Transmission worries- 2002 TrailBlazer, Please Help!

[Ted Burns]

Car has 250k miles on it and I just purchased it little over a month ago.

New to learning about this vehicle and cars in general. My knowledge, if any, comes from experience and avidly watching Chris Fix and Scotty Kilmer videos on YouTube, all recently acquired knowledge. I am not a DIY.

Original owner sold me the vehicle. Original owner took pretty good care of the vehicle with exception of the transmission. Transmission was rebuilt 12 years ago when the vehicle had only 75k on it. No history of subsequent replacing the fluid or flushing of it!

I've performed cold and hot checks and the fluid is brownish in color with a slight sign of red. I guess that it's brown-reddish with brown predominating.

While driving, there are no signs of slipping or other obvious signs of transmission problems that I can ascertain.

It has been 175k miles SINCE the rebuild. I got a BlueDriver yesterday and there are no transmission codes.

Any suggestions what to do in this scenario would be GREATLY appreciated!

 

[Reprise]

Sounds like the trans is operating normally; you're just worried about the fluid condition.

I'd definitely replace the fluid. Even a simple pan drop / filter replacement / refill with 5qt of Dexron VI fluid would be great. This is something you can do yourself, too (you do need a ratchet / sockets, and a 3/8" torque wrench would be good, too).

Get the 'deep pan' filter (look under your truck; you should see a pan depth of about 3" or so.) I've never seen one of our trucks with a 'shallow pan' (about 1" deep), but do check. It'll likely have a drain plug, too (it may be overtorqued; GM tended to do this at the factory)

If you want to replace 'all' of the fluid, there's a procedure many use here to do that (but you'll need 15-16 qts of fluid, and disconnection of the fluid return line - you can find the instructions / photos in the post). Do NOT have a shop reverse flush it; too many have bit the dust doing that. You should still replace the filter, too, if it's got 175K miles on it.

Now, there is a school of thought that says with that much mileage on the fluid, you may as well leave it as-is, as new fluid may loosen up stuff and clog the filter (even a new one). So if you wanted to go that direction, you wouldn't be the first. But if it starts acting up (or you plan on using this as anything more than a grocery getter)... get the fluid / filter changed, for sure.

Finally, I'll say this, in hopes it doesn't scare you too much... the average service life of a 'factory' 4L60E is roughly 200K. It can last longer - but if it goes south, figure that you got the life out of it at that point. To replace it will run $750-900 for one from a junkyard, and to rebuild yours will run $1500 on up. So that becomes a decision on what the truck is worth to you, at that point. If it's rebuilt, with the weak points addressed, it'll outlast the rest of the vehicle (e.g.; much longer than 200K) with nothing more than fluid / filter changes every 35-50K.

Is yours a 4WD? If so, change out the transfer case fluid. It needs to be changed every 50K with GM Auto-Trac II fluid (blue). You'll need 2qts. Lots cheaper than a T-case replacement.

 

[mrrsm]

Welcome to GMT Nation...

Another Pro Mechanic worth searching videos on is Eric "O" from South Main Auto. Here he is working on our style of GMT 360s (Trailblazer/Envoy/Ranier) while Changing the Fluid and Filter in 2003 Trailblazer 4WD with the 4L60E Transmission:

You can purchase the correct ACDelco Transmission Filter Kit via Amazon at this Link:

Amazon.com: ACDelco TF289 Professional Automatic Transmission Fluid Filter Kit: Automotive

Buy ACDelco TF289 Professional Automatic Transmission Fluid Filter Kit: Filter & Gasket Kits - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

... as well as the Perma-Tex HIGH-TACK Spray Gasket Adhesive:

Amazon.com: Permatex High Tack(TM) Spray-A-Gasket(TM) Sealant (80065) : Automotive

Buy Permatex High Tack(TM) Spray-A-Gasket(TM) Sealant (80065): Gasket - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[Sparky]

Just change the fluid and go about your day. It is an old wive's tale that new fluid will kill a transmission.

 

[HARDTRAILZ]

Its not the fluid that hurts them...its the power flushing places do. Just do basic fluid n filter swap and all is good

 

[Mooseman]

Search on YouTube for "may03lt transmission " and you should find a couple of videos on how to do a full fluid exchange using the cooler line. Makes the pan drop so much less messy and you will only have fresh fluid in the tranny.

And yes, shops that use power flushing machines WILL destroy your tranny.

 

[Reprise]

Another Pro Mechanic worth searching videos on is Eric "O" from South Main Auto.

+1. I think Eric is the best mech on YT. Briansmobile1 is very good as well.