Okay, did a body swap on a 77' last weekend. Got all the bugs ironed out and took it for a ride last night. Went about 15 miles and the truck stopped shifting and dropped speed. Pulled over, added tranny fluid and truck took off, but did not act like it was in first gear. Towed it home,

This morning, found blown transmission line to the tranny cooler, replaced it and added fluid. Truck goes into all gears, but you have to rev the motor high to get it to move (almost as if you were starting in fifth gear in a manual)... Does this in all forward gears and reverse.

Any ideas?

 

my dumarse uneducated guess is the clutch packs are no more.
That is if the fluid is topped off and it isn't still low.

 

That quick? It's driving one minute then not the next? Never had this happen with an automatic.

 

Anything I can check to diagnose the problem?

 

I don't know for sure. But yes I think that could very well happen.
You didn't say how much fluid you had to add back in
And I'm not familiar with the history of the transmission, so I'm only guessing.
If it was weak/old / high miles to begin with? If the fluid was old and nasty to begin with?
If it started puking right away it could have been empty in 15 miles probably less.
No fluid in it while driving obviously isn't a good thing and it could have kept you going
for a mile or more with nothing in there and than poof.

You could check to see if a vacuum line busted off someplace.
If all lines look good drop the pan and look in it for any possible clues.
It's been a long time since I dealt with auto transmission problems. Fortunately I suppose; since my vovo one is high mileage and doesn't even have a filter :/
But usually they either work or they don't with these types.

 

Just got the truck, so hard to say. Had to add a quart the first time. All.drained out after that

 

If it was completely empty and driven on as you imply, than only a rebuild is going to fix it. Someone else hopefully will over rule my opinion with better news though.

 

Tha ks for the input.

 

Could a bad cooling line really cause the tranmission to die?

what if there is air in it causing it to not shift right?

 

Like he posted? Absolutely. With no line pressure, but rpm, it will attempt to apply the clutches, they'll just slip, and burn. It's not like it popped the line and died immediately, I'll bet, he revved it quite a bit, then added fluid, drove some more... poof, clutches gone.

 

Wow!

That's Terrible! ... Glad I drive a stick even gladder now!


Except, If I keep grinding my four gear

 

Yes, manuals are far more durable and able to take abuse better for the most part. Lose fluid in an auto and it's over pretty quick.


Lose clutch in a manual, insert beer cans, keep going lol.

 

Was only a quart down. The dipstick read low, never out.

 

Climbed underneath the truck today. Tranny is a C6 not a C4 like I thought. We serviced the tranny, added 6 qts. of fluid and she is back up and driving. The wife insisted we service it and did most the work herself, so she is the one that fixed it. Thanks for all the input.

 

Lucky guy, found keeper and married Her!