I think I ruined my transmission :(

My transmission went out on me yesterday while hunting. Kept it at about 85mph on the highway for about two hours, jumping between 4th and 5th gear the whole time. Then it was a drive up a steep mountain in 4wd, which is when the shifting started to be really hard. My a/t oil light came on right as the truck was having a hard time shifting at all. Looked under and the whole underside of the truck was soaked in transmission fluid. Managed to limp back to a nearby truck stop at the bottom of the mountain at about 30mph.

I realize now after talking to a few people that I just ran it way too hard and it probably puked up all of its fluid.

Any chance it’s salvageable? I’ve never done a drain and fill but some are saying I should try putting fluid back into and see what it does.

Any ideas on what I should do?

 

Were you towing or something? It should have absolutely no problem holding 85 mph up a mountain pass even. It sounds like the leak happened first it ran out of fluid and overheated. Likely is cooked though if it was puking that bad. Only way to tell really is to fill it up and see if it acts normal again after finding out where your leak is

 

About the only way it can "puke" fluid is from the vent.
And the vent is right behind the center of the engine. At the top of the bell housing.

I'm with @Speedytech7
I bet you had a leak first.

 

85 is absurdly fast in a Tacoma, even on a flat road. Can't imagine going that fast up a mountain.

 

Montana speed.

 

???????? 85?

No problem hitting the speed limiter at 106 mph on flat ground, even w/ 1000 lbs of cargo/tools. Maybe around 4.5K rpm. There's still some power left, could probably hit 110-112 if there was no speed limiter.

 

I've run out of speedometer plenty of times, thankfully my aftermarket ECU keeps reading so I have numbers for the data log.

 

It wa

It was 85 on the highway but then about 10-15 mph in 4wd going on a dirt road up the mountain. I should have clarified

 

you live in Texas and 85 is fast?

These are modern vehicles, they can handle that speed.

 

To maintain 85 mph in a 2nd gen Tacoma will mean about 3500 rpm; only about 2500 rpm at 65. You don't mention altitude, but much above sea level and the engine is already working harder, and HOTTER because you lose about 3% of your power for every 1000' above sea level.

I'm betting you did this in OD which also means more heat. You most likely overheated your transmission fluid and fried the transmission.

I've spent some time in the western states such as Texas, Utah, and Montana which have 80 mph speed limits on rural roads. But just because you CAN legally do it and the vehicle WILL go that fast doesn't make it a good idea. It's less of problem if you're below 2000' above sea level, but at 5000' more you need to slow down and use lower gears.

Fuel matters too. In many higher altitude places, they sell 85 or 86 octane fuel as Regular. NEVER buy that fuel unless you have an older vehicle with a carburetor. The owner's manual says use AT LEAST 87 octane. That means even at altitudes where 85 octane is regular. Using lower octane fuel means more heat. It's a good idea to use 89 or 91 octane at higher altitudes.

 

I strongly disagree...

85mph in a 2nd gen tacoma with the automatic A750F (0.716 ratio) would be about 2,500rpm. Well within it's comfortable cruising range. Also, the torque converter locks up when cruising eliminating that heat.

85 octane is fine, octane is just a number relating to fuel pre-combustion or detonation. In a non-forced induction motor (no turbo or supercharger) you typically dont need high octane. At higher altitude there is less combustion pressure and less likely to pre-detonate/knock. Thats why higher altitude places have lower octane. Engines with high compression ratios will require higher octane, but the 4.0 aint one of them...

The Tacoma is not a delicate flower, it's a workhorse and can be treated as such.

 

This thread has gone sideways... here is what I think.

-The AT temp light comes on after the trans temp is already at dangerous levels. The fluid is cooked, and should be replaced asap.
-The leak indicates you ran it low on fluid, starving the transmission cooling system and likely the clutches as well.

The trans is likely done. You ran it low on fluid and cooked the clutches. The way you drove it should have been fine (as long as you weren't towing) you likely have some sort of existing leak or failing cooling line or seal.

If you are comfortable pulling the trans source one on car-part.com and swap it. The A750F is known for being robust.

 

It takes more then a page for a thread to go sideways. lol

OP, change fluid then drive it. Then you'll have you an answer.

 

.
Ever driven a pre-Tacoma PU? They make Tacomas seem like 1st grade ballerinas. Ok, they do work well and I did sell my 1st Gen to get the increased towing capacity of a 3rd Gen to tow a trailer with and it does work well, but I think they are delicate. Heck, a little mouse can disable the thing by chewing through just one little small gauge signal wire, and has those wires all over the engine and under the body. Now that’s delicate!

OP- I didn’t read through this whole thread, but is it possible something forward of the transmission like a cooler line got damaged and with the speed you were going all the oil would’ve flown back towards the transmission. It sounds like the damage started to happen on the freeway, as you mentioned hard shifting.

 

I had a 94 Pickup with the 3.0. They were built different, but also had no power.

 

Sorry, I wasn’t comparing how well it works to being not delicate, The third GEN are definitely more powerful than those older trucks. But in terms of survivability and not being easily broken, I think we know which one is really more delicate.

 

You said this happened during "a drive up a steep mountain in 4wd"... How steep are we talking? Were you in 4-LO? If too steep and not in 4-LO, would cause the trans to overheat.

 

Usually when the at light goes on its too late, warping has happened and a bunch of no bueno. Ig you can put some Lucas and see the damage

 

Well… I took it into my mechanic and he said a cooler line had been rubbing against the sway bar and caused a hole in the line. So I must have been losing fluid the whole time on the highway and possible could have had a slow leak days before that. He’s saying that the transmission is likely ruined but that we could try putting oil in it and see what happens. Should I spend the $800 on the new lines/filter/oil or just pay the $3200 he quoted to stick a used transmission with 116,000 miles in there?

 

For that much, get a quote for a transmission rebuild on your current transmission. https://www.atra.com/