Ok my 1999 Tahoe sounds like a loose bolt rolling around in something metal when I take off at low speed, but at high speed I get like a grinding noise when I let off the gas.The transmission seems to be shifting fine and I just had it flushed.I was told it might be the torque converter but I was just checking if anyone has ever had this problem before. Thanks

Ok my 1999 Tahoe sounds like a loose bolt rolling around in something metal when I take off at low speed, but at high speed I get like a grinding noise when I let off the gas.The transmission seems to be shifting fine and I just had it flushed.I was told it might be the torque converter but I was just checking if anyone has ever had this problem before. Thanks


this sound like possible rear diff noises....

how often do you flush the transmission miles??? was the trans filtr replaced ????

this sound like possible rear diff noises....

how often do you flush the transmission miles??? was the trans filtr replaced ????

I just bought the truck and the the fluid was looking pretty nasty.Thats why I had it flushed at Jiffy lube I believe they did the filter.When I hear that grinding I can feel like a vibration through the pedal.the truck has 166k miles on it.

I just bought the truck and the the fluid was looking pretty nasty.Thats why I had it flushed at Jiffy lube I believe they did the filter.When I hear that grinding I can feel like a vibration through the pedal.the truck has 166k miles on it.

I'm goin' with rear end too. But, does the sound continue if you put it into neutral at speed?

Might be a better thing to know what they're gonna' do, before they do it. And ALWAYS make sure WHY they're gonna' do it, and what it DEFINITELY WILL FIX. Not, "We can do this, and that will PROBABLY fix this (since it's 6 years old, or however old)."

You may want to check the u-joints also.

I just bought the truck and the the fluid was looking pretty nasty.Thats why I had it flushed at Jiffy lube I believe they did the filter.When I hear that grinding I can feel like a vibration through the pedal.the truck has 166k miles on it.


on that vibration I would say U joints on the drive shaft..check for throwing rusted grease and play....


since your transmission fluid was contaminated I would call the jif lube and ask how they do this flushing proceedure..step by step... as it is very important to remove the pan and clean then replace the filter,,,,,then start the flushing...


let me know how they do this flushing..

I called Jiffy lube and they said they only hook it it up to a pressurized system they have and that removes 99% of the fluid.(that was a waist of a $100) So I tried reving in neutral while I was driving and I'm not getting that noise so it's only when I'm in drive.It seems like any time above 30pmh I hear it and I'm pretty sure it has something to do w/ the tranny cuz I feel it in the pedal .do u guys think I should have my buddy replace the torque converter and while he's down there clean the pan and change the filter. Thanks

sounds like the front brakes might need checked. anyway i would start there if it were me.

I called Jiffy lube and they said they only hook it it up to a pressurized system they have and that removes 99% of the fluid.(that was a waist of a $100) So I tried reving in neutral while I was driving and I'm not getting that noise so it's only when I'm in drive.It seems like any time above 30pmh I hear it and I'm pretty sure it has something to do w/ the tranny cuz I feel it in the pedal .do u guys think I should have my buddy replace the torque converter and while he's down there clean the pan and change the filter. Thanks

JL cannot remove 99% of the fluid. No one can, without removing the tranny and torque convertor. Ford :shakehead does have a plug in the torque convertor, but Ford sucks. Still ain't gonna' get 99% of Ford fluid either. JL told a lie uh huh.

So you get the sound in drive, but NOT AT ALL, ANYtime in neutral??? 45mph, coast in neutral, and it goes away. Right?

How bout reverse?

I just did new brakes and rotors so thats not it.I do not get the sound at all in neutral. I even went like 60 and threw it in neutral last night and I didn't get the sound, SO it's only when I'm in drive.I'v never heard it in reverse but then I'v never went that fast in reverse only pulling out of my driveway.

I called Jiffy lube and they said they only hook it it up to a pressurized system they have and that removes 99% of the fluid.(that was a waist of a $100) So I tried reving in neutral while I was driving and I'm not getting that noise so it's only when I'm in drive.It seems like any time above 30pmh I hear it and I'm pretty sure it has something to do w/ the tranny cuz I feel it in the pedal .do u guys think I should have my buddy replace the torque converter and while he's down there clean the pan and change the filter. Thanks

I'm sorry to hear that your transmission service was not done correctly....this is how to destroy a transmission by power flushing with out the replacement of filter and not cleaning the debris in the pan bottom...


very soon before things get damaged drop pan and replace filter and keep fingers crossed..

I had this noise before I did the flush.I'm gonna drop and clean the pan and change the filter.But do you guys still think it can be the torque converter?

Transmission flushes are huge waste of money and do not ever get one done.All I hear are horror stories after a transmission was flushed.If you want to spem money on a valve body cleaning or rebuild,flush it.Where I work,My father and I do not flush an automatic transmission at all,change the fluid and filter with NO comebacks.We know about it,a transmission shop down the road we are "allies" with does lots of valve body cleanings and rebuilds due to flushes with the machine.It could be the rear planetery gears out which a rebuild is needed.If this is the case,the cooler in the radatior is bad

I just tried out 4 wheel HI and I'm getting that grinding noise the whole time I'm in 4hi.So would that be the rear end?

Pulll the rear driveshaft and the tailshaft cover off the transfer case.Look for a broken snap ring,in 2 or 3 pieces and this is a common problem.

Pulll the rear driveshaft and the tailshaft cover off the transfer case.Look for a broken snap ring,in 2 or 3 pieces and this is a common problem.

If this is the case, it wouldn't make a difference Drive or Neutral, would it?

With his, it is making a difference...

???

I have seen this happen in a 1998 GMC truck.Thought it was in the transmission and it was not finding broken parts inside.Pulled the cover off the tailhousing of the transfer case finding a broken snap ring.

Pulll the rear driveshaft and the tailshaft cover off the transfer case.Look for a broken snap ring,in 2 or 3 pieces and this is a common problem.

I was just reading up on this snap ring too.I'm gonna pull that apart tonight or tomarrow and let you know what I see.Thanks for the help

I bet it could be your transfer case. The transfer case halves are magnesium on the NP246 model. The gear that pumps the fluid inside wears a "pin size hole" through the outer case half. This causes your fluid to leak slowly and if not kept up, will cause the transfer case to burn up completely. These case halves are very hard to find. Tranny shops will not be able to rebuild your transfer case w/out another case half. Plus, GM has not fixed this issue with the oil pump wearing holes into the transfer case. Tranny shops do offer an elimenator kit that prevents this from happening in the future after a rebuilt. Your looking at anywhere from $800 to $1200 if this is the case. If your transfer case looks like it has a leak look for a pin sized hole on the bottom of the case on the back half of the trasfer case where the rear drive shaft connects. Good luck. If this vibration is from the transfer case this can cause the tranny to go bad if not taken care of in a timely fashion.

P.S. This has happened to me.

Well good thing I just picked up a whole transfer case from my buddy for $200 on Friday.(He really needed money)But I'm gonna have him drop the transfer case and look inside and if it's too bad I just swap it.Or if its fixable I'll just fix and keep the other one on the side

I bet it could be your transfer case. The transfer case halves are magnesium on the NP246 model. The gear that pumps the fluid inside wears a "pin size hole" through the outer case half.

The gear inside wears a hole in the transfer case???

The gear inside wears a hole in the transfer case???

Yeah I guess it constantly rubs or vibrates against the case eventually wearing a hole in it. I went to three different tranny shops none of which had a case half to use for the rebuild & said it could be a while before they find a used one without a hole in it. When I asked if the hole could be welded they looked at me funny. I dont know if magnesium cant be welded? Anyways they put a steel plate inside to prevent this from happening. Transfercase models NP246 Autotrac have these issues. The outer casing is magnesium.

Well good thing I just picked up a whole transfer case from my buddy for $200 on Friday.(He really needed money)But I'm gonna have him drop the transfer case and look inside and if it's too bad I just swap it.Or if its fixable I'll just fix and keep the other one on the side

Hey does your tahoe have the Autotrac in it? If so, the transfer case needs a special fluid called "SYNCROMESH". Its blue in color. You can get it at your local chevy dealer. It's about $14 a quart. Or you can use Royal Purples version called "SYNCROMAX". Same stuff but its only $10 a quart. Dont use normal tranny fluid in these transfer cases(np246).

Hey does your tahoe have the Autotrac in it? If so, the transfer case needs a special fluid called "SYNCROMESH". Its blue in color. You can get it at your local chevy dealer. It's about $14 a quart. Or you can use Royal Purples version called "SYNCROMAX". Same stuff but its only $10 a quart. Dont use normal tranny fluid in these transfer cases(np246).


I believe the transfercase fluid is called trac II transfer case fluid made only by GM...only available at dealer...last purchased for 6.oo /qt.. will need 3quarts...actually 2.5qts the fluid is blue when new the fluid needs replacing when it turns gray ...If the fluid is black get your wallet ready..

Yes my Tahoe does have the auto trac(good looking on the fluid info).I still havent got around to dropping the t case yet I had a busy weekend.I'm gonna try to start on it tomarrow I really wanna find out what it is.Once again thanks for all the help and as soon as I drop it I'll let you guys know what happend.

It is called GM Autotrak II fluid, P/N 12378508, and I was quoted $7.69/qt back in the summer.

Quick ? I just dropped the transfer case and does anyone know what size the allen wrench is for the fill plug and how the hell do you fill it once you put the transfer case in?

Quick ? I just dropped the transfer case and does anyone know what size the allen wrench is for the fill plug and how the hell do you fill it once you put the transfer case in?


i used a metric allen wrench set ....forgot what size..but you can use the head of a bolt ....

to fill you use a qt bottle hand pumper ....this pumper is very handy to fill the other under vehicle componets..


I use mineral spirits to flush out and clean after use...

if it's not one thing it's another. ok I just finished putting the transfer case in took it for a test drive and no noise when I was driving but when I put it 4hi it stays there and wont come out and my service 4wheel light came on. any ideas?

Well I just turned the truck off and then I can switch back to 2wd.If im in neutral not movind I can put in 4hi,4lo and auto but if I leave in 4hi and start driving thats when my service 4wd light comes on and won't shift back 2wd.I' disconnected the battery and I tryed pulling the fuse.:banghead:

Well I just turned the truck off and then I can switch back to 2wd.If im in neutral not movind I can put in 4hi,4lo and auto but if I leave in 4hi and start driving thats when my service 4wd light comes on and won't shift back 2wd.I' disconnected the battery and I tryed pulling the fuse.:banghead:

you will need dtc for this ,,so that we can get to whats going on exactly.... It could be the encoder motor binding...you go 2 motors so you could swap out...

what color was the transfer case fluid that you drained out..did it look dark/black gray...???

as you know don't drive far on solid dry pavement in 4X4 or auto because you will rapidly damage the drive train componets...

The color in my old one was red witch who ever had it b4 me put the wrong one in cuz it's the 246gm.But the one I put in had the blue fluid and thats what I also put in.

The color in my old one was red witch who ever had it b4 me put the wrong one in cuz it's the 246gm.But the one I put in had the blue fluid and thats what I also put in.


these 99 on up transfer cases require the trac II fluid...many still believe that it can be substuited with transmission fluid....this is what happens when you use the wrong fluid in these transfer cases...


so thanks for that info.... this will help others, so that they will NOT use the wrong fluid..

I 've found this failure of the case or tranfercase internally breaking up from this improper fluid use...[transmission fluid is cheaper]

you will need dtc for this ,,so that we can get to whats going on exactly.... It could be the encoder motor binding...you go 2 motors so you could swap out...

what color was the transfer case fluid that you drained out..did it look dark/black gray...???

as you know don't drive far on solid dry pavement in 4X4 or auto because you will rapidly damage the drive train componets...


Could I swap these motors w/ out draing the transfer case?

Could I swap these motors w/ out draing the transfer case?

I don't see you can't .the motor is above the fill hole...