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Discussion Starter · #1 ·
Driving from work this afternoon (33 mile drive) get 2 miles from home when i hear a noise while driving down the road and noticed the truck will not accelerate anymore. The engine will rev up but the truck would not speed up like it was in neutral. After about 10 seconds of coasting it decided to start working properly until i reached a stop light. Again no more power to the wheels like it was in neutral. I shifted into park and heard a squeaking/grinding noise. Checked trans fluid it was low, however no visible leaks, no noises while idling, no smoke or anything. Ive shut it off and started it up again, nothing. Shifted through all gears multiple times, still nothing. Itll go into neutral just fine but will not engage in any drive gears. Every time i shift into park with truck running i hear a squeaking/grinding noise and it really concerns me. I would really appreciate some help, i do not have the money to buy a new car or take this to a shop to get it fixed but i do have a garage and basic tools so hopefully i can try and diy it. This is my only vehicle and i need it to get back and forth to work everyday. Please and thank you.
 

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I read you post - kinda - but you stated you have basic tools and a DIY attitude - and that may not be enough. IF what I believe has happened to your transmission, you are in 'way over your head.

But let's look at this for a moment ......

Fluid's LOW (you didn't say if you added any to bring it back up to a normal operating level).​
MAYBE you have the wrong filter in the pan and it finally fell out of the seal and/or it can't suck fluid from the pan because the oil's too low for some unforeseen reason. .​
Maybe.​
Or not.​
I'm not there and you are the eyes and fingers on the scene .... OK?​
It's possible that your convertor blew up - not likely - but possible.​
Squeaking/grinding noises are never good. They are usually from metal-to-metal contact with no lubrication.​
No motion in any gear is troubling.​
Something broke - maybe an input shaft or the front pump - or --- and there's another guy with pretty much the same symptoms --- but his was caused by an alternator failure - so you may just be different.​
My thought here is convertor failure - but that remains to be diagnosed a lot further.​
PS: your transfer case could have slipped into Neutral too.​
We'll have to test more.​
Are you able to do that?​
I ask because of your own confession as to abilities and tools at hand.​
There will be questions.​
 

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Discussion Starter · #3 ·
I read you post - kinda - but you stated you have basic tools and a DIY attitude - and that may not be enough. IF what I believe has happened to your transmission, you are in 'way over your head.

But let's look at this for a moment ......

Fluid's LOW (you didn't say if you added any to bring it back up to a normal operating level).​
MAYBE you have the wrong filter in the pan and it finally fell out of the seal and/or it can't suck fluid from the pan because the oil's too low for some unforeseen reason. .​
Maybe.​
Or not.​
I'm not there and you are the eyes and fingers on the scene .... OK?​
It's possible that your convertor blew up - not likely - but possible.​
Squeaking/grinding noises are never good. They are usually from metal-to-metal contact with no lubrication.​
No motion in any gear is troubling.​
Something broke - maybe an input shaft or the front pump - or --- and there's another guy with pretty much the same symptoms --- but his was caused by an alternator failure - so you may just be different.​
My thought here is convertor failure - but that remains to be diagnosed a lot further.​
PS: your transfer case could have slipped into Neutral too.​
We'll have to test more.​
Are you able to do that?​
I ask because of your own confession as to abilities and tools at hand.​
There will be questions.​
Please, ask any and all questions. I normally work on my own vehicles, oil changes, suspension, brakes, the stuff most people could do with minimal research. The fluid was low, i added 1 quart and it filled it up to the safe level. 4wd doesnt work at all as far as im concerned. Light on dash says service 4wd. The 4wd switch does nothing besides light up as i start the truck. Its stuck in 2wd but i noticed the switch is turned to 4wd auto. Maybe it tried to activate 4wd while driving? Im pretty much clueless when it comes to transmissions but i have a brother who is a mechanic but he lives far away and hasnt given me any advice so far besides check fluid level and try shifting through gears. Im not sure what to do or look for, so ive come here in hopes that someone could give me some ideas.
 

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OK --- I'm gonna copy/paste some of the info I posted on this - as a way to deduce what is going on. Ignore the snide remarks I made in it --- I'm having a boring day and I let my fingers do the talking.

I'm still looking for that article - be patient - I'm old.
 

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Here's the C/P - some of it is not gonna apply - but you'll get the gist of it ....

While your buddy has your vehicle on a rack, make sure he listens to it running first. Ears ... er: trained ears can hear a lot of problems before any judgment is passed.
Check for driveshafts --- are they 1) there? 2) attached? 3) not freewheeling?
If at least the rear driveshaft is there and won't spin with the rear wheels on the ground (parking brake set) ....

...... then proceed to the next step .....

CONFIRM that the transfer case is PHYSICALLY (not necessarily indicated by lights on the dash) ..... at least anywhere but NEUTRAL .... which, coincidentally is electronically controlled ... remembering that you were having alternator-electrical problems FIRST.
Run with this analysis until you are convinced everything up to this point is serviceable....

ONCE it's confirmed the transfer case is OK, proceed to the next gruesome possibility...... the transmission.

Any time a catastrophic transmission failure happens, and unless you hear seriously sinister sounds or see ATF blowing out of the unit, start with basic tests.

The front pump is capable of a quiet death as is the input shaft. Neither give a warning bell and can coincidentally self destruct when your attention is on a different situation.

Once you establish whether you have pressure or not, then either drop the pan to see if you've got a shredded metal collection or black clutches lying in the pan ... or the pan has just a smidgen of corruption (this means less than liquified dust or slight shiny metal flakes in the pan).

If you see chunks of metal, pikes of black ground clutch or ANY BRIGHT PLASTIC PIECES in the pan .... pull the unit for a bench job.
Ditto if you see any remnants of ANY washers .... no matter what they're made of ... in the pan.
Needle bearings, broken or otherwise mean death.

Even if the filter is "just plugged up" the unit is talking to you now. The material sufficient to plug the filter came from things that should be where they were (like clutches, sprags, pinions, bushings), not where they are now (in the filter).
 

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Discussion Starter · #6 ·
Appreciate the reply. This morning before i went to work i decided to mess around with the shifter and eventually got it to actually go in drive. Im no mechanic but that seems like good news to me. Got it to roll forward, stopped, park (heard the same grinding noise when shifting into park as i heard last night, sometimes louder, sometimes quieter) i then gave up and went to work in my other vehicle.

After work i read some other threads and saw someone say pull fuse #8 for 30 sec and put back in to reset something in 4wd system (not sure what) but had no luck. I then got underneath rotated driveshafts, front rotated freely, rear wouldnt rotate at all (its definitely in park). No visible leaks underneath while running or engine off. Absolutely no noise whatsoever from transmission unless shifting into park, can also hear shift linkage moving when shifting through gears. Havent pulled anything apart yet because i dont have it in my garage yet, its currently outside.

After reading some threads on this site about "similar" issues i want to believe it has to do with maybe the transfer case or encoder motor? Maybe even the torque converter? Im no mechanic but i know my truck well enough that there was absolutely no warning when this happened and there are no obvious issues (shaking, noises, or leaks when engine on).

TLDR: With truck running, shifting into R,D,3,2 (will not shift into 1) it acts as if its in neutral, no power to wheels at all. No obvious signs of anything leaking or broken. When shifting into park i hear a squeaking/grinding noise. Got the truck to eventually drive 2 feet then "fell" back out of drive.
 

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I had an issue where the vehicle would pop out of gear and grind until I came to a stop and shifted. Turns out it was a bad encoder motor on the TC. It can be deceptive and make you think it is the trans. Good luck.
 

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There's nothing really to grind in the transmission because there aren't any gears that are shifted into or out of contact. Grinding is from things buzzing/grinding their teeth together - unsuccessfully.

The parking pawl in the notches of the rear planet set can be noisy if it's in motion if you try to go into park ... but no actual grinding.

That's why I asked for the test to put the transmission into any forward gear with the engine running and quickly slam it into Park. If you hear all hell breaks loose, then the transmission if spinning and so is the output shaft and when you put it into park the pawl tries to get into a notch and hold the transmission/vehicle stil.

That noise, by the way - is harmless unless you do it all the time to stop the car that way - but the pawl cannot fall into a notch until things get really slow and then it will stop the output shaft cold.

What all this means is that if somehow there is nothing connected ultimately to the rear wheel (on the ground) then things will spin.
► A spinning component after the output shaft will make it's own special noise.

This is a quickie test to decide if the problem is transmission or transfer case (and further on in the driveline - like a blown differential or missing driveshaft(s) or a blown spider set or a blown axle - etc. ).
 

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Discussion Starter · #9 ·
With the truck running, Ive put the trans in all gears then quickly as well as slowly shifted into park. It definitely makes the same noise. When in a driving gear (Reverse, drive, 2, 3) its a louder grinding/buzzing when shifting into park than when in neutral. In neutral, shifting into park it still makes the noise but its not as loud or fast. Im not sure if it makes sense, but if needed, i can record a video of this. I don't believe its the transmission itself, rather i think its something else. Like i said transmission worked flawlessly until this happened.
 

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OK --- here's some info ....

when you put the transmission into any gear at all - that sets the output shaft spinning because you don't have a connection somewhere further down the line.

Here's a linear flowchart - simplified ....

ENGINE >>
TORQUE CONVERTOR >>​
INPUT SHAFT >>​
CLUTCHES AND DRUMS (it really doesn't matter which ones here since, they will all drag the parts around by fluid stiction anyway) >>​
OUTPUT SHAFT AND THE PARKING NOTCHED WHEEL ON THE OUTPUT SHAFT.​
So-o-o-o when all that stuff is spinning and you put the selector into PARK - the parking pawl (a little 'l-shaped' arm) tries to drop into a notch but they are spinning and until things slow down enough, then it drops into a notch and everything comes to a halt.

56921

PARK PAWL, SPRING & PIVOT


56922


HOW THE PAWL FITS INTO THE NOTCHED WHEEL, ATTACHED TO
THE OUTPUT SHAFT (not in photo)

56923


HERE'S THE 27-SPLINE 4WD THM700 - 4L60 OUTPUT SHAFT.
 
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