Hard 1-2 shift in Chevy Blazer



I have a 145K on my 2000 Blazer. I had the transmission fluid changed/flushed about 6-7K miles ago.

I know the old adage about about not messing with an older automatic transmission that hasn’t been serviced, but the former owner seemed to be on top of things, and I had seen the ATF temps hit 230* during a long slow crawl in summer traffic, and decided that the fluid may have been compromised.

Anyway, here I am, water under the bridge.

My problem is that on two occasions the transmission has developed a very hard 1-2 shift. The first occasion was after a ~50 mile drive, after stopping at the end of the highway ramp to merge into local traffic the 1-2 shift was terrible and continued to be terrible for the few miles to my destination. My OBD-II device registered ATF temp ~180*, so not overheated. I stopped the vehicle and checked the ATF, level was fine. After a few hours, I got back in the Blazer and it was fine.

In fact, it was fine for nearly 4K miles, including some very long drives.

This past weekend I was headed home from a trip up north, I drove about 150 miles to a nearby small city, drove around in the city a bit, no problems, then back on the highway for another 40~50 miles to get home, similar problem–merging into local traffic from the highway off ramp I get a terrible 1-2 shift, continues to be terrible for the next several miles home. My OBD-II device registered 206*, higher then normal, but not crazy. It dropped back to under 200 during the few bad miles, but continued to be a very bad shift. ATF level is fine.

Today, drove fine on the way into work.

I have no idea what might be wrong, but I’m going drop the pan to change the fluid/filter this weekend.

I figure my worst case is a transmission replacement. All-Data DIY says price for a 4L60E is about $1800 and labor for replacement is about 9 hours. So I’m trying to ballpark my worst case (trans replacement) cost. Is $2500 about right?

I think the Blazer is probably worth it, I love it and it’s got nothing else much wrong with it at this point.

Is it worth it to bring it to a shop at this point where I don’t have a reproducible problem?