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Discussion Starter · #1 ·
hello guys n gals.
My 2002 AWD Astro Cargo makes a very loud whining noise similar to a air raid siren, only when I press the gas(accelerate) but NOT when I am coasting( foot off gas).
I cant tell where it is coming from, any ideas?????? I'm guessing rear end. No noticeable leaks anywhere. Is this safe to drive????
 

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Sounds like an exhaust leak to me.
 

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"???" Maybe if you hold the phone a little closer to the truck...

Do some things like put the truck up on jackstands, and have a buddy work the pedal, while you sniff around under the truck to see if you can pinpoint the location where the noise is coming from. Don't forget that noises are subject to "telegraphing" in other words being transmitted from the real location to where you may think it is coming from. Getting closer to the problem will really help you out.

Good hunting and let us know how you are making out.

Bob
 

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CHEVYKEVYSS said:
hello guys n gals.
My 2002 AWD Astro Cargo makes a very loud whining noise similar to a air raid siren, only when I press the gas(accelerate) but NOT when I am coasting( foot off gas).
I cant tell where it is coming from, any ideas?????? I'm guessing rear end. No noticeable leaks anywhere. Is this safe to drive????
I have that in my van when I floor it,And strangely the the whining is not there when my wife not in the van.Coincidence I think not.
 

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There could be bunches of causes but if it is only there under load you should look first at any of the mechanics that will get torqued. Most people ignore the different body panels but when you accelerate the body panels twist and shift as well and it could be something like a bit of metal rubbing on a moving part ( something rubbing on the driveshaft or maybe rubbing against a wheel when under acceleration} Thats a hard noise to pinpoint but as recommended in an earlier post. Get it up on jacks and listen from under the van.
If there is no noise that way then it is a body torque problem so look for metal rubbing.

A J
 

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Discussion Starter · #6 ·
Well this noise is not any body panels rubbing, that much I'm sure of. As far as a muffler, I have to say that I have never heard a noise like that come from a muffler. To me it sounds like the rear end.I would jack it up but I dont have a level surface anywhere on my property, guess I'll have to throw the jack and stands in back and head down to the park :lol: Can I post video on this site? If so I will take a video as I'm going down the road and you can at least hear what I'm talking about. It is a whining sound that starts out low and increases in pitch the faster I go.By the time I'm at highway speeds it sounds like a piercing high air raid siren.
 

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Try shifting to neutral and let off the gas when the noise is peaking, so as to see if the noise follows the engine speed, or the truck speed. You can sort of eliminate a lot of possibilities if you go about it logically.

Also, if you lift one rear wheel off the ground, start the engine and whiz the tire while you have a stethoscope on the differential (use a really long piece of metal rod) you might be able to better tell what is going on.

Got the idea ? It could be as simple as a bad bearing, but you gotta isolate the problem first.

Bob
 

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CHEVYKEVYSS said:
hello guys n gals.
My 2002 AWD Astro Cargo makes a very loud whining noise similar to a air raid siren, only when I press the gas(accelerate) but NOT when I am coasting( foot off gas).
I cant tell where it is coming from, any ideas?????? I'm guessing rear end. No noticeable leaks anywhere. Is this safe to drive????
Are you sure you arent just getting into driving your van so much, your making noises as you drive! vroom, vroom
Or wait, sorry, you said whining, Did you pick Gary up for a ride?
Lol!
 

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Skipping by the humor Bob may have hit it. If the noise continues in neutral while you are moving along without any difference it is not anything in the driveline produced by torque or rpm. Meaning you can probably eliminate any exhaust leaks, transmission or motor causes. But if the noise is really that loud you may have a serious problem and if it is from a bearing it may be on the verge of seizing. If it in fact is coming from the rear end say the spyder gears and that seizes up you can be in for a serious accident. You may want to pull the plug on the rear end housing and dip you little finger in there to see if there is sufficient rear gear oil. If you cant feel it on your finger tip ( a bad thing) the best bet would be to drop the cover have a look and see if there are filings in the bottom of the case. If not( a very good thing) then have someone spin a wheel while the cover plate is off and see if you can see any excessive play. Inspect it well to be sure so you dont have to open it up again. Have a look at the gear teeth. Most noise will come from the teeth not meshing properly. Anyway if it all looks good and you cant see any heat marks then clean the lip and replace the seal along with a liberal use of silicone sealer, fill it with a good rear end lube then take it for a run. If the noise is gone job well done, if not at least one thing has been eliminated and properly serviced.
Keep in mind without the vehicle here in front of us and hearing/listening to it we are all pretty much guessing, just taking a shot. Good luck,

A J
 

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If you remove the pumpkin cover, than may I suggest that the axles come out for inspection, then, even if the axles are good, replace the bearings and seals. Fairly cheap thing to do while it is apart. The axle serves as the inner race for the bearing, and there is a high incidence of damage to the axle with this type of setup, especially when the gear oil level in the pumpkin has been allowed to get low, or the bearing has started to fail on its' own.

Bob

Keep us posted as to what you find/are doing.
 

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Discussion Starter · #12 ·
well I haven't got her up on jacks yet but I did try the neutral thing and the noise definitely follows the engine. It just gets more pronounced when under power(throttle pressed)
At 70 mph it sounds exactly like a weather warning siren (for tornadoes and thunder storms) I mean exactly like it. not as loud of course but the same note.
I'm going to check the rearend fluid level next.
Thanks for all the help so far.
 

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Discussion Starter · #13 ·
One problem exposes another..... I went to check the fluid level in the rear and noticed that the filler plug is striped out.....mmmm... makes me wonder now.
any ideas on how to get this bugger out ? how deep is the filler plug? can I drill into it to get an easy out far enough in . I sure don't want to put metal shavings
in the case if there are none already.
thanks.
 

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Well I would say its time to open up the pumpkin.
While its open, drill out the plug, but stuff a rag or something inside to catch & keep metal dust from spreading around in there.
 

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Discussion Starter · #15 ·
Well I took the cover off today and the gears look like new, no noticeable wear that I can see and no metal shavings anywhere. what do you guys think?
I have got a couple of questions.
1. how much fluid does it take to fill back up. I bought 2- 32oz bottles of 75-90 synthetic gear oil which is what it called for. I was told to use a full bottle and a half.
does this sound right?
2. I bought a new cover and gasket, do I need to use silicon with the gasket or not?
thanks!

 

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Yes, a bottle and a half. No, no silicone with the gasket. I did use gasket tack sparingly just to hold the gasket to the cover while I got the bolts started. Hasn't leaked in almost a year since.

No metal shavings is very good. That wear pattern looks good to me - someone with more experience will chime in.

How did the fluid look and smell (vs new fluid)?
 

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CHEVYKEVYSS said:
well I haven't got her up on jacks yet but I did try the neutral thing and the noise definitely follows the engine. It just gets more pronounced when under power(throttle pressed)
At 70 mph it sounds exactly like a weather warning siren (for tornadoes and thunder storms) I mean exactly like it. not as loud of course but the same note.
I'm going to check the rearend fluid level next.
Thanks for all the help so far.
On 4L60's it's not that rare for the pump to wear out and scream like that.
That will follow engine RPM. The distributor bushing also can make that type of noise.
 

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Discussion Starter · #20 ·
the oil didn't look too bad at all considering it has 100,000 miles on it. What pump are you talking about that may go out?
 
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