Just recently purchased a wholesaler special 1991 Corvette Automatic C4 that was meant to be a project car, but was also supposed to drive itself home. Think the transmission bit the dust, but I'm really just looking for advice on shorter term / cheaper items to check off the list before I go for the full transmission rebuild. It's currently sitting in my single car garage on jack stands while I check everything out and tick some of the easier items off the list.


Car ran fine during the (brief) test drive, the engine still sounds great, there are no engine codes being thrown (yet), but an ABS code. I signed all the paperwork for the dirt cheap C4 and drove about 15 minutes before I lost all acceleration and braked / coasted safely to a stop. There was a slight burning smell that dissipated very quickly - the transmission fluid looked and smelled completely fine. Sat in park for a minute before trying to shift gears. Not sure how level the ground was, but the only thing I could get the car to do was roll slowly backwards and park.

Got the thing towed back home. Tow driver said he was able to throw it into neutral no problem. I messed with the car a little bit before putting it into the garage.

I was able to give the car some small, but noticeable acceleration in some gear once or twice - not sure which gear. Was likely either overdrive or 1st. It didn't last long as my driveway isn't particularly long and it wouldn't happen every time. The two times it WAS able to give me some power, I had STOMPED the brakes before it lurched forward. An ABS dash code is on - haven't had a chance to check it yet.

The shifter action feels fine. The engine will change it's idle rpm when I shift from park to reverse to neutral. The TV cable seems completely fine all the way to the transmission lever, which moves normally from shifting. The wheels just don't get any power.

For clarity of anyone that comes across this, the transmission for this model is the 700R4 / 4L60 (no e). Like I said above, I think it's the transmission or some sensor, but the fluid looks great and I don't know where to start for sensors that control the transmission. The slight burning smell that went away makes me think the clutch packs went.
I guess I'm hoping to find out if there are any sensors or fuses that would be the first checks. This is my first Corvette and I'm excited to dig into it.

The engine runs great, checked the MAF and TPS and both seem fine. Haven't checked the brake sensors yet, TCC is my biggest question as I'm not sure how it communicates with the mostly mechanical transmission.

Any thoughts?

 

Your post is a bit confusing. You need to clarify some things. When you say "...but the only thing I could get the car to do was roll slowly backwards from park. Was either only able to get it into (Park and Neutral) or (Park, Neutral, and Reverse)." Are you saying that the actual shift leaver won't move to other gear selections or the transmission does nothing when you select D? "Shifting feels fine. The engine will change revs when I shift into different gears" Elsewhere you say you can't get the transmission to do anything. Which one is it? Won't shift or ot shifts fine?.

 

The shifter **** and TV cable moves fine. I can move it in a normal way into every gear. The engine will change rev up or down as I move the shifter.

No power will go to the wheels.

 

Still hoping to find some alternatives to transmission work before she hits the shop. Would love to hear any anecdotes of repairs.

 

I tried but I am completely lost by your description of the problem. You say the transmission shifts in all gears and the engine changes revs as you shift. Then you say no power is going to the wheels! How can the trans shift through the gears and change revs if the wheels are not turning? Maybe someone else can decipher this.

 

I mean, off the top of my head that could mean a blown rear diff, a broken output shaft, maybe a faulty VSS... lots of things. I just dont have insight into the specifics of the C4.

 

Made a few changes to the original post, still hoping for some other leads to chase before I drop the transmission later this week.