What did you do to your GMT today? [Part II]

Zaab

Member
Apr 30, 2025
63
Ohio
IMG_3237.jpegIMG_3238.jpegTry changing transmission fluid and filter last night. Not good! For v8 it got a exhaust pipe and clamp preventing the pan get drop or go back on. I wrestled it last night with little progress, have to hammer in bit and bit and hope nothing is broken. Ughhh!
 
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Dec 8, 2021
42
Silver Spring, MD
I plan on replacing the thermostat, water temp sensor and right side CV diff gasket/seal this weekend, but I found it was cheaper to order an entire crow-foot ratchet box end set than getting a single one! RockAuto keeps getting my business for a reason.
 
Dec 8, 2021
42
Silver Spring, MD
View attachment 117416View attachment 117417Try changing transmission fluid and filter last night. Not good! For v8 it got a exhaust pipe and clamp preventing the pan get drop or go back on. I wrestled it last night with little progress, have to hammer in bit and bit and hope nothing is broken. Ughhh!
Just did this on my 4.2, but managed to knock the shift linkage around enough so it pop off two days later. Man, that is one annoying fix to have to limp home after throwing it into DRIVE while the SUV is running.:Banghead: Thanks Dorman for making good replacement parts here.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,654
Ottawa, ON
Try changing transmission fluid and filter last night. Not good! For v8 it got a exhaust pipe and clamp preventing the pan get drop or go back on. I wrestled it last night with little progress, have to hammer in bit and bit and hope nothing is broken. Ughhh!
It looks like the cross-pipe has already been cut and welded. I don't know why that clamp needs to be there? I remember doing it on my Saab, it was tight but doable.

Leave it to GM engineers to put a hot exhaust pipe right under the tranny pan to bake the fluid. :mad:
 
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Zaab

Member
Apr 30, 2025
63
Ohio
It looks like the cross-pipe has already been cut and welded. I don't know why that clamp needs to be there? I remember doing it on my Saab, it was tight but doable.

Leave it to GM engineers to put a hot exhaust pipe right under the tranny pan to bake the fluid. :mad:
Carfax show exhaust repair work done in 2021, I wonder this may not be oem config.
I have become the next guy they screwed up with didn't I? lol
 

Zaab

Member
Apr 30, 2025
63
Ohio
It looks like the cross-pipe has already been cut and welded. I don't know why that clamp needs to be there? I remember doing it on my Saab, it was tight but doable.

Leave it to GM engineers to put a hot exhaust pipe right under the tranny pan to bake the fluid. :mad:
Why they choose to skip drain plug for pennies is beyond me
 
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Zaab

Member
Apr 30, 2025
63
Ohio
It looks like the cross-pipe has already been cut and welded. I don't know why that clamp needs to be there? I remember doing it on my Saab, it was tight but doable.

Leave it to GM engineers to put a hot exhaust pipe right under the tranny pan to bake the fluid. :mad:
Update: I won
Blessed by Odin, my trusted hammer once again aids me during the most difficult time.:thankyou:
I was able to get the cover in, replenish fluid, start the car, run all the gears and feel the engagement. Just need a test drive to relearn.

ps: I find the breath hose for my rear diff with seized fill plug. Have anyone tried filling the diff by taking off the hose and add from breath port? If my cover is seized as well, I plan to add maybe half a quart and call it a day, see if there is any improvement. Right now it has a wine noise on highway.

pps: Would like to emphasis the importance of PPE. Please Wear It! From safety goggles, gloves, face masks, protective cloth to redundant vehicle lift protection. I was lazy and didn't use my goggles last night, and a splash of used transmission oil almost get into my eye. Luckily I wear regular glasses so get spared from a trip to ER. Shortcut PPE does not worth it.
 
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Mooseman

Original poster
Moderator
Dec 4, 2011
26,654
Ottawa, ON
: I find the breath hose for my rear diff with seized fill plug. Have anyone tried filling the diff by taking off the hose and add from breath port?
Yes and apparently it's painfully slow because the hole is so small.
 

Zaab

Member
Apr 30, 2025
63
Ohio
Yes and apparently it's painfully slow because the hole is so small.
I got it. I bought one bag of valvoline gear oil and two quart bottles as refill. Just squeeze the bag and I can hear the sound of fluid dropping into pan.
No oil change for my diff since 2009. oil is glidder and the steel pan is jet black, full of clutch material. Truck drive better afterwards. First time overhaul a vehicle and I'm proud of the progress.
 

Zaab

Member
Apr 30, 2025
63
Ohio
I got it. I bought one bag of valvoline gear oil and two quart bottles as refill. Just squeeze the bag and I can hear the sound of fluid dropping into pan.
No oil change for my diff since 2009. oil is glidder and the steel pan is jet black, full of clutch material. Truck drive better afterwards. First time overhaul a vehicle and I'm proud of the progress.
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The fresh oil is when I am experimenting with adding fluid from vent hole. It's jet black inside with sparkles and clutch material all over the place. It is a tough diff! I will taking proper care of in the rest of its life span.

With that said, this is the final chapter for my first stage restoration. No more work for a while!

PS: I cross thread one bolt. Will a new bolt fix it, or I need to put down new thread in the hole?
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,654
Ottawa, ON
Might have to chase the thread first with a tap. Maybe only the bolt threads got boogered up so look at the threads and try a new one first.
 
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flyboy2610

Member
Aug 24, 2021
614
Lincoln, Ne.
My 2005 Yukon 5.3 has an exhaust crossover that just barely prevents removal of the pan also. I just needed a smidge more. So I ran a 2x4 across and used some blocks to the frame rails and then a ratchet strap to pull that pipe down just a tad.

View attachment 117433
The handyman's REAL secret weapon: ratchet straps!
They also work good for getting the rear axle moved back over when you unbolt the shocks and track bar for a spring replacement! :wink:
 

Zaab

Member
Apr 30, 2025
63
Ohio
The handyman's REAL secret weapon: ratchet straps!
They also work good for getting the rear axle moved back over when you unbolt the shocks and track bar for a spring replacement! :wink:
... we, uh, will be spared from this when just replacing the shock, won't we?
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,654
Ottawa, ON
After a 1200 km trip towing the RV trailer, I did an oil change on the Sierra at 33% OLM and about 8k km. Taking a hint from GM with their 6.2 debacle, I put in Castrol 0w30 European formula for gas/diesel engines. I no longer felt comfortable running the watery 0w20 GM specifies during summer months and towing. If increasing viscosity to 0w40 in their exploding 6.2 is good to help prevent damage, then it should be good in my little diesel. I might lose 0.1MPG though :laugh:

I was thinking of going to Rotella T6 0w40 but figured it was too much of a jump in viscosity and is an older formulation. Did see a couple of guys online that switched to 0w30 with great results. I do have a stockpile of ACDelco 0w20 that I will use during winter months and switch to 0w30 for the summer towing season.

I did see that 2019 and 2020 saw issues with chain stretch on the 3.0L diesel and my 2021 has the updated timing chain so I dodged that bullet. Still debating replacing the valve body in my 10 speed tranny to a modified one for over $1000USD. GM do have an extended warranty on the issue however are just using their own parts that still have the same defects. I'll continue doing my 50k km tranny fluid and filter changes. I'm at 88k km now.
 

Zaab

Member
Apr 30, 2025
63
Ohio
After a 1200 km trip towing the RV trailer, I did an oil change on the Sierra at 33% OLM and about 8k km. Taking a hint from GM with their 6.2 debacle, I put in Castrol 0w30 European formula for gas/diesel engines. I no longer felt comfortable running the watery 0w20 GM specifies during summer months and towing. If increasing viscosity to 0w40 in their exploding 6.2 is good to help prevent damage, then it should be good in my little diesel. I might lose 0.1MPG though :laugh:

I was thinking of going to Rotella T6 0w40 but figured it was too much of a jump in viscosity and is an older formulation. Did see a couple of guys online that switched to 0w30 with great results. I do have a stockpile of ACDelco 0w20 that I will use during winter months and switch to 0w30 for the summer towing season.

I did see that 2019 and 2020 saw issues with chain stretch on the 3.0L diesel and my 2021 has the updated timing chain so I dodged that bullet. Still debating replacing the valve body in my 10 speed tranny to a modified one for over $1000USD. GM do have an extended warranty on the issue however are just using their own parts that still have the same defects. I'll continue doing my 50k km tranny fluid and filter changes. I'm at 88k km now.
Which brand of 0w-40 you using Mooseman? And Euro spec oil cause no problem for us GM vehicle?
 

Zaab

Member
Apr 30, 2025
63
Ohio
IMG_3304.jpeg
IMG_3311.jpeg
Styling upgrade for the radio antenna and change the rear lower control arm. I can feel the performance improvement, rear end is much tighter now.

Have a lot of fun trying to align the control arms. Eventually I used brake compression tool on one end and push the bolt as hard as I can while running impact drive to align the holes and push in. Not sure why it’s so hard on one side but not the other!
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,654
Ottawa, ON
Which brand of 0w-40 you using Mooseman? And Euro spec oil cause no problem for us GM vehicle?
I used 0w30 Castrol Euro gas/diesel formula in my '21 Sierra with the 3.0L diesel. It's not a huge jump in viscosity and the zinc content is good for diesels. The only time zinc can be an issue is for vehicles with cats. Higher viscosity can be an issue with variable cams however the 3.0L does have a 0w30 version of oil for areas with higher temps.
 

azswiss

Member
May 23, 2021
1,070
Tempe, AZ
Replaced the battery. After a marginal start last night I had it on the charger for 12 hours only to have it peak out at 12.4V and another marginal start. Got 3+ years out of this last one so no complaints (they really don't like the heat; typical life here in the desert is ~24 months). AAA Roadside came to the house and swapped in the new one all in for less than sticker price at AutoZone.
 

Mooseman

Original poster
Moderator
Dec 4, 2011
26,654
Ottawa, ON
The front bumper plastic corner bracket had broken off and the bumper was flopping around. While taking off the two top bolts, they broke. Once I got it off, I then saw the bracket was completely gone and the bumper looked like it got hit with a scrape and a crack in it.

Ran to Kenny-u-Pull to get another one and also picked up a rubber cup holder liner that was missing in mine. While there, I saw an '06 that was horribly modified with a front rack that was booger welded to the front frame and a winch as well as e-fans. I guess the owner drank that Koolaid.

PXL_20250715_185700753_resized9158963314274562180.jpgPXL_20250715_185707578_resized3537331546992289831.jpg

Used some 5 minute epoxy to glue the bracket onto my bumper and added some to the other bracket that was still there. While that was hardening, I decided to install the front tow hooks I had been hoarding ever since I scrapped my '02 EXT. Just cleaned the rust off a bit and painted them with some semi-gloss black rust paint.

PXL_20250715_203541724_resized329980087960087262.jpg

For those two broken top bolts, while trying to center punch, I punched out the the weld-nut from the frame. Decided to punch out the other one and use plastic push retainers instead of bolts, which one was already in use in the middle. The bumper went back on no problem.

Then went to reinstall the grill and the right side "wing" broke off. This was the original grill from my '02 which I had Plasti-dipped black. I still have the original chrome one, I just have to find it and Plasti-dip it too. Most of the metal clips are also in bad shape.

Didn't get a lot of pictures as it was a 4H day (Hot, Humid, Hazy and Hot) and didn't think of that too much. If I can find the grill, I'll post an update.
 

Mike534x

Member
Apr 9, 2012
1,034
Did a tune up on the Envoy (noticed MPG was dropping, and she felt a bit sluggish), driver side plugs were oil fouled. Seems like I may need to consider replacing the driver side valve steam seals to see if that helps. Plugs had about 50k on them since I changed it last, passenger side looked excellent with regular wear. However, shortly after the tune-up she developed a low-idle miss......and it can definitely be felt. Took about a week before she threw the CEL for #2 (P0302). Since the misfire timing coincides with the spark plug change, I must've damaged the plug from dropping it on the frame, or I screwed up the iridium tip/gap. I had completely blocked out of my mind, how much it sucks trying to get at #2. Ordered another plug, and set of wires to play it safe in the off chance I mangled either trying to re-install them.

I also need to crawl under, and pull the inspection cover on the bellhousing to see if the Rear Main is my confirmed leak. The spot in my garage and drive way has grown considerably over the last few months, so I'm beginning to wonder if the rear oil pan seal is the main culprit or the VLOM is leaking at the rear of the block and I just can't see it.
 

Mike534x

Member
Apr 9, 2012
1,034
It looks like the cross-pipe has already been cut and welded. I don't know why that clamp needs to be there? I remember doing it on my Saab, it was tight but doable.

Leave it to GM engineers to put a hot exhaust pipe right under the tranny pan to bake the fluid. :mad:

Definitely a poor repair job, maybe my eyes are deceiving me....but I circled this part of their picture. The pipe leading off the cat looks like its was pounded in (circled it) for it to make that curve. Maybe its the lighting but that whole inside facing portion looks "flat" going into the bend.

I'm wondering if that was yanked off a regular GMT-800 and hacked to fit under there, something is way off with that setup....even for aftermarket.
 

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Zaab

Member
Apr 30, 2025
63
Ohio
Definitely a poor repair job, maybe my eyes are deceiving me....but I circled this part of their picture. The pipe leading off the cat looks like its was pounded in (circled it) for it to make that curve. Maybe its the lighting but that whole inside facing portion looks "flat" going into the bend.

I'm wondering if that was yanked off a regular GMT-800 and hacked to fit under there, something is way off with that setup....even for aftermarket.
Took me a while to realize it is MY Saab lol. Yuck I hope it's not the case, although very likely. A muffler shop did work in 2021 but carfax report didn't show shop name...
I got new control arm bushing arrived, so when I work on that I will double check. Thanks!
 
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Zaab

Member
Apr 30, 2025
63
Ohio
Did a tune up on the Envoy (noticed MPG was dropping, and she felt a bit sluggish), driver side plugs were oil fouled. Seems like I may need to consider replacing the driver side valve steam seals to see if that helps. Plugs had about 50k on them since I changed it last, passenger side looked excellent with regular wear. However, shortly after the tune-up she developed a low-idle miss......and it can definitely be felt. Took about a week before she threw the CEL for #2 (P0302). Since the misfire timing coincides with the spark plug change, I must've damaged the plug from dropping it on the frame, or I screwed up the iridium tip/gap. I had completely blocked out of my mind, how much it sucks trying to get at #2. Ordered another plug, and set of wires to play it safe in the off chance I mangled either trying to re-install them.

I also need to crawl under, and pull the inspection cover on the bellhousing to see if the Rear Main is my confirmed leak. The spot in my garage and drive way has grown considerably over the last few months, so I'm beginning to wonder if the rear oil pan seal is the main culprit or the VLOM is leaking at the rear of the block and I just can't see it.
Dang I guess #2 is on passenger side? What a headache
 

Mike534x

Member
Apr 9, 2012
1,034
Dang I guess #2 is on passenger side? What a headache
Yeeeep. Accessible through the wheel well while the strut is removed, or you remove the washer fluid reservoir/pull it out of the way to get access from the top. Top side isn't bad if you got small enough hands, otherwise I found a 5/8 spark plug socket with a hexagonal head to wrench it in/out to work well enough but its still a bear. Even worse when trying to seat the plug boot onto. :hopeless:

As much as I love the V8....I absolutely hate how cramped it is under the hood.
 
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