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2005 gmc envoy_sle_xl
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Discussion Starter #1
I would like to drain the fluid on my 2007 TB as it already has 50,000 miles on it and it has been abused towing during the summer. Is there any reason why I can't just drill a hole in the pan and drain the fluid and then put in a stopper plug or bolt?
 

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2005 chevy trailblazer_ls
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607 Posts
Take a look in the articles section at the top of the site. There is one on flushing the fluid and replacing the filter. I would guess that when you have the pan down you could put in a drain. With my luck, leaving the pan on and drilling it, I would run the bit right through something important!
 

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2007 chevy trailblazer_ss_1ss
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Do not drill a hole in your transmission pan... that is not a good idea at all. If you're going to do this yourself, go buy a good quality filter kit (read: AC/Delco NOT Fram) and 5 qts. of Dexron VI. Get a big catch pan and take out all the 13mm bolts on the pan but one and then loosen that last one and let the fluid drain into the catch pan. Then remove the pan and check for any critters in there, if none are there then clean out the pan with some brake clean (don't use the kind that leaves a greasy residue, not good for a transmission) and reinstall. I can't remember if these trucks have a reusable gasket, but I don't think they do so you'll need to clean off the old one and use the new one from the kit. Then fill the trans with 4 qts. of fluid and go for a drive and then check the level and add the additional quart as necessary.

Honestly though, it is worth every penny to go to the dealer and get that done. It only costs $130 if I'm not mistaken and that alone is worth not getting covered in transmission fluid. Plus that includes the cost of parts you'd have to buy otherwise.
 

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2003 chevy trailblazer_ls
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1,708 Posts
I put on a Hughes +2 qt. finned trans pan with drain plug. Helps keep things cooler. Also makes draining much easier. Pan was $162.00. There are add on drain plugs for the stock pan and they run $15 or so. You install AFTER removing the pan and cleaning it.
 

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2005 gmc envoy_sle_xl
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Discussion Starter #5
Ok great guys. Thanks for the tips. Looks like I will be removing the pan and replacing the filter. Just one more question.I have an older 2002 Sonoma filter and gasket kit for the 4l60e. Since the TB uses a 4l60e can I just use this kit?

Thanks.
 

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2005 gmc envoy_sle_xl
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Discussion Starter #6
Also is the synthetic trans fluid you find at Walmart any good or should I go with a branded Mobile 1 or other branded dexron 3?
 

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2007 chevy trailblazer_ss_1ss
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I would go with a name brand. Just so you know though, Mobil Synthetic ATF and Royal Purple MaxATF are not Dexron VI compatible (though Mobil does have a Dexron VI fluid which is synthetic blend). I run Amsoil in my transmission, which is Dexron VI approved. Just go to the dealer with your VIN and buy a new kit so you know it fits. I'm not sure how many years it went, but some of these trucks had shallow and deep pans available.
 

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2006 gmc envoy_denali
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I too will be removing and replacing the transmission fluid in my 06 5.3L Denali. I have heard a lot of good things about Amsoil Synthetic trans fluid and will use that. I will also refill the entire transmission as per the instructions on this web site and add an transmission cooler. I have had a transmission cooler in every vehicle that I have owned since 1976 and never a transmission failure (I also put a 5000 lb boat in the summer). I have read a lot about whether to replace the seal in the tranny housing and what I think I'm hearing is if it doesn't come out with the filter then just leave it in and forgo the headaches associated with removing it. In addition I would like to add a drain plug to the pan and have found several from a couple of bucks to around $15.00. What I would like to know is where to I place it in the pan. I have read of some people putting it in the side at the back or the bottom at the back (assuming the front end is lifted if you are draining the oil). I want to make sure there are clearances for the inside of the plug
 

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2007 chevy trailblazer_ss_1ss
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You're talking about the seal for the filter right? If that sucker doesn't come out, it gets reused.
 

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2007 chevy trailblazer_ls
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I might be mistaken but I believe that on one side near a corner is a flat place to put a drain plug. Looks like the factory made it to put in a oem drain. Some older pans had drain plugs. If you can't find this place go with the instructions provided with the drain plug kit Hope this helps Jay
 

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2002 chevy trailblazer_ltz
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My only gripe with drain plugs is that they tend to leak after a few uses. The plastic washers/bushings seem to break down over time, and if you don't remember when you are at the parts store, you are SOL until the next time you drop the pan (1 inside, 1 out).
 

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2006 gmc envoy_denali
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861 Posts
I too am concerned about the drain plug leaking. Is the pan steel or some other kind of metal perhaps aluminum. If it is steel perhaps it would be good to have the bung welded in, this could also be done if it is aluminum, I think. If it is some other weird type of metal this may not be advisable. Any help this forum can give would be appreciated. In addition does anyone know what size the transmission lines are? I believe they are 3/8 or 5/16 inches. When I put the tranny cooler in I want to put brass connectors on the tubes and hose fittings on the rubber cooler hoses rather than just push the hose over the cut ends and hose clamp it to death.
 

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2007 chevy trailblazer_ss_1ss
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If you're worried about it leaking, then just don't do it... How often are you going to be dropping the pan anyway?
 

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2002 chevy trailblazer_ltz
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Welding would be advisable- the pan is steel.

I plan on dremeling the hole with the next one I install to see if it makes a difference. Smoothing the ridges on both sides of the pan may help.

Either way, say you are running 30k intervals on the filter. You could just drain every 5, 10, or 15k. I'd still continue to change the filter just as regularly as you had been previously.

I'm about 90% positive it's 3/8. I don't believe GM has used 5/16 tranny cooler lines since the 700R4 days. Our 96 Blazer and 05 Collie both have 3/8 lines, where our 86 Z28 has 5/16 lines, as well as threaded fittings versus the quick connect.

Here's a link to the install I did on the Collie. I believe the part number for the Hayden quick connect fitting was #397.

http://www.coloradofans.com/forums/viewtopic.php?f=8&t=61436

I've installed several coolers using the above fitting, and a variety of coolers. I strongly recommend using NEW hose clamps- I've had some bad luck with 'used' (leftover clamps from projects) not sealing correctly, or gouging the hose and causing a need to replace the entire line from the cooler the fitting. You'll need 4 clamps, total.
 

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2006 gmc envoy_denali
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Being a firm believer in maintenance rather than repair, I plan to change the filter about every 30-40K miles or so. The last Jimmy I had went 156 K miles with about 4 filter changes. I also have a 76 GMC Van with 500 K miles and the original transmission (but it is getting a little loose). If the pan comes out easy I will change the tranny filter every couple of years, maybe a little longer if it is a pain. The cooler just helps keep every thing together. Brazing the bung into the steel pan seems like the way to go, thanks for the info.
 

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2004 gmc envoy_sle
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117 Posts
RE:

You could do a transmission flush. I paid the dealer $230 + tax for my flush. I was at 72,000 Miles, it wasn't used for towing by first owner.
The fluid took a few hundred miles before it helped the transmission and felt brand new.
I wouldn't tow for at least 500 miles after a flush.

Use caution with the flush. I will not be doing another at 150,000.
Sean
 
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