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4wd problem? deceleration wail - '97 blazer 4x4

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4wd problem? deceleration wail - '97 blazer 4x4 - 2/3/2006 5:27:48 AM   
magtec

 

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i'm experiencing what appears to be a problem with my '97 blazer's 4wd system. when in 2-high and decelerating from highway speeds (65+ mph) it will sometimes begin to wail and drag like it's in 4wd (think of an air raid siren, the sound is very similiar and very loud). at that point if i keep it moving above a few miles per hour, the 4wd seems to stay engaged. if i slow down far enough that the truck almost stops, the noise and drag disappear and everything seems normal.

also, when purposely switching to 4wd it sometimes will not disengage until i shut off the engine.


edit:
just a side note: i think it's going into 4-low on the highway. i haven't played around too much, but the sound 4-high makes is very similar but not nearly as loud as what happens when it randomly engages.

< Message edited by magtec -- 2/3/2006 5:31:32 AM >
Post #: 1
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/3/2006 3:32:34 PM   
magtec

 

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Joined: 2/2/2006
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if anyone has any ideas at all, please share. i hate to bump this thread to the top again, but i do 200+ miles per week of highway driving.

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to magtec)
Post #: 2
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/4/2006 3:21:17 AM   
magtec

 

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Joined: 2/2/2006
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here's an easier question: if i yank fuse #19 will that disable 4wd for testing purposes?

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to magtec)
Post #: 3
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/4/2006 3:25:21 AM   
4lowlife



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Are you driving in 4WD 65mph+?
If it's in park and engine running, will it fully shift into 4wd? And not blink?

< Message edited by 4lowlife -- 2/4/2006 3:33:25 AM >

(in reply to magtec)
Post #: 4
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/4/2006 3:49:53 AM   
magtec

 

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Joined: 2/2/2006
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i am not purposely driving in 4wd. whatever it's doing, it's doing it by itself upon deceleration. in fact, the 2high light stays lit when it happens, but it sounds and drags like 4wd.

in park with the engine running it will shift into 4high and 4low and not blink (and sometimes will not disengage until the engine is turned off).

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to 4lowlife)
Post #: 5
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/4/2006 4:25:42 AM   
4lowlife



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Parking brake not sticking right?
Will the transmission shift normal in acceleration?
So you do not feel nor hear anything upon accerating? Just trying to narrow down whats going on here.
I wonder if its downshifting too early. Does the tach jump up RPM's when you are off the throttle?

(in reply to magtec)
Post #: 6
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/4/2006 1:05:53 PM   
magtec

 

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Joined: 2/2/2006
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the parking brake light isn't on, but i haven't checked the brake to see if it's on.

haven't noticed the transmission shifting abnormally. it seems to shift great.

i do not feel or hear anything upon acceleration, but the moment i let off the accelerator at roughly 65+ mph, it starts to wail like it's in 4wd and will continue to make the noise unless the truck slows down to a few miles per hour at which point the noise and drag vanish (sometimes with a thud/thump).

i'll have to keep an eye on the tach next time it happens, but it doesn't seem to be downshifting early and iirc, it's only at about 2k rpm when it happens.


edit:
i'm probably not describing the problem very well, but i don't know how else to describe it. maybe it's not going into 4low. the noise it makes sounds like the same noise that 4high makes, only much louder. it sounds quite a bit like an air raid siren going from high to low frequencies. it also sounds kind of like road noise from deep tread tires, but if it's road noise, why does it only happen when decelerating from 65+ mph, and why would it then continue to make the noise down to roughly 3mph?

< Message edited by magtec -- 2/4/2006 1:18:16 PM >


_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to 4lowlife)
Post #: 7
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/4/2006 2:38:39 PM   
magtec

 

Posts: 167
Joined: 2/2/2006
Status: offline
here's some new information: if i hit the 4high button while it's making the noise, the 4wd engages and the noise stops. so apparently it's not going into 4wd while decelerating, but the noise has something to do with the 4wd system.

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to magtec)
Post #: 8
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/4/2006 7:49:39 PM   
magtec

 

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Joined: 2/2/2006
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and a little more information: it seems to only happen under very specific conditions. based on my testing, it seems i have to be going uphill in third (at roughly 65mph), then let off on the accelerator for it to make the noise. i can't make it happen every time i try, but there's one point on my way to work where it happens almost every drive if i'm going fast enough.

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to magtec)
Post #: 9
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/5/2006 4:14:35 PM   
magtec

 

Posts: 167
Joined: 2/2/2006
Status: offline
is there anything else i can add to this that would help with diagnosis or troubleshooting?


edit:
someone in another forum mentioned that some of the blazers had 'soft' spider gears that would cause a howl over 35mph unless 4wd was engaged. can anyone get a hold of a tsb for this?

< Message edited by magtec -- 2/5/2006 10:36:44 PM >


_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to magtec)
Post #: 10
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/6/2006 6:01:11 PM   
Paddle_grl


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Joined: 9/10/2005
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well here's my 2 cents...does it happen all the time? if you hit the 4wd then the 2wd button...does that make it stop? my suggestion is the transmission....there's a gear....after a while...there's no more grip..and no more transmission...it's personal experience...(sorry I can't explain it in technical terms)


_____________________________

dirty girls rule!!!!!


(in reply to magtec)
Post #: 11
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/6/2006 7:29:06 PM   
magtec

 

Posts: 167
Joined: 2/2/2006
Status: offline
no, it does not happen all the time. it only happens under very specific conditions.

the 4wd will not disengage unless the engine is shut off, so i cannot answer your second question.

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to Paddle_grl)
Post #: 12
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 2/6/2006 7:54:45 PM   
Paddle_grl


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well the reason I asked..I have a 200o blazer...and for about a year...when ever the cruize had been on for a while..and I'd step on the brakes..or slow down..to exit.or what ever...I would hear this horrible..I thought more of a grinding sound..but it was kind of wailing too...well no one could figure out what was wrong..and it would only happen in senarios similar...soooooo.....I used to be able to hit the 4wd button..and then 2wd and fixed the issue...sometimes I would have to pull off and put it in reverse....long story short...one day I went to step on the accelerator and there was no acceleration...and then I lost reverse....ended up needing a new transmission....it was a gear in the blazer transmission...I guess you can replace the gear before the whole thing blows....I got a used one for not too much money......

_____________________________

dirty girls rule!!!!!


(in reply to magtec)
Post #: 13
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 3/29/2006 5:18:21 PM   
magtec

 

Posts: 167
Joined: 2/2/2006
Status: offline
anymore input on this problem before i dig into the transfer case?

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to Paddle_grl)
Post #: 14
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 5/24/2006 9:50:56 AM   
st_pinetree

 

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Joined: 3/19/2006
Status: offline
I found this thread during a search, so am bumping it up. I am having the exact same issues. Anyone add anything new? A significant grinding/howling sound on decelleration, only occurs occasionally, and goes away if you hit the 4 wd button. I am theroizing that maybe the solenoid that engaged either the axle or transfer case is partially engaging on its own for some reason, but its pure speculation.

Thanks!

(in reply to magtec)
Post #: 15
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 5/24/2006 8:58:23 PM   
quontush

 

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i know exactly what it is, i think, haha anyway i had this very same problem, it was the vacume switch that engaged the front differental
could be two things
1) the actuall switch here is a link to that vacuume switch -that is one online, i needed one right then and paid $40 from a dealer
how to get to it--- under the car on the transfer case this screws into the top( its on the drivers side) this is what it looks like with the tube on to pic
and that can be found HERE
u may need a new one of those or :
2) or may need this:actuator That is found underneather the batterie and the box it sits in. The bolts for that are acseeable from the wheel well

3) or both or the cable that ataches to the actuator,but i doubt that sence this only happens sometimes

hope that helps you , sorry for the errors in the typing its my first real right up of a fix for a problem

_____________________________

95 4wd 4 door 4.3 auto---- sold

(in reply to st_pinetree)
Post #: 16
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 5/24/2006 11:15:55 PM   
Bojib


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Joined: 11/21/2005
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What quantosh said.

I had the same problem with mine, and it wound up just being the vacuum switch on the transfer case.

(in reply to quontush)
Post #: 17
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 5/24/2006 11:50:10 PM   
Paddle_grl


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by the way if you don't fix it...you will need a new transmission.....it will wear your little gear down until it's gone....

_____________________________

dirty girls rule!!!!!


(in reply to Bojib)
Post #: 18
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 5/25/2006 5:03:05 AM   
magtec

 

Posts: 167
Joined: 2/2/2006
Status: offline
still haven't determined what the problem is. i thought i fixed it by reconnecting a vacuum line in the dash, but the problem is still there - it just doesn't happen as often (could be the fact that the weather is warmer now). it has been kind of rainy lately, so i haven't had a chance to check things out.

_____________________________

  '89 acclaim - 2.5 turbo, a520
  '88 lancer shelby - 2.2 turbo II, a555
  '97 blazer ls - 4.3 vortec, 4l60e, 4wd
past:
  '87 lebaron gts - 2.2 turbo, a413
  '87 lebaron gts - '85 2.2 turbo, a413
  '88 s10 blazer - 2.8, 5-speed

(in reply to magtec)
Post #: 19
RE: 4wd problem? deceleration wail - '97 blazer 4x4 - 5/25/2006 11:13:03 AM   
st_pinetree

 

Posts: 9
Joined: 3/19/2006
Status: offline
Thanks guys, I am fairly certain its the vaccuum switch on the t-case. I will pick one up today and give it a whirl. Problem is, the syptoms are so random I'm not going to be comfortable that it is or isn't fixed for quite some time. I will try to remember to report back.

Thanks again for all your input.

(in reply to magtec)
Post #: 20
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