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2002 chevy trailblazer_lt
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Discussion Starter #1
The front differential fill plug on my 2002 Trailblazer is stuck. This is the oversize plug. I used a 24" breaker bar with lots of force but it does not budge. I'm afraid any more force with shear the threaded shank of the plug. Does anyone have any suggestions on how to remove it?
 

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2002 olds bravada
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82 Posts
I had a similar problem on my last Bravada. I tried to use an impact gun and all I did was round off the head of the filler plug. I then used a torch to heat up the case and the bolt came right out. I need to change my differential fluid in a couple of weeks and you can guarantee that I will use a torch to loosen the plug.

Oh, I forgot to mention, I tried to use a breaker bar with no luck before I even tried the impact gun which is why I went for the impact. Don't use an impact, just put a torch on the case. I had to buy a new filler plug because of the impact.
 

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2003 gmc envoy_slt
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7,190 Posts
Wrap the threads with Teflon tape before you reinstall the plug.

It makes it a lot easier to remove next time. :m2:
 

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2003 chevy trailblazer_ltz
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125 Posts
I couldn't get mine out either last year. I used my cheapo Craftsman impact wrench, put in on medium ppower and let it work for a few seconds and it came right out. Put some anti-seaze on the threads and it came out easily this year when I checked the oil. I believe there is a rubber O ring onthe plug, so be careful if you heat it!
 

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2002 gmc envoy_slt
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539 Posts
A good 18mm, 6 point socket, a universal swivel and an impact wrench will get it out. You have to come through the wheel well to get a good angle. HTH c good
 

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2002 chevy trailblazer_lt_ext
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249 Posts
I used a short 18mm 6pt. on a good swivel head ratchet from below. Mine was pretty seized as well....
 

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2005 chevy trailblazer_ls
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346 Posts
I'm having the same problem with my 2005 TB. I have a bit of a diff leak so I'm Leary about using a torch. How flammable is diff. fluid?
 

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2002 gmc envoy_slt
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539 Posts
It's not overly flammable, but I would pay attention to not overheat the area. It is right next to the out put shaft seal. If you have to use heat, I'd use a good heat gun. Not recommended but If you have to use a torch, then spray the area down with a good water based degreaser first then wipe dry. Make sure you don't have ANY other fuel leaks or fumes present. And keep a fire extinguisher near by.

I bought a cheapo electric impact driver for $64.00. It's the BEST investment I've made in tools in a long time. Zipped that plug right out!

Keep us posted. c good
 

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2005 chevy trailblazer_ls
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346 Posts
It's not overly flammable, but I would pay attention to not overheat the area. It is right next to the out put shaft seal. If you have to use heat, I'd use a good heat gun. Not recommended but If you have to use a torch, then spray the area down with a good water based degreaser first then wipe dry. Make sure you don't have ANY other fuel leaks or fumes present. And keep a fire extinguisher near by.

I bought a cheapo electric impact driver for $64.00. It's the BEST investment I've made in tools in a long time. Zipped that plug right out!

Keep us posted. c good
Thanks so much for the answer. I'm going to clean the area good first. Good point on the seal. I have a 135lb air comp but I'll have to go get my big compressor from my ex's house and see if that does it with the heat.
 

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2005 chevy trailblazer_ls
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346 Posts
At mechanic. Three guys, 3 feet of breaker bar, no joy... Anybody know of a drain plug replacement that is a one way valve that you can fill through?
 

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2003 chevy trailblazer_ltz
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125 Posts
Impact wrench brought the plug right out on my 03. Put some antiseaze on the threads and it came right out a year later to check the oil level.
 

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2005 chevy trailblazer_ls
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346 Posts
Impact gun, PB Blaster and map torch weilded no joy for me. They tried an impact as well with no luck. The only thing I can think is it was cross threaded at my other mechanic.
 

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2002 gmc envoy_slt
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539 Posts
Oh man. That's a nightmare. You could get some kind pump with a tapered rubber tip and fill from the drain plug. Be aware that I was only able to get a smidge over 1 quart in my front differential before it spilled out of the fill plug. Be careful not to overfill. c good
 

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2005 chevy trailblazer_ls
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346 Posts
Ok, so I have accepted my fate and come to the realization that the front diff fill plug is in for good. So I decided to attack the root of the problem. Last year I posted how my mechanic tried to pry my ds axle off to replace the seal with no joy. Roadie pointed out how this is a low success method and banging it out is the way to go. Sometimes I make the mistake of thinking, if the mechanic can't do it why should I be able to?
Well decided to get my confidence up and went to lowes for some rebar. About an hour of pounding (Id say only one out of every 10 whacks were effective ones) and after separating the tripot joint, out came the axle. The seal came out with relative ease and new one in carefully with a dowel and rubber mallet. With the help of my trusty manual (that's for you roadie) and my conversion tool, I find the 2005 Trailblazer L6 takes .825 quarts of fluid. Filled as much as I could with Royal Purple through the axle shaft hole.
Replaced with new axle shaft since I didn't want to risk finding out I screwed the tripot joint by separating it and it landed in gravel when it came apart.
I wanted to pull the vent hose off the vent plug but I saw it was going to break the hose so I just removed the top cap and dripped the rest in. Took about 3 hours while I changed the rear diff fluid.
I plan now to remove the vent hose and replace it, and use the vent plug as my fill in the future. I will also fashion a bit of a dipstick to check fluid level through here as well.
So, maintenance preformed since last Thursday...
All upper and lower ball joints
Front and rear sway bar links with maxx links
Tie rod ends
Axle shaft
Front and rear diff fluid changes
Transaxle today and I think I'm good


Thanks for all the help!:tiphat
 

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2003 chevy trailblazer_lt_ext
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284 Posts
I wanted to throw in my experiences with a stuck fill plug since this thread helped give me some ideas in my quest to remove it.

Like others, I had a real hard time getting the darn thing off. So, after applying PB Blaster on the thing a couple days in a row I took a propane torch and slowly heated up the area around the plug, then the plug itself. I then also sprayed some more PB Blaster around the plug. It did not get it too hot - only about 3-5 mins total of moving it around the area.

Got a 6-point 18mm impact socket and attached it to a large extension - attach to the plug bolt. I can see where a 6-point socket is a good idea here. Using a 12 point may cause rounding off - then you would really be in trouble.

I placed a brick under the extension, resting it on the frame, just below the fill plug. Did this for stability.

I attached my 18" torque wrench to the extension and angled it so I can get to it from the from front of the truck. (I know that you are not supposed to use a torque wrench like this... but its all I had.)

I got in front of the truck on my back and slowly pushed the wrench. It finally gave way.

This worked even after an impact wrench failed. (Wasn't all that great of an impact wrench, though...)

I was really worried that the plug would break, but it is pretty thick after looking at it. I really dont think the fluid was ever checked, even though it went to the dealer for oil changes for most of its life. It will be checked at every oil change now that I am doing them myself.

Hope this helps someone in the same situation.
 

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2003 chevy trailblazer_lt_ext
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213 Posts
front diff fluid change

I changed my front fluid on the week end and luckily got my fill plug out with an extension and breaker bar.I was more concerned with the drain bolt,because I could only access it with a wrench.To my amazement the drain plug was only finger tight.The dealer had recently replaced a leaking yoke seal and had assured me that the front diff fluid would be changed,not just topped up.Since I was changing my motor oil I thought I would check the front fluid level at the same time.It looked black and was only 3/4 full.I replaced it with Amsoil Severe gear 75W90,same as I used for the rear diff.This just validates why I like to do my vehicle service myself.I would have put another 100 kilometers on that oil and lost a front diff in the process,thinking all was good.To change the front diff. fluid I used my Rhino ramps and removed the rock guard,but left the tire in place.One question that I have is should the drain plug(bolt)have any type of seal on it as mine does not? :thx
 

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2003 chevy trailblazer_lt_ext
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213 Posts
Drain Plug

Well since nobody helped me I checked and it seems that the drain plug should have a plastic seal.Mine must have been lost at the dealer more than likely.The bolt (drain plug) is fairly long and I dont know if that is the original either.I just wrapped the bolt with teflon tape and no leaks so far. :thumbsup:
 
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