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No idea if this has been posted before but I haven’t been able to find anything like this. Then again maybe I didn’t try hard enough? I decided to install a drain plug in my pan and thought I would make a quick guide on the subject if anyones interested.

Anyways, below is a guide on changing your tranny filter which inadvertently changes some your trans juice. Although, in reality, your only changing like 30% of the total fluid. But at least you can see how to do it before you decide to get your hands dirty.

I went to the parts store and they listed two different tranny pan styles and filter kits for the 6 cylinder model TB’s in ’03. There is a deep pan that is more rectangular and there is a shallow pan that is squarer. Mine uses the shallow pan. Parts stores, like Advance Auto and Autozone should have a picture listed on their computers. I also used Dexron VI, Supertech brand from Wally World. Never had any problems with any of the transmission fluids that Warren Distribution makes for the Supertech brand name.

Basically you’ll need 5 qts of fluid like Dexron VI, a tranny filter kit, a torque wrench, a ½” socket with like 3” extension, jack and stands, and some clean paper towels.


I’m not too familiar with the TB but one thing I know for sure is… dang that thing is low. Might be easier to work on if you jack it up and pop in some jack stands. I have no idea where the jack points are on these trucks so I’d suggest checking the owner’s manual before getting any ideas from this picture.


Look for the tranny pan in the middle of the vehicle. Big silver looking square/rectangle thing. Use a ½” (I think?) socket with extension and unscrew the bolts on one side of the pan. There where 16 on the pan I took off. They are all under very low torque so they should be fairly easy to undo.



Like I said, unscrew one side of the pan first then work your way around, this way the fluid will leak out of one side first and you can catch the fluid with a pan easily. Leave two bolts in and then knock the pan to coerce more of the fluid to spill out over the side. Basically, the less fluid in when lowering it the less chance of spilling ATF all over your new driveway.


Should see something along the lines of this.


The magnet will have metal fuzz over it. Shouldn’t be seeing any big chunks, if you do then you may have future problems a brewing. This particular vehicle had 45K on the clock with four summers worth of once a week towing a 18ft boat. No big flakes of metal, just some minor fuzz, everything seems A’ok.


Believe it or not some people actually forget to remove the old gasket material. Use a razor blade gently to get it off if it doesn’t come off by hand. Check under the vehicle also for any material.


Skip this step if you don’t plan on installing a universal drain plug into your transmission pan. All of our larger vehicles now have these since they all tow in the summer. When 40k rolls around we simply open up the universal plug, draining the pan and pour in fresh fluid. Also makes it a cleaner job to drop the pan if you need to drop it again in the future. If you do install one then make sure the nut that sits inside the pan does not come into contact with anything when the pan is bolted back onto the tranny. This particular drain plug kit required a ½” hole to be drilled and then the two nuts to be tightened down. I change my filters every 100K after installing drain plugs.


Clean up the pan with some sort of solvent cleaner and lay down the new gasket that came with the filter. A one piece gasket is great because it will hold all 16 bolts in place for you while you hold the pan up against the tranny with one hand. Alternatively you can use gasket maker from a tube but I find that it is just hard to remove when dropping the pan next time and there is a chance that the pan can shift (ruining the bead of gasket maker) while trying to thread in the bolts.


The tranny filter is either a big black looking thing or a big silver looking thing that has a tube type extension that connects to the transmission. It is not held down by any bolts. Just grasp firmly and pull it out, try not to rock it back and forth to much otherwise you will have to replace the friction o-ring that holds the filter tube thing in place. A filter kit will come with a new o-ring deal but you will need to use a gasket removal tool to get it out (I think?) you could possibly use a small flathead but be careful. I pressed the new filter in and it made a good seal so I didn’t bother to replace the ring.


Position the pan back in place and hand thread in all 16 bolts. Make sure that none of them are cross threading! Otherwise you’re in some trouble. If you installed a universal drain plug in your pan then check to make sure its in the closed position. No idea what torque values are required for the TB but my Jeep calls for a value of 12ft-lbs for the bolts on the tranny pan. I did the same for the TB, if I where you then I’d go check what values are needed.


Pour in some new fluid, I used Dexron VI. You should notice no major change in shifting performance or feel. If you do then that means you either waited way to long to change the fluid and need to flush out the entire system or crack open the drain plug you installed and drain and fill again. Or you used the wrong fluid.

Then you can:

Take it for a drive to fully warm up fluid and check the level with engine idling.

Crack open a cold one to celebrate a job well done.

Recycle trans juice at local parts store.
 

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2003 chevy trailblazer_ls
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Very nice post. I have a question, where did you get the drain plug kit? Nice idea while the pan is off. I do need to replace my pan, it kinda has a "little" dent in it. I got really lucky in the desert and did not punch a hole. :D
 

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Nice quick writeup, and the first post to boot! :thumbsup:

As for the trans pan bolts, I think the GM manual calls for like 10-12 ft/lbs (basically snug plus a little). And for jacking points, that looks right but look at the manual first everyone!
 

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I know not many have access to a mig welder but I tack welded a 1/2" nut in the pan and use short 1/2" bolt and copper sealing washer. The grooves in the nut let fluid drain from the bottom.
Not to say you will, but I had a problem with one of those drain kits loosening.

 

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From the pic it appears there are no interference issues when changing to a deep pan if you have a shallow one, am I correct???

I ended up buying a 3 5/8" deep pan with a drain in it and I'm hoping to change it over next week...
 

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I know not many have access to a mig welder but I tack welded a 1/2" nut in the pan and use short 1/2" bolt and copper sealing washer. The grooves in the nut let fluid drain from the bottom.
Not to say you will, but I had a problem with one of those drain kits loosening.

I had the same problem on a different vehicle... Luckily with the kit I had you could retighten from the outside of the pan and didn't have to drop the pan to do it...

One nice thing about a drain plug is that it makes tranny maintenance much easier and more likely to be done by us DIY'ers... I used to change the pan fluid every time I did the oil the first 3-4 times then every other time after that...
 

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Well, I managed to do the filter service today... I already had a deep stock pan on my transmission, but I got an even deeper pan from eBay some time back... I picked up the new pan mostly for the drain plug already built in, but the extra capacity doesn't hurt either... One nice thing about the frame on our trucks is that you can fit a really deep pan on there without worrying about interferrence issues... The replacement pan seems to be about 1" deeper than the stock deep pan and still sits about 1" above the bottom of the frame...

I'll probably drain the pan again this weekend just to get more of the old trans fluid out and changed... I was amazed though, the new pan and trans cooler (new also) required about 8 qts of fluid in all to get her topped off to the hot/full mark after some freeway driving to get the trans hot... Now after another drain I should get a good feel of the new fluid change amount required...

Next is a gauge pod so I can install my Aeroforce gauge and hopefully my new PCM will arrive so I can install the tune as well...
 

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The replacement pan seems to be about 1" deeper than the stock deep pan and still sits about 1" above the bottom of the frame.....
I recall there's two filters available, one for shallow pan, one for deep. I have the deep pan and the filter rested on the bottom of the pan. Do you have any concern with the deeper pan and how the filter might react if not touching the bottom? Just a thought.
 

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I recall there's two filters available, one for shallow pan, one for deep. I have the deep pan and the filter rested on the bottom of the pan. Do you have any concern with the deeper pan and how the filter might react if not touching the bottom? Just a thought.
If the filter pickup isn't low enough, there is a chance that while driving, the fluid level will be too low on fluid and starve the pump. Installing a pickup tube and filter the right length for the deep pan might (?) fix that problem. If it were me, I'd check w/ a GM Tech at the dealer to see if this is OK to do.
 

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I recall there's two filters available, one for shallow pan, one for deep. I have the deep pan and the filter rested on the bottom of the pan. Do you have any concern with the deeper pan and how the filter might react if not touching the bottom? Just a thought.
I would think that would only be a concern if you were afraid of the filter slipping out of it's compression seal... The filter snaps in confidently and I've never dropped a tranny pan where the filter fell off without my help so I'm not too worried about that happenning now...
 

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If the filter pickup isn't low enough, there is a chance that while driving, the fluid level will be too low on fluid and starve the pump. Installing a pickup tube and filter might (?) fix that problem. If it were me, I'd check w/ a GM Tech at the dealer to see if this is OK to do.
It's a deeper pan but the fluid level in relation to the filter didn't change... The filter is still submerged to the same level it was with the original pan, there's just more fluid/space underneath it now... The dipstick still reads the level in the new pan the same way it did with the stock pan since it's reading fluid level from the top instead of the bottom...

I was curious about the differences in the shallow/deep pan kits but couldn't answer my question since the packages were all sealed, but I was wondering if the shallow pan filter kit was actually longer than the deep pan kit... The reason being is that the valvebody and filter stick down pretty far into the pan on my deep pan tranny... I'm wondering if the shallow pan kit might have a longer necked filter and maybe the valvebody sits up higher??? Other than the valvebody depth, I'm not sure what the difference would be between the kits unless maybe the shallow pan kit has a different filter shap alltogether and maybe sits up even closer to the valvebody???

I always thought our trannys were all the same since they are 4L60E series, but anyone know if there's a difference between a 2wd and 4wd transmission??? I'm wondering if the deep pans were installed on 4wd and shallow on the 2wd... The dealer used my VIN number to determine which filter kit I required and that I was 4wd...
 

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I would think that would only be a concern if you were afraid of the filter slipping out of it's compression seal... The filter snaps in confidently and I've never dropped a tranny pan where the filter fell off without my help so I'm not too worried about that happenning now...
Don't disagree. Everyone I've changed had to pull the filter out of the seal but it had been resting on the bottom of the pan. I was only bringing up the possiblility. If the filter is hanging without support, it has mass, over time vibration could move it out of the seal. Also fluid temperature variations, that cause materials to expand and contract could cause movement.
I only mentioned it 'cause there are 2 separate filters for the shallow and deep pan. If deepth isn't an issue seems like you could use the shallow filter on the deep pan.
 

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I only mentioned it 'cause there are 2 separate filters for the shallow and deep pan. If deepth isn't an issue seems like you could use the shallow filter on the deep pan.
The only thing I can think of is that the valvebody must somehow be different between the shallow and deep pan transmissions (2wd vs 4wd maybe???)... On my deep pan the filter hugged the bottom of the valvebody which sticks down past the pan mount pretty far... It doesn't look to me like a shallow pan would fit on my transmission...
 

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Very nice instructions for the ones who want to do this job for the first time. In my years I've learned to add Permatex to both sides of the gasket and a dab on the bolts. But that's just me and I never have bolts vibrating loose and never a leak from the pan. The other thing I'd like to add is, we're dealing with an aluminum transmission case. So,, don't go crazy tightening up the bolts. The best way is put your socket on the end of a screw driver type tool. Then you can't strip the aluminum threads, tighten them with all your might and you're not going to strip them. The Permatex will keep things tight and leak free. So, I just wanted to add a couple more ideas to a great step by step procedure.
 

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Q: tran fluid and filter change...what of torque converter

these instructions are good, but i suppose the only way to replace the other 40-60% of the transmission fluid, that is resting in the torque converter, is to get a flush ?

i am wondering if there is a way for the DIY to replace the torque converter trans fluid without inducing heavy pressure.

Q1: i've heard that flushes mix up particles backwards through the system and can cause flow problems ?

Q2: is there is a good "light" air pressure method into the trans fluid tube when the pan is off ?

is there any advise on this ? it will be my first trans fluid/filter change on my 2003 TB EXT at 85k. (after i change a CV, 2 dried out cracked booted upper knuckles, OEM struts and shocks. first timer there too.)
 

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Given the nice write up and pics posted, I believe this is a driveway project for me for one of the upcoming weekends. Nothing like the self satisfaction of being able to do a job yourself and knowing that it was done properly... not to mention much cheaper to boot.. :)

I'm pushing just over 78k miles right now. Should I take it in for the first time to have a flush done at the dealer or should I just drain/refill as noted in this thread?

One of these days, I need to get around to swapping out the shocks/struts as well...
 
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