What did you do to your GMT today?

HARDTRAILZ

Moderator
Loading it up to take stuff to the farm for last weekend of deer season. Bunch of jugs of water since the main system is winterized and some cooking apparatus to have some people over in evenings and enjoy some tasty treats.
 

Maverick6587

Well-Known Member
Another note from the new to me 9-7x troubleshooting, that I just could not leave out because I laughed about for a little bit and still find it very amusing as I'm writing this.

The guy said he was an ASE mechanic... After I fixed the UCA I took it for a little test drive down the road a few miles. Got back into the driveway to hear a boiling noise and immediately remembered @TequilaWarrior's post about how he boiled brake fluid.

On inspection of the master cylinder to see if the fluid was boiling. I notice that this ASE mechanic had placed a plastic bag in between the cap and the mastery cylinder. The cap does not catch, to stop turning.

I didn't have time to look and see if the cap itself was broke or the master cylinder. So, I have to figure that out as well. My guess with my luck is it's the master cylinder and someone probably tightened the cap too tight and broke it.
 

TequilaWarrior

Well-Known Member
Another note from the new to me 9-7x troubleshooting, that I just could not leave out because I laughed about for a little bit and still find it very amusing as I'm writing this.

The guy said he was an ASE mechanic... After I fixed the UCA I took it for a little test drive down the road a few miles. Got back into the driveway to hear a boiling noise and immediately remembered @TequilaWarrior's post about how he boiled brake fluid.

On inspection of the master cylinder to see if the fluid was boiling. I notice that this ASE mechanic had placed a plastic bag in between the cap and the mastery cylinder. The cap does not catch, to stop turning.

I didn't have time to look and see if the cap itself was broke or the master cylinder. So, I have to figure that out as well. My guess with my luck is it's the master cylinder and someone probably tightened the cap too tight and broke it.
Just a quick note ... brake fluid boils in the caliper and creates a vapor space. That vapor space is what causes the extremely "spongey" brake feel. It also dramatically decreases heat transfer to the fluid. So what happens is the heat boils the fluid which creates the vapor space pushing fluid backwards in the line (and away from the heat). The vapor remains until it drops below it's condensation point (which takes forever since it's in contact with the heated portion of the caliper). While the vapor space exists, if the brakes are applied it compresses the gas in the vapor space (whereas the fluid is not compressable) which makes the feel "spongey" and the pressure inside the caliper no longer gets high enough to push the piston to the pad with any meaningful force - thus, you get a loss of braking. If you've boiled brake fluid, do a brake flush.

The boiling you heard - unless you had a spongey brake pedal - was most likely engine oil, but possibly transmission fluid, especially if you are missing the heatshield from your exhaust manifold or catalytic converter. The noise you heard, if it was "percolating" type noise, is one I've heard and each time it came down to engine oil for me.
 

Mooseman

Moderator
Found a deal I could NOT pass up on! 2007 9-7x 5.3 with 230k miles on it for $850.
Nice find! I'm not familiar with those wheels. Maybe from a Rainier? They do look nice on it. Keep an eye on the infamous rust on the front of the hood. Look for my thread on fitting aftermarket HID ballasts as the originals are oh so expensive if they need replacement. Oh, and get a tune!
 

Maverick6587

Well-Known Member
Nice find! I'm not familiar with those wheels. Maybe from a Rainier? They do look nice on it. Keep an eye on the infamous rust on the front of the hood. Look for my thread on fitting aftermarket HID ballasts as the originals are oh so expensive if they need replacement. Oh, and get a tune!
I luckily found a decent 9-7x hood at the junkyard a few weeks ago that I've been working on getting it rust free and painted, now I can add a bumper cover to that paint list. I found your HID thread, thanks! I waited until I got home to really "give it some gas", that 5.3 really has some power with AWD! I'll either get a hold of limequat or play around with HDTune.
 

Maverick6587

Well-Known Member
The boiling you heard - unless you had a spongey brake pedal - was most likely engine oil, but possibly transmission fluid, especially if you are missing the heatshield from your exhaust manifold or catalytic converter. The noise you heard, if it was "percolating" type noise, is one I've heard and each time it came down to engine oil for me.
Thank you for the detailed explanation! Honestly, I'm not 100% sure it was the brake fluid, just fairly sure. The brakes are very light/spongy. I could feel the boiling coming from the front left floor board. I assumed I was feeling the boiling in the brake lines.

I do plan to swap out the master cylinder and do a complete brake fluid flush this weekend. The plan is to flush as many fluid systems I can this weekend. Transfer case and differentials are 2nd priority to the brake fluid and and engine oil. I might be able to get to do the transmission and coolant. I'll probably find something in horribly wrong along the way and only get the brake fluid and engine oil changed though.
 

TequilaWarrior

Well-Known Member
Thank you for the detailed explanation! Honestly, I'm not 100% sure it was the brake fluid, just fairly sure. The brakes are very light/spongy. I could feel the boiling coming from the front left floor board. I assumed I was feeling the boiling in the brake lines.

I do plan to swap out the master cylinder and do a complete brake fluid flush this weekend. The plan is to flush as many fluid systems I can this weekend. Transfer case and differentials are 2nd priority to the brake fluid and and engine oil. I might be able to get to do the transmission and coolant. I'll probably find something in horribly wrong along the way and only get the brake fluid and engine oil changed though.
I know you had replied to my thread regarding brake flush so you're more than likely already aware of the lessons I learned the hard way. Also, I was surprised at the improvement of my transmission after my tranny fluid flush - the hardest part of which was knowing when to stop as I didn't have a graduated container. Good luck.
 

Maverick6587

Well-Known Member
@TequilaWarrior Yeah, I'm hoping to change the transmission fluid and filter this weekend. At least most of the fluid. I'm not 100 sure I'm going to do a complete flush or just a drain from the pan. I've heard of transmission problems happening after a complete flush.
 

Drec

Well-Known Member
After replacing the Envoy catalytic convertor and O2 sensors, during the drive cycle all of the monitors completed, except for the EVAP; which finally reset after about 700 miles. So it is probably in the best shape it has been in since I’ve owned it (2years) and 35K miles.
 

Mounce

Well-Known Member
Drove her home. Found this morning that the same reverse bar fell off again... Very odd, haven't looked yet but I imagine it snapped the screw off again, pretty sure I didn't over tighten this one but whatever. Time to buy some bigger self tappers and be done with it. Zip tied it up and zipped 400 miles home, will tinker with it Sunday. Averaged a little over 16mpg which is excellent for my truck, highest I've seen.
 

Beacon

Silver Supporter
Minor headlight lens restoration, I didn't use sandpaper, just Meguiar's ultimate compound and then polish. I wanted to take before and after pics for my own comparison, and left the house without my phone. :bonk: But, I'm happy with the results, almost like new.
0103201953.jpg
 

Mooseman

Moderator
Replaced the cluster and steering column with those from an LT so I can have a DIC and nice leather wheel. Didn't quite finish it all, have some wiring to finish to the cluster from the steering. I had tried to reprogram the cluster to an 06 LT, the only year that did have Stabilitrak but not TPMS. Thinking that if it's not programmed for it, it will ignore the signals from the BCM/LGM about it. Well, that didn't work as the error and light still showed its ugly head. I tried a cluster from an 05 Envoy. No TPMS error but no Stabilitrak indicator or message neither. Oh well, I'll keep an eye out for an 06 LT or Envoy (like the Voy's gauge face better).

Tomorrow, I'll finish up the wiring and if I have time, also swap the key cylinder and sensor from the old column. It's giving me the security error light but since I had VATS disabled in the PCM, it still starts. Or I could try to reprogram the BCM/VATS.

Getting the radio controls to work will be a whole other story as that normally goes to the BCM and then it sends the commands to the radio. Unfortunately, I will not be able to use the interface that @xavierny25 sent me. Might have to try and use the two wires on my Android HU connected directly to the column buttons' two resistance wires.

I might do a write up on all this.
 

Eric04

Silver Supporter
On today's episode of This Old Truck: After returning from the alignment I noticed a smell like something was burning. By this time any residual errant shots of Blaster should've been vaporized so... I looked around at the time and upon feeling the rims noticed the passenger side could fry an egg. I threw a new set of pads on while I was in the neighborhood rebuilding the front end, figuring on doing more brakes later as everything else looked okay. Apparently the caliper is lazy. Yay.

Fortunately I had not tossed the old pads in the roll away, only in the bin in the garage. Fished them out today, cleaned them up and reinstalled them. Took it for a test drive with several stops and no more hot rim. I've already got calipers, hoses, and new front rotors on the way. I planned on doing this job later this year anyway given the age of the truck but the TB had to push the issue.
 

Mooseman

Moderator
Finished up the column and DIC install. All went well. DIC responds properly to the buttons and found out my two rear tires were low, hence the reason for the TPMS light. Elected to not swap the ignition key cylinder or sensor yet so did a VTD relearn using the Tech 2, so that eliminated the flashing security light. It will be annoying having a different key for the doors but I never use it. I may swap the cylinder at a later time. Will get a couple of spare keys made for this one.
 

Sparky

Moderator
Got minorly annoyed at the elusive pulley squeak but I'm not feeling like trying to chase it down. I'll call it character. Goes along well with the occasional cold start lifter tapping lol.
 

Mounce

Well-Known Member
Yesterday.. But.. Remounted my reverse led bars with some #14 self tappers hoping they'll fair better than the snap-tastic #10's. Also removed passenger side turn signal housing and drilled two drain holes in the bottom of the lens. Yes, after resealing them it still leaked and collected water driving back from Kentucky with about 5 hours of rain at 60-80 mph. I'm guessing it's leaking around the sockets or the vent hole on them. Luckily I got the drain holes installed before chrome damage occurred. Screw it, I'm okay with it. Driver side is still dry so I'll leave it alone until it acts up.

Oh and emptied all of my tools out of the tool box and back into the roll around.
 

djthumper

Administrator
Getting it ready for registration renewal.
 

TollKeeper

Well-Known Member
Still trying to get used to the lack of sound effects as I go over bumps. Weird.
Im not looking forward to getting used to NO bump steer after my rebuild.
 

gpking

Well-Known Member
The TrailBlazer celebrated its 17th birthday last month. (It needs another ignition switch soon).

I hit the pick-a-part for some goodies for the Silverado - connectors to splice in so I can hook up my 2nd gen towing mirrors, and an electrochromic mirror with temp and compass ($10)!
It's doing interior temp duty right now until I figure out where the hell the existing sensor wires go (it reads 0 degrees on the factory wiring, so I know there is no sensor on the other end).
Snapchat-1901810129-s.jpg

The wiring diagram makes it seem like the wires run all the way to the non-existent sensor location (hey, maybe the connector is there). I'm not looking forward to tracing these out so I'm probably just going to run my own wires once I realize disassembly of the front clip takes more than 5 minutes of effort.
1578875705751.png
 

Blckshdw

Moderator
It's probably right near the top of the grille, in front of the radiator.

I racked up some highway miles on mine. Drove it across town to help a buddy wrap up an incomplete alternator replacement on his XUV. We dropped one of the engine lift hook bolts down into the gap between the alternator and head, and I didn't have my magnet to get it out, so had to make a 2nd visit. When we fired the truck up to test the alternator, it idled shockingly rough. Sure some of that could be a dirty throttle body, but I suspected motor mounts as it's an 04 with upwards of 170K miles.

Brought my ramps this time, but we really didn't need them. Saw the telltale drips under the passenger side mount, along with some engine oil drips so it was easy to tell the difference. Since he's planning to get his valve cover and head gaskets replaced in the next month or so, he's gonna buy the motor mounts and have the shop swap those out too.
 

Mooseman

Moderator
The TrailBlazer celebrated its 17th birthday last month. (It needs another ignition switch soon).

I hit the pick-a-part for some goodies for the Silverado - connectors to splice in so I can hook up my 2nd gen towing mirrors, and an electrochromic mirror with temp and compass ($10)!
It's doing interior temp duty right now until I figure out where the hell the existing sensor wires go (it reads 0 degrees on the factory wiring, so I know there is no sensor on the other end).
View attachment 92625

The wiring diagram makes it seem like the wires run all the way to the non-existent sensor location (hey, maybe the connector is there). I'm not looking forward to tracing these out so I'm probably just going to run my own wires once I realize disassembly of the front clip takes more than 5 minutes of effort.
View attachment 92626
The wiring is there but only to the underhood connector near the fuse box. They terminate there with the corresponding wiring to the sensor on the other side of the connector is missing. You could just chop the two wires there and make your own wiring to the sensor or do like I did and take the two wires with its pins from the connector from a junker so it's like stock. We already have a couple of writeups on this for both methods:

How to: Add a Temp / Compass rear view mirror
How to: Add Compass and Temp rear View Mirror
 

$ Khalid ! 9130

Well-Known Member
Been a really busy few days. Ever since the Yukon broke down on the highway on Saturday I've been busy trying to get it sorted out. Had the fuel pump, EVAP cannister and solenoid replaced today, however a transmission issue has popped up where it's slipping between 2nd and 3rd at around 60 - 70 KMPH. Mechanic said it's a common issue with the 4L60 transmissions and would require the transmission be dropped to replace TCC sensor and Solenoid. Started a thread in the relevant section, would really appreciate some help on how to proceed further with it. Other than that the TB is now on double duty. Plan to get around to doing the reverse LEDs on it. Also needs new front link arms and is currently throwing a P0442 Small EVAP Leak which I need to look into as well, before I leave in about two weeks. And in the worst case scenario which of the newer models would be a recommended upgrade for the old man if we decide to get rid of the Denali. Looking for something that can match the driving comfort of my one with good reliability. Appreciate it!
 

Riktar

Active Member
I closed the back hatch after throwing out the garbage, got in the car and upon closing my drivers door heard a terrible noise.

My rear glass shattered into a thousand pieces.

And my comprehensive has a $500 deductible. 😡

I will chalk it up to "What did my Trailblazer do to me today?"

UGH....
 

Mooseman

Moderator
I closed the back hatch after throwing out the garbage, got in the car and upon closing my drivers door heard a terrible noise.

My rear glass shattered into a thousand pieces.

And my comprehensive has a $500 deductible. 😡

I will chalk it up to "What did my Trailblazer do to me today?"

UGH....
U-pull yard is your friend in this instance and may be the only choice as I have heard that these are not available new.
 

Riktar

Active Member
I will be searching for a used one today.
 

TollKeeper

Well-Known Member
GMT360 - Tried to start it for the first time in a couple weeks. Click, click, whirrrrr (headlight washers). Guess I need to take it and have the battery checked next time I get a moment to work on the cars.

GMT250 - Trying to track down this "dash reset" it keeps doing completely at random. Its like someone turned the key off to the truck for a split second, all the electronics reset, but the engine and transmission act completely fine. My wife had the idea it was the BlueFusion, but it was doing this before I installed that. I dont know what else to check really.
 

Mooseman

Moderator
Ignition switch
 

gpking

Well-Known Member
It's probably right near the top of the grille, in front of the radiator.
I hope so. The few wrecked examples I saw were missing any trace of it.

The wiring is there but only to the underhood connector near the fuse box.
Cool, I'll see if this is also applicable on the Silverado. I'm kicking myself for not ripping open the harness further to see where they went...
 

HARDTRAILZ

Moderator
Stretched its legs on the interstate to work again. Also looking at doing an open newer LT grill for a change. Always wanted to give one a whirl and just cut one of my other grills to fill the headlights. I had a grill saved at 440, but now can't find one under $60...
 

BrianF

Well-Known Member
Since it warmed up to a balmy -30C yesterday, I took the C1500 into town for some gas. She has been sitting for quite some time now. I plugged it in for a couple hours and she fired right up. After a few miles down the road, I smelled coolant but couldn't find a leak. Thinking with the cold and all it puked a bit up. Oh well, it ran fine but on the warmer side the whole time.

My Trailblazer fired up real nice yesterday after a few hours of being plugged in but today.... well that was another story. It was -37C ambient when I plugged it in this morning (2:30am) but the temp drops even more around 7am. So it was closer to -40 and the poor girl sure struggled. It did fire up after a few turns but the PS pump howled for several minutes and she made some pretty painful sounds. She drove fine after that.

I double checked my cord and it was power but I am wondering if my block heater plug's connection is poor. I had replaced it a few years ago after smashing it to pieces in a fit of rage in -40 weather. It shattered like glass. The new plug has some movement to it, so thinking the connections are crappy. The TB really felt like it was not plugged in and I never did hear the crackling sound of the block heater this morning.
 

Reprise

Lifetime VIP Supporter
Bought (another) new battery for the Envoy. Same issue -- lack of use sulfated the battery.
I had disconnected the terminals before doing the last work on it, and put the charger on the battery, as it was turning over slowly to begin with. Sure enough, the charger reported back that the battery was bad.

The last time, I was able to 'fool' the charger into recharging the battery. But since that resulted in a battery that juuuust baaaarely cranked after fully charging, I didn't feel like trying that again.

When I removed the 'cooling cover' apparatus, I saw the mfg date was 8/16 - so just past the 'full' 36mo warranty. I could've taken it back to Wally World for the pro rata warranty, but that would mean another one of the same batteries and fighting sulfation again. After buying 3 of them, and exchanging all three due to sulfation, I've had enough of (N)Ever Start 'Maxx', thank you.

Time to take a new approach, and since I'm not taking the Voy cross-country any longer, I don't have to worry about warranty exchanges in far away places (that was why I bought WM batteries in the past... one in every town.)

So... this time, I bought an AGM battery (if anyone's looking for one, like @Matt from a post a few weeks ago), I got mine from Batteries Plus - they have a 20% off code (CDP13175) good until end of February. They also have a $10 mail-in rebate good until Jan 31. Take those two together, and my net cost will be $164, exclusive of taxes). You have to purchase online, and pickup in-store, but that's not a problem for me.

The only place I found an AGM cheaper was Sam's Club (same battery; one year less on the warranty). I get 5yrs warranty on this one - 4 from the store / mfg, and an extra year, thanks to the credit card I used to pay for it (AMEX). For me, I'd have to buy a Sam's Club membership, so cost was a wash.

Why AGM?

The rate of self-discharge is very low, compared to a conventional lead-acid / 'flooded' battery. Generally, it's in the neighborhood of 1-2% per month (if not connected). This makes it a better choice for vehicles that don't get driven often (and that you don't / can't / won't disconnect the battery to put it on a float charger until next usage).

And before you ask... no, I don't have parasitic drain issues. I just tend to use one vehicle for an extended time, and the other one sits (most of the time, until I have to work on one or the other). Since they're parked outside most of the time, I don't drag them in the garage to put them on a float charger.

(on edit - this is probably the most important thing, and I forgot!)
AGM batteries can be deeply discharged without harming them - to as low as 20% of rated charge. With a traditional 'flooded' battery, anything below 50% SoC shortens their life. And we're talking about a narrow range, voltage-wise -- if 12.7 volts represents a 'full' charge, 12.10 is 50%, and by the time you get below 11.5 volts, the traditional battery is effectively 'dead' (even if you can somehow revive it, its life & output is drastically shortened by that point).


Another benefit that I found out about just now - they are practically immune to freezing (b/c they don't have as much electrolyte. Even if it should freeze, the battery won't be harmed (you just won't get any output until it thaws). So that's nice, for those of us who live in The North.

You do need a charger that can accommodate AGM batteries. Best way to charge them is like making BBQ -- low & slow. Topping mine off now, and then it'll go into the Voy. When I bought the last charger, I thought ahead and got one that could charge AGMs. Yay me... lol.

Since both the Envoy and the Sierra use the same Group 78, if I lose the Voy to rust over the next few years, I can always swap this 'investment' into the Sierra. So I'll get my use out of it.

Finally, this one is made in USA, if that's important to you. The info I have says it's made by East Penn -- which is probably the best (only?) remaining US manufacturer -- JCI makes most of theirs in Mexico now, from what I've seen)

Will report back if I run into any issues with the AGM. Fingers crossed (both for the battery and for the Envoy not to succumb to rust during the warranty period) 🤞 :yikes:
 
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BrianF

Well-Known Member
Well today was interesting..... rolled in to home around 230am. Flipping cold. Plug the Trailbalzer in, no crackle sound. Not good. Grab my headlamp and rip into the old block heater plug, poor connection. I clean it up and break the plug trying to tighten it back up. Hobble it together and plug it in.... kind of sounds like it's working. Well that's all I got.

Wife wakes me up at 8am, Trailblazer won't start. F sakes! I run out and I had to work the throttle but I just got it to fire on a cylinder and two at a time. Got it running. Barely.

I drive it around the yard to loosen her up and send the family on their way. No sleep for me as I then get called out for some garbage 2 hours away. Get called off 40 minutes later but hey, just got paid to drive my work vehicle to the neighboring town to have coffee with my buddies and buy a new plug.

Get home, plug my C1500 in for 30 minutes, which should be plenty at what looks like -35c right? Barely can turn over but fires. Let it warm up and roll to town to install the new plug. My old boss clears out the heated bay for me to roll in.

So I cracked out the multi meter. I got continuity and resistance on the wires after cutting the old end off. Patch on a newer more bulky plug. I plug it in and traced the wire to the block heater. Viola!!! Thing is getting flipping hot!! Success will be measured if the bitch starts tomorrow morning.

The old plug had way too much play on the cord and allowed the wires to fray. I taped up the wire a bit and the new plug clamps down way better.20200115_095708.jpg
 

TollKeeper

Well-Known Member
Tuesday night, got my GMT360 jump started, moved it closer to the garage, and put a 10a charge on it for 1 hour, and a 2a charge on it for 4 hours. Drove it to work on Wednesday, and home, only to realize my bluefusion adapter or my radio is completely fried. Keep getting this XM error on the screen. Parked it in its normal long term parking spot, made sure everything was unplugged this time. And went in for some dinner. Debating if I need to search for another bluefusion or 9-7x Nav radio again, or try to find a iSimple.

Drove the GMT250 to work today. I really wish this truck had heated seats. Its really nimble, peppy, and great to drive. I still prefer my GMT360. Need to work on getting a heated seat option on this 250.
 

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