they did indeed replace it, why is a brand new one doing the exact same thing?
Thanks!

 

[blackoutt]

They called the next day and said "the tech said it's working fine, the clutch engages and disengages as it's supposed to"

Because it's not broken. When your AC is on and your engine is hot your fan comes on. They are loud.

 

[t4r2k7]

Because it's not broken. When your AC is on and your engine is hot your fan comes on. They are loud.

appreciate the reply. but I bought it new in 2007.
it only started doing that last summer.
other posters indicated it was due to faulty clutch fan..
how come? if it's not a legit issue.
loud, it sounds like a semi truck taking off, i can't imagine that is supposed to sound like that.
i did try running without A/C and it still did it.

 

[blackoutt]

appreciate the reply. but I bought it new in 2007.
it only started doing that last summer.
other posters indicated it was due to faulty clutch fan..
how come? if it's not a legit issue.
loud, it sounds like a semi truck taking off, i can't imagine that is supposed to sound like that.
i did try running without A/C and it still did it.

Semi's in traffic taking off usually are running the fans 100% lol. Sorry I'll try to be more helpful here...

Some other things to check,

1. If you're doubting the clutch was replaced, make sure they show you the old part and also look at the new one should look...new.

2. It seems to me your fan is running a lot. They will usually run when AC compressor kicks on, but mine doesn't run at full engagement much at all without AC on, even in 90+ weather. Check coolant level, check coolant temp sensor. Usually just a resistance measurement at known temp. Edit: not electrical fan as mentioned below, clutch type only so coolant temperature sensor has no input on fan. I was thinking of the troubleshooting on my KTM fans.

3. When was the last time your coolant was flushed? You should have done timing belt by now, which is a great time to do the water pump and flush the coolant. Only ever top off using the correct Toyota coolant. Ethylene glycol and propylene glycol don't mix.

4. Potentially dirty/damaged fan blades or obstructed fan shroud causing a more unbalanced sound than you're used to.

 

[BlackWorksInc]

When on the freeway, the natural cooling effect will cool the fan clutch and let it mostly freewheel. When you slow down, the fan clutch will soak up heat and engage. You'll here it roar because it takes a bit for it to cool down and freewheel again. It sounds like it's working fine, particularly if this is happening only in 90 degree weather after popping off the freeway for a bit.

It's not off/on like an electrical fan, can't say as to why you just now noticed the noise. But it sounds about normal for a fan clutch in hot weather.

 

[t4r2k7]

alright guys.. appreciate all the info!
I guess i won't worry about if it's normal.
i don't profess to have the best memory, but i swear i can't remember noticing this issue for the past 5 years.. only last year did i feel like, hey this doesn't sound or feel normal.

I will check coolant levels this weekend.

 

[ToyotaNewby]

I figured I would try and comment on this post since it has been several years, I have a 2007 Toyota 4runner V8 as well with the same issue. I had the fan belt clutch checked out and it was working properly. I also had a new radiator, transmission cooler, all new hoses, and new thermostat installed about 3-4 weeks ago but it is still doing it. Timing belt and water pump was replaced at about 125k but it still did the roaring at that time too. I wanted to see if you still have your vehicle or if the issue ever turned into anything. I am not a car guru like a lot of people on here but I have a hard time believing this is "normal". Only thing I can think of is the engine is going on it, I have about 180k miles and I have seen these cars with a lot more than that. Any insight would be helpful. Thanks!

 

[t4r2k7]

I figured I would try and comment on this post since it has been several years, I have a 2007 Toyota 4runner V8 as well with the same issue. I had the fan belt clutch checked out and it was working properly. I also had a new radiator, transmission cooler, all new hoses, and new thermostat installed about 3-4 weeks ago but it is still doing it. Timing belt and water pump was replaced at about 125k but it still did the roaring at that time too. I wanted to see if you still have your vehicle or if the issue ever turned into anything. I am not a car guru like a lot of people on here but I have a hard time believing this is "normal". Only thing I can think of is the engine is going on it, I have about 180k miles and I have seen these cars with a lot more than that. Any insight would be helpful. Thanks!

I do still have it. I have about 160k on it now.
was getting a bad shudder during acceleration. had the stock suspension still and the ride was horrible so i figured time to take it in. turns out the shudder was from a bent front axle, i also noticed a clunking sound from time to time when putting it in gear from park. that is gone now too. i got new shocks and struts but the ride still kinds of sucks, so i'm not sure what to do about that yet. as far as the roar, i had the fan clutch replaced even though they said it was fine, it still roars from time to time, but only seems to do it when it's really hot out. I've just learned to live with it, as it doesn't do it most of the time. I've been debating on getting a new ride or not. hard to justify a car payment, when i'll probably get 200k out of this. i looked at new ones, but all the 4 runners are v6 now. so i'm not sure what i'll do. anyways. good luck with yours.