Okay, so I just bought an 87 k5 blazer. Pretty good deal but this little/ or big,,hopefully little issue has me scratching my head. As I was driving it home, about a half hour in going down the road at about 50-55mph it was like somebody just put it in neutral. No clinking noise, no knocking noise, nothing.. just pretty much went into neutral, of course it was still in drive. Any way, called a tow truck loaded her up and was off. Got home got it off the tow truck and just out of curiosity tried again, started the truck, put er in drive and she drove away. Any insight on this issue will help a LOT! Thanks in advance for any help,
-Kyle

 

might be a long shot but ive seen this before on a late 90s van. same crap would drive around fine for a hour or so then just stop working. ended up getting the trans rebuilt and the problem happened again. it ended up being the transmission cooler that is part of the radiator was clogged restricting flow.

we ended up just putting a aftermarket cooler in front of the radiator and it was fine after that

no promises thats the problem, just throwing a idea out there

 

how does the fluid look and smell? dark and burnt?

 

Thanks for the insight abig84. I'll look into that. And no fluid is fine. Nice reddish color

 

*Moving to Fullsize K5 Tech*

Have you checked the TV cable adjustment? Google should be all that is necessary to find the particulars so I won't go into it here.

Aside from that, you are going to want to monitor the line pressure both when cold and when hot. You will need a transmission pressure test gauge that you will install into the test port on the driver side of the transmission.

 

The TV cable is a good idea to make sure it's adjusted properly, no doubt, but I really don't see where it would make it jump into neutral. I would try this, check the shift linkage to make sure it's set properly. If your TV cable was out of whack, you transmission would either shift too hard, too quickly, or shift too soft, and too late. I had this problem, and killed a transmission before I figured it out. My truck is lifted, so that may be a factor another old problem, which was transmission jumping into neutral. I adjusted the linkage properly and no more issues.