Doc279

I have this annoying noise when my runner is cold that sounds like a loud buzzing from the drivers side of the engine. It only happens when the engine is cold and in gear below 1500 rpm.

Once the runner engine is warm - the noise is non-existant

I've been under it several times and have taken it to a muffler shop where they raised it up with me in it - It is not the exhaust.
No heat sheilds rattling etc. It is loud enough to be embarrasing in the parking lot at work but goes away within a quarter of a mile. Only there when the engine has been of for several hours or overnight. Any ideas ?

I've checked the air intake system / exhaust / heat shields
stupid cover for the steering shaft knuckle - nothing seems loose or to effect the noise. Don't happen at idle either - just above idle in gear and below 1500 rpm.

tck4x4

Are you positive it is the engine?

Try shifting into 4hi while the noise is happening. I had a similar noise coming from my front wheel bearings. It would go away in 4hi. If this is the problem just repack the wheel bearings and make sure to lube the half shafts where the pass through the spindles.

Juggalo

I posted a thread very similar to this one about my 3VZE being loud when cold, or idiling for a while. From what the guys here told me, it's perfectly normal. I'm pretty sure it has something to do with the fan, so your 4Runner is fine

Donny O.

juggalo makes a good point. the clutch fan will run for a few minutes after starting the truck but jsut sounds like air blowing. another thing that came to mind is maybe a squeaky belt until the belt warms up a bit. put some dish soap on yoru belts when the engine is cold and start it and see if that is it. all I can really think of at the moment....havne't really spent that much time under the hood to knwo what else is on the drivers side.....mabye the ABS controler? I know the one n our bravada will make some noise when it is running its self test shortly after the truck is started.

934rnr

Could be a leaking AIV if one of the hoses pops off it makes a horrrendous noise. It located on the passengers side below the side of the intake the large metal hose that crosses the top of your engine is a air line for it it goes into your air box is any of the hoses there have come off or have a hole in them it will make noise.

Babypig

It definitley isn't the fan. I have the same problem and have yet to figure out what it is.

Doc279

Thanks for all the replies ! The buzzing noise is not a belt, or a pulley. The noise is not the fan. I did find a squeaking power steering pump pulley that was repaired with a fender washer under the pulley nut.
I'm beginning to believe that the noise is in the EGR / Aiv system.
The EGR valve is supposed the stay closed until the engine coolant temperature gets warm - once warm ( normal temp )
the valve will open and close ( flutter ) as needed.

This problem is related to engine temperature and goes away as the engine temperature rises. The sounds resembles an exhaust pipe vibrating against the frame or body - a buzzing vibration. The engine has to be cold / in gear and moving with
your foot on the gas / just slightly below 1500 rpm. That is why it is so hard to find ! You can't strap yourself to the frame and have someone else drive !

Once the engine is warm and the runner has been driven a mile or so the noise goes away - no performance problems / good idle
and other than annoying the Hell out of me - causes no problem.

I've been chasing this stupid thing for close to a year and a half ! :pat:

Mossback74

C'mon now, Macgyver's done it. I'll even drive it for ya.

934rnr

The AIV is open on startup and pulls fresh air in it mixes with the manifold air to reduce hydrocarbon emmissions after it is warm the valve closes and it also opens at cruise which you don't hear when it's open while your are driving because of wind noise and your engine reving. When the engine is back at idle again it closes. Anyway it's about a 99% chance one of the large hoses that lead to it is either come off or has a hole in it.

There is a hard to see large tube for the AIV/EGR that comes off your lower top part of your intake manifold chances are that hose came off it's a real PITA to get back on it right above the PCV. I had mine come off it was doing the exact thing.
It took me about 1/2 hour and alot of cursing to get it back on.
Good luck.

DH6twinotter

Could it be your speed odometer cable? Some of us have had trouble with our cables making a loud buzzing sound when the engine is cold. Sounds like your buzzing is louder than this would be, but thought I'd mention it anyways.

Have fun.
DH6twinotter

dick

Hmm. when you said "buzzing" noise that struck a chord. Years ago I had a very annoying "buzzing" noice from my 90 runner as well. There is some wiring within a plastic conduit that emerges near the valve cover, runs briefly along the firewall and then down along the side of the driver's side fender. I found that when I got some regular foam pipe insulation, split it and put it around the conduit in a few strategic places the "buzzing" went away. Also had a friend at work with the same vehicle experiencing this exact same problem. Could be yours as well!

Doc279

Thanks for the new idea's -
I will check all ! Rained all day here yesterday and was cold.
You guys in the Northeast - lock your hubs.

Thanks for offering to drive the truck - my kids think that I am McGyver already.

I'm quite sure that it is in the AIV system and I will look for the
holy or loose hose - pretty good a CUSSING - I got that part down pat.

Will keep you informed. Just got my manual locking hubs -
I never had any problem with the ADD hubs until sliding in to a ditch trying to pull a jeep off a log. - Backing up will allow the hubs to unlock - and your back to 2 wheel drive !
Why would Toyota use these ?

Have a great day all