Damnit...I killed something :(

[botboy]

Hi guys. Took my truck on a short roadtrip with my GF, julie to get a friends car that he bought off ebay.

Did a bunch of prep work to get the truck in shape to go down there...new plugs, oil, oil filter, tranny filter/gasket, synthetic ATF, synthetic gear lube in the rear, greased the zerts, etc.

Truck is a '72 C10, 350, TH350, 3.07 rear gears....had a small aluminum trailer to get the small subaru from iowa. Coming back from picking up the subaru the truck started bogging (or so it seemed) in 3rd, so I ended up doing about 150 miles from iowa to my home in 2nd at higher rpm's just to keep 50 MPH up. Without trailer, truck still seems to bog in 3rd, won't do above about 53 with my foot to the floor, and I know its not bogging. Unloaded, truck does 65 easy in 2nd gear but won't exceed ~53. Tranny fluid smells burnt (and damnit is mobil1 ATF Expensive!)

So what did I kill? I'm planning on dropping a manual in the truck (was planning on it anyway but this accelerated the timeframe for it) and since I'm going to sell the TH350 I want to be able to tell the buyer what exactly needs to be replaced.

Anybody want a TH350 core in the midwest?

[my new 72]

Sounds to me like you overheated the tranny and jacked it up. You should have installed a tranny cooler instead of that expensive synthetic ATF. It probably would have cost about the same initially, and less in the long run.

[Mudder]

Is that the right kind of tranny fluid for a GM?

[Longhorn Man]

You can run mobile one in a GM tranny.
Reading directly from the back of the bottle...
This Dextron=III product can be used whereever Dextron-IIE is aproved
Then goes on to mention 88 and newer fords, and then goes on to list advantages of there fluid.
botboy, what did your fluid look like when you dumped it out prepping for your trip?
Honestly, it sounds to me like you have an engine problem (carb or spark) and a tranny that is threatening to quit on you.

[dwaite72lnghrn]

My question would be when he added the new ATF was he sure the torque converter was empty other wise he would have mixed Dino and synthetic which depending on the synthetic might be bad. Was the level still good when you got back from your trip? Burnt smell ain't good. Auto to manual is a big job to do.

[Longhorn Man]

Mobile one can be mixed with no adverse effects.

[cableguy0]

you smoked the tranny. adding sythentic atf to an old tranny is a bad idea. changing really old fluid is also a bad idea. the synthetic atf is much slicker than the dino oil and it wont hold as much pressure in an old transmission because it pushes past the seals which lets the clutches slip and thats what happened. time for a rebuild

[botboy]

Not all clutches slip...1st & 2nd run just fine, like I said did most of the way home in 2nd gear @3000+ RPM and it was pulling hard like it always has. Engine is a mild 350, Edelbrock intake, freshly rebuilt rochest Q-jet, dual exhaust thru manifolds and upgraded HEI. I don't think I have a spark or ignition problem because it pulls like it *should* in 3rd gear in 1st & 2nd gears. Upgrading soon to custom TBI (After the tranny swap)

When I drained the old tranny fluid it looked pretty good but I don't know much about the truck (bought it out of an impound lot) so I'm always hesitant to trust the previous owners (Who I usually contend were morons anyways). Haven't had problems mixing ATF previously - worked great and even fixed slow shifting probs in my '70 Chevelle with a TH350 when that was replaced, again w/mobil1.

[1972C10]

Sounds like high gear band or the 3rd gear clutches.