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2003 chevy trailblazer_ls
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Discussion Starter #1
Hey everyone, I have been combing through all the forums on this website looking for help and now im finding myself needing help on trying to figure out how to start a non-introduction thread. My name is Marc I have over 10 years of experience working on vehicles anything that has a motor, veteran of the NAVY as a Machinest mate, and now I work for the leading automotive reseach facility in the world. I have a 2003 Trailblazer ls 4.2L L6 that has roughly 214,000 miles on it that i have been constantly working on. Changing everything from water pump, adding HID lights, stereo system, back up camera, motor mounts, EVERY ball joint and bushing, read axle, seals, muffler, etc... and I live in Soutwest Virginia. Mainly I have been trying to diagnose my vehicle issues with family, friends, "experts" of the field and need some help from a broad community of enthusiasts.
 

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2003 chevy trailblazer_ls
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Discussion Starter #3
Welcome, and thank you for your service.

What problem(s) are you having?
On my 03 Trailblazer, after replacing the water pump and radiator(because i broke the pipe nipple when taking out the fan clutch and shroud) i was driving down a hilly bending road and the trailblazer slammed internally. Ever since i can only get it to shift going from 1st to 2nd by driving to atleast 17mph and letting my foot of the gas, then it will engage into second. Along the same lines i also noticed it wont stay in 4th(overdrive) on the highways. It will engage 4th/overdrive only and if i let my foot off the gas to let it coast, but as soon as i hit the gas it drops to 3rd. and not lastly for instance if im trying to speed up in a hurry it will slam from 3rd to second on the highway. Sorry if this is confusing ive been having this issue over 2 years and have never had so many issues diagnosing a issue. I changed the transmission solinoids and throttle body(TPS inside) will no changes to the issue from other people recomandations.
 

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2003 chevy trailblazer_ls
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Discussion Starter #5
Sounds like you need a diagnosis at a transmission shop.
I brought it to two seperate transmissions shops that had two different diagnoses. But both recomended a transmission rebuild that I already had rebuilt 35,000 miles ago. The trailblazer is in a "limp mode" which prevents the car from damaging itself. My biggest issue is that GM/Chevy has combined several electrical components together creating an eletrical issue almost impossible to diagnose especially when noone else seems to have the same issue or they do on here but noone has replied to the thread. But thank you for your input. Do you know how i can create a thread outside of the introductions?
 

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2004 gmc envoy_slt
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Do you know how i can create a thread outside of the introductions?

Click on Forums at top of main page, then select 02 -09 Trailvoy Tech, select any thread category, then click on New Thread at top left.
 

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I recognize that this is almost a zombie thread - but I don't see a resolution to it.
Does ANYONE ever follow up with success or failure stories?

To the OP: your symptoms are usually accompanied with the exchange of large sums of money.

AS I SEE THE PROBLEM: I'd drop the pan FIRST ---> but I'm sure you'll find pieces of stator support seals and/or bushings in the mud in the bottom of the pan.
The front pump has usually taken it in the shorts by now too - but that is another 'expected' condition for a rebuild.

We tend to call a job like this a "Grenade".

Rebuild time
. 🥴

I don't see how a real transmission shop didn't offer to drop the pan for a look-see in the first place. If this came into MY shop, I'd offer the exploratory for free pending the diagnosis and rebuild.
You have a fairly common situation when the transmission hasn't been taken care of by the previous owner(s). It's too late for a service since it will not put metal on parts nor clean out the metal that is dirtying the rest of the unit.

The symptoms are kinda condemnatory at least and after the pan drop, all else is just shuffling chairs on The Titanic.
The unit HAS to come out even if this is just for a front pump or minor interior repair.
You cannot push parts through the side of the case - so just pull it and throw it on the bench.
New parts do NOT come in fresh cans of ATF or magical elixirs either.

BTW: be ready to replace the radiator as you won't be able to clean the heat exchanger.
  • Notice I called it a "heat exchanger" because it is NOT a fluid cooler.
  • Your unit needs 180F fluids temperature for it to work correctly.
  • That the ATF flows through an item inside the radiator that itself is 180-210F should tell you that the trans is designed to run at those temps.
Just adding an external cooler will create problems when the plasticizers in the ATF cannot 'work' and prolong the rubber parts that are used as seals, o-rings and other parts that need the fluid to 'treat' them.

Make sure you get a "Worst Case" estimate - which usually has a rebuildable core charge for another unit that can be rebuilt instead of yours.
  • I never charge for core units and I even build a few in advance for situations like yours.
  • I'm always buying junkyard used units and going through them and holding off on the valve body until I see the calibration of the unit it is going to replace.
  • But that's just me and MY shop.
  • Others don't/won't give a bag of snot about time and circumstances in your situation.
  • Don't forget to factor in a new radiator - because it will metal-out a new unit quickly ---> even WITH in-line, magnetic filters.
  • They help, but are not a preventative measure..
  • I have yet to see a successful clean out of a heat exchanger in a radiator without a whole new radiator or IF you can find a shop with the correct gear to disassemble your radiator and install a new exchanger.
Just sayin'............
 

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2003 chevy trailblazer_ls
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Discussion Starter #9
I recognize that this is almost a zombie thread - but I don't see a resolution to it.
Does ANYONE ever follow up with success or failure stories?

To the OP: your symptoms are usually accompanied with the exchange of large sums of money.

AS I SEE THE PROBLEM: I'd drop the pan FIRST ---> but I'm sure you'll find pieces of stator support seals and/or bushings in the mud in the bottom of the pan.
The front pump has usually taken it in the shorts by now too - but that is another 'expected' condition for a rebuild.

We tend to call a job like this a "Grenade".

Rebuild time. 🥴

I don't see how a real transmission shop didn't offer to drop the pan for a look-see in the first place. If this came into MY shop, I'd offer the exploratory for free pending the diagnosis and rebuild.
You have a fairly common situation when the transmission hasn't been taken care of by the previous owner(s). It's too late for a service since it will not put metal on parts nor clean out the metal that is dirtying the rest of the unit.

The symptoms are kinda condemnatory at least and after the pan drop, all else is just shuffling chairs on The Titanic.
The unit HAS to come out even if this is just for a front pump or minor interior repair.
You cannot push parts through the side of the case - so just pull it and throw it on the bench.
New parts do NOT come in fresh cans of ATF or magical elixirs either.

BTW: be ready to replace the radiator as you won't be able to clean the heat exchanger.
  • Notice I called it a "heat exchanger" because it is NOT a fluid cooler.
  • Your unit needs 180F fluids temperature for it to work correctly.
  • That the ATF flows through an item inside the radiator that itself is 180-210F should tell you that the trans is designed to run at those temps.
Just adding an external cooler will create problems when the plasticizers in the ATF cannot 'work' and prolong the rubber parts that are used as seals, o-rings and other parts that need the fluid to 'treat' them.

Make sure you get a "Worst Case" estimate - which usually has a rebuildable core charge for another unit that can be rebuilt instead of yours.
  • I never charge for core units and I even build a few in advance for situations like yours.
  • I'm always buying junkyard used units and going through them and holding off on the valve body until I see the calibration of the unit it is going to replace.
  • But that's just me and MY shop.
  • Others don't/won't give a bag of snot about time and circumstances in your situation.
  • Don't forget to factor in a new radiator - because it will metal-out a new unit quickly ---> even WITH in-line, magnetic filters.
  • They help, but are not a preventative measure..
  • I have yet to see a successful clean out of a heat exchanger in a radiator without a whole new radiator or IF you can find a shop with the correct gear to disassemble your radiator and install a new exchanger.
Just sayin'............
Hey Ravalli,

Thanks for giving the time and writing all of that, I have dropped the pan several times checking for metal shaving and replacing solenoids. When I replaced the radiator (because i accidentally broke the nipple off of the old one by taking out the fan clutch, I flushed out the new one prior to installataion. But overall i did not find anything out of the ordinary inside the trasnmission pan, and the further I research with no absolute soloution the more i am leaning towards a "limp mode" but with chevorlet especially trying to find an electrical issue with one of their many sensors is near impossible since i cant find someone that has similiar issues with quaranteed results.
 

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Hey Ravalli,

Thanks for giving the time and writing all of that, I have dropped the pan several times checking for metal shaving and replacing solenoids. When I replaced the radiator (because i accidentally broke the nipple off of the old one by taking out the fan clutch, I flushed out the new one prior to installataion. But overall i did not find anything out of the ordinary inside the trasnmission pan, and the further I research with no absolute soloution the more i am leaning towards a "limp mode" but with chevorlet especially trying to find an electrical issue with one of their many sensors is near impossible since i cant find someone that has similiar issues with quaranteed results.
Thanks for the reply.

I'm not THERE where you are and I have little more to go upon than what you say and what I can imagine in hopes that you get this problem settled and repaired.

I suspect that you might not have just a control problem, since your symptoms are seemingly confusing and you don't think there's a common or singular path to fixing this unit.

Here's my take----> look carefully at any transmission shop you might choose to do the repair. They should not be one of the big chains (HINT: lots of "A"s in the name) and you need to make sure that they understand your concern that it will not be repaired correctly - or at all.

You need more of a 'mom-n-pop' store with open bays where you can actually see work being performed on other vehicles.

I never hired a service writer for my shops. I made sure that the customers always had their job defined and decided upon by the owner (me) or one of my mechanics.

If they won't let you talk to the bench-guy (he actually builds and repairs your unit) - then walk out. That's not the shop you want.

I always like to have customers like you since I can fix their unit and then charge tham less than the original estimate. That makes people happy.

I'm retired now and don't do any side work, but I haunt a few friendly transmission shops where I live - and believe me that most of them I would not run into if I was on fire needing someone to urinate on me.

I feel sorry for people like you who get too many opinions and seemingly expert advice.... and I'm no better since I am the worst as I am nowhere near your unit. Right now you are playing Whack-A-Mole and just trying to win once more.

OH -- BTW: any rebuilt transmission that fails at 35K miles was not done correctly. Stay outta the place that did that to you last time. .

Find one shop and trust them to make it right... and again I say:

  • NO DEALERS,
  • NO NATIONAL CHAINS AND CERTAINLY.........
  • DO NO GOT TO SOMEONE WHO PROVIDES REBUILT UNITS ON AN EXCHANGE BASIS FROM SOME OTHER REBUILDER.
Really - the guy who installs your unit is the most dangerous guy in the shop.

For that I apologize.
 

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Does sound like his has a good deal of probs but the problem with almost all trans shops is all they want to do is rebuild your unit for the big ticket price.
GMs can be in limp mode and only need a solenoid and stuck in 3rd and they would still tell you it's toast and needs rebuilt.
Hard to find an honest, non-greedy trans shop.

I just stay away. If I can't fix it I will just get a good used one and swap it out.
Same for engines.
These shops should be ashamed to recommend an engine replacement of 4500-6000 on a 15-20 year old car.
 
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