Hey all, I'm new to the blazer forums. I picked up a 97 blazer 4x4 4 door with the 4.3 vortex and the 4l60e tranny. It has 122k miles on it, a gas leak and a whole lot of tranny leaks (main seal, etc). That aside though, when I drive the blazer for a decent amount of time doing 50+ mph, it will shift real hard from 1st - 2nd gear.

I have been looking this up on the web for a little while now and i am almost positive it is the valve body in the tranny. According to some "experts" there are two different types of metals that wear differently, so when the engine detects a "slip" it will push more tranny fluid between these metal pieces causing the hard shift. It also throws the 1870 code when it detects 2 of these hard shifts during a cycle. In the chance that it could have been the transmission filter, I replaced the filter and tranny fluid as well as the transmission pan gasket. It shifted great at first but to no avail the problem still persists.

I have also read something about the TPS going bad? I don't really know, but what i do know is that purchasing a new or revised valve body is going to be about 300+ bucks, plus ill have to replace all the bad gaskets which will require me to drop the tranny. It also does not look very easy to change the valve body because theres like 50 bolts in there lol. I might as well just replace the tranny right? If i did go that route what tranny should i replace it with? I want a reliable tranny that isn't known for stupid things like this. I have heard that the 700r4 is a good one but isn't that the same thing technically as the 4l60e? Any help would be greatly appreciated. Thanks!

 

One thing that you can try, which worked for my Blazer, is putting in Lucas. Should be able to pick it up at an auto shop, or even walmart, for about $12. After I put it in mine, the hard shifting between first and second stopped. Its worth a shot, and if it works, could save you money compared to getting a new or rebuilt tranny.

 

It sounds like this transmission needs to come out anyhoo... This seems like a scary job but really it is not. If you are going to do this repair, I would recommend you get the front end up in the air and on jack stands. This will allow you to clean the area with a pressure washer. Working under a dirty car or truck is the worst.

 

Thank you for the replies, I have heard about trying Lucas in it so as soon as I get a chance to do that I will. I just do not know if I should try and get a different tranny or just replace the seals, I have to drop it regardless. I will definitely use a pressure washer and clean it out when It's on jack stands.