Update- muffler was indeed culprit for loud noise. OMG! I never would have guessed!!


96 4runner, v6 ltd, 4wd, auto, 300k miles
Getting squeel/shrill noise on acceleration. I have removed all the belts, it is still there. The water pump/tb was replace 90k miles ago. No water leaks.
Greased the axles.
Cant get the sound in the garage, in park or even with the brake on in gear.
Maybe it is pinging, or the water pump going?
Other ideas?

Very noticable to me and other cars while driving on the interstate. Can usually just back out of the throttle enough to avoid. Using slow accelerations but that gets difficult pulling the dirtbike.
I looked at a bunch of threads from the search many different ways.

Thanks

 

If your sure it's not the belts all I can think is the power steering Reservoir is empty or very low Causing the pump to squeal.

 

Does it do it sitting still while reving the engine up? If not I would be checking your rear axle.

 

No belts are on and it makes thenoise. So not sure how thep/s pump could be the issue.
Does not make the noise while still and reving the engine, even in gear and reving the engine while still.
I may just replace the water pump and timing belt.
The noise is all up front and seems to be with engine speed but has to happen under significant load.
Valve train? cam bearing? I dont know.

Thanks!

 

Should I be breaking into the engine for this?
Does it make sense to put a new water pump and spark plugs, seafoam in it?

Thanks
Mike

 

I would say no. If it only does it on acceleration I would be looking at a drivetrain issue. Maybe a intake leak. Can you tell an specific area it's coming from?

 

......

 

I would try carefully putting the rear end on jackstands and put it in gear. Slightly engage the e-brake to replicate load. Have someone else press the gas while you listen for the noise. If its coming from the engine area this should help to pin-point it, otherwise I would start looking at bearings.

 

I would check the exhaust gasket it can make some terrible noises

 

Thanks for the help, all.
Noise sounds like it is coming from the engine. But setting it on some good stnds make sense. I can work the throttle from under the hood, being really, really careful. But I dont think it will make the sounds then. At slower speeds I have to be on it pretty hard to get the call of the shrill!
So like going down the interstate, if I start to accelerate I can get the noise to start. Back slightly out of the throttle (though still accelerating) and the noise goes away. Hmm, sounds more like a pinging situation then anything, but the noise is so shrill not pingy. metal on metal at high speeds, but not grinding.

ML

 

Well still have loud shrill. Have taken all belts off, put on new water, pump timing belt and tb pulleys. Pulled both axles, bearing looked good (popped the seal and added bearing grease), drained the rear differential. Put all back together and still have noise.
It now makes it in park with rapid throttle. Hit the trottle hard, the sound is there, hold the throttle and it goes away. Sound like it is coming from the back of the engine.
1. Valves?
2. I put a new flex plate on a year ago. Could something there be causing this?

I am baffled.
Mike

 

Shrill...as in metal on metal? Or high pitched air movement? It almost sounds like it could be a vacuum leak in a hose, air intake, throttle body gasket, etc.

Have you tried using a mechanics stethescope to narrow down where the sound is coming from?

 

Sounds like a possible vacuum leak. Can you post up a video. Does it sound metal or like air?

 

I cant do a video. It sounds like metal, but just maybe it is air leak. Real shrill like metal on metal. I'll check all lines and get under vehicle whlle daughter works the gas pedal.
Where else to look for some air leak?
Thanks!

 

Top or bottom of the engine? If your not sure if it's a vacuum leak spray some brake clean around the vacuum lines and see if the rpm's change.

 

Does it only do it with the better half in the rig? You know how much power these Toy's have...

 

Too funny Swede! Could be the kids?

Some day

Cheers

 

Update: remember squeel on acceleration, no belts on, new timing belt, water pump and idlers.
Noise was there in Park, higher rpms and accelerating (giving more throttle). Could not find any line leaks.
In a desparate move, I added 1/2 guart of Lucas oil treatment.
Noise has gone away, so far (5 mile drive). I am thinking this is not too good!
Thoughts?

 

Time to cut the oil filter open and check for metal. Sounds like a rod bearing squeal. Mine is loosing a piston so I feel for you.

 

Thanks Mark!
Good luck to you too.

Mike