1984 Corvette 4+3 not working
 

Ive read post on here before, didnt find anything useful, I was driving down tghe road with it engaged and all of a sudden it disengages on its own i slow down it goes back in and i go for about another 10 minutes and it did it again, then it would disengage and try to go back in and come right back out over and over again, not staying engaged, i checked the fuses, the light still comes on and stays on, even if it is not engaged, i changed the fluid with some lucas trans slip stop and some royal purple max ATF, it started working again then about 10 miles down the road started doing the same thing, it might need to be topped off with fluid just wandering if anybody else has had this problem, car just turned over 40xxx.

Low fluid could cause that but it could also be broken/worn internal parts. Could also be a bad solenoid. Also check the wire harness connection. The consensus some years ago with regard to fluid for the 4+3 was to use only DexronII/III non-synthetic ATF. GM/Doug Nash never recommended the use of additives or friction modifiers in the OD.

Thank you for the reply, where is the soilnoid? I flushed out the cooling lime when I changed the fluid, so it might just be low on fluid, it was working perfect after I change the old nasty brownish fluid and it shouldn't be worn, only has 40xxx.

It's screwed into the side of the valve body (under the filter). They rarely fail though. It's either low on fluid, a loose connection, or it may need a rebuild.

When I went to change the fluid, there was a bolt resting on the filter, with a 10 mm head I took it out and it looked fine I put it back in the whole and the threads were fine I tightened it, could that be what holds the soilnoid, if so that may contribute.

My 84 did that. It was the insulation on the wire harness at the 4+3 was compromised due to oil saturation from a failing rear main seal

What did you do?
 

So what did you do? Replace the harness or able to clean it and reinsulate it?