98' 4Runner Transmission issue.

[Joecartoon]

Couldn't find a post with the exact issue, but it shouldn't be too hard to get an answer. I've reached 190K on my 4runner, and have started to notice that within the past 5-10k miles that after ive been driving for any length of time, or go up hills, or anything that might put the transmission under stress, or make it want to downshift that it will have trouble shifting out of overdrive, the transmission will feel like it slips a few times then finally catch. also it will occasionally do this when in 4th gear shifting into overdrive. if i sit at a light for a minute then accelerate it will feel sluggish for a second then continue.

this only happens after the car is fully warmed up ( drives fine when not fully warmed up), also only happens when in overdrive, or under hard acceleration ( above 40) so it seems that 1st-4th gear are fine. it feels like the transmission is overheating and is having a hard time shifting under hard acceleration, so ive been cutting it back lately, and i havent been having the issue. so im not sure exactly what is causing this.

i took it into Toyota today, and after a quick drive they said they thought it was the pump, i assume they mean the coolant pump? and if so would it possible to fix? or would a tranny cooler work in place? they checked the transmission fluid, and did note that it was somewhat dirty (changed 30K miles ago). but before i made any decisions i figured i'd see what people had to say, because I'm going between it being the pump or an overdrive solenoid.

so any help would be great, thanks!

 

[4-Ripcord]

did you have the fluid changed while you were at the dealer if they said it looked dirty?

Couldnt hurt

 

[Joecartoon]

they said they were worried that the viscosity of the fluid might be holding the transmission together, and that flushing it, or changing it might cause corrosion of the transmission. and before i did i figured i would ask if that was a risk worth taking. i live 10 minutes from the dealership, so i could go back tomorrow and have it done, if you dont think it would hurt.

 

[Joecartoon]

Okay, figured its well past due to give an update. Turns out that the problem wasn't in my transmission at all, it actually was in the ignition wires. they hadn't been changed despite being told they were before i bought my 4runner, only the plugs had been. and the problem i was having was because the wires were going out, and when they were getting hot, they were causing the spark plugs to always fire, and the engine to lose a lot of power, especially right around the shifting points where the RPMs where higher. so that rough acceleration was actually just the engine missing pretty bad. my friend actually recommended driving without the heat on, and what do you know? less pull on the engine actually helped it to not fire as bad, so since then I've replaced the wires, put in iridium plugs, a new alternator, and a new battery, and my 4Runner has been running better than it ever has since i bought it. and the transmission is actually doing great! too bad the guy who drove my 4runner at the dealership didn't know what he was talking about.. oh well, but i hope this helps!