96 chevy k1500 tranny problem

[evans_usmc69]

I was driving down the road yesterday and I completely lost third gear. It shifts fine from park to 1st, 1st to 2nd, but when the transmission shifts to third, its the same as shifting into neutral. Anyone have any idea what would cause this?? I am not sure when the last time the transmission fluid was changed. I just got this vehicle a year or so ago, guess I should have asked. Thanks in advance.

Travis Evans

[jdmccright]

You should have some stored trouble codes. Beg/borrow/buy a code scan tool and post the codes back...but doesn't look good.

Definitely look at the tranny fluid. If it is low, clear to brown in color, or opaque, it is overdue to be changed. You can try a fluid change, but from your description, it's not the fluid...at least not anymore. If it had been shifting hard before this, those were your warning signs. Good luck!

[Merc 1500]

So worst case scenario, what do you think that is.? Because I have that same exact problem with my '93 K1500. And I've changed my tranny fluid, then checked it since then and its running clean.

[jdmccright]

Absolute worst case is you've lost one of the internal clutches, meaning you get to have the tranny rebuilt or replaced.

Less than worst case is you've lost a valve control (2-3 shift) solenoid or the valve itself or a check valve in the valve body has failed. This can be fixed by rebuilding only the valve body (meaning the whole tranny doesn't have to be removed). But a competent transmission shop should be able to tell you the extent of the problem.

If your check engine light is on (yours is OBD-I, so the codes can be retrieved w/o a scan tool), then hopefully its just a solenoid.

Extra thoughts...was the fluid low when you changed it? If so, are the any obvious leaks? If not, then you should check your vacuum lines from the transfer case switch mounted on the driver's side (three tubes coming out of the top). The internal seal can fail, sucking tranny fluid into the vacuum lines and into the front diff actuator diaphragm, the acumulator bulb and also out the tranny vent tube. The other possibility is that the seal between the tranny and transfer case has failed and fluid is leaking into the case, draining the tranny. Did the transfer case appear overfilled?

Hope this helps!

[Merc 1500]

Thanx for the help man, I'm saving up some money to take it to a tranny shop right now and keeping my fingers crossed that it isn't something real bad.