Transmission running hot on highway (1 Viewer)

[Black94Prado]

Hello again, back at it with more questions. Truck in question is 1994 Land cruiser Prado with a343f auto transmission.

I'm currently driving from Canada to Mexico and Central America (hopefully). I'm doing my daily wifi stop, just got into California today. Deleted EGR before I left put in egr gauge and also while doing a transmission service I put a trans temp gauge in.

Anyways long story short, off road it's running good, max about 180°, stop start traffic is good, about same, slow is good, medium speed good, turning point is around 90km/h. Transmission goes from 187°ish sometimes up to as high as 210°. I've been playing around with it and seems to stop creeping there but if I do 100km/h or more it'll slowly creep above that. Isn't this backwards? Shouldn't it be running cooler at highway speeds? It's not even hot out, in fact going through the high desert it was literally freezing out.

Is this maybe a t-stat? Or a fan clutch? Or is 210° within operating range? Forgive my ignorance. The truck is pretty heavy, it has a full drawer system, roof tent, maybe 700lbs total extra weight, 2.5" life on 33's. No external cooler. EGR temps are great.

On that note does anyone know someone in Las Vegas area or southern California or maybe even west arizona that can put together a transmission cooler with little notice? The plan is to take the rig through central america as well and maybe south so it's only going to get hotter. I don't mind keeping it on the backroads but sometimes highways are required.

Thanks for any help! Will check back in when I next have some internet.

 

[AirheadNut]

That does seem backwards, since at highway speed the torque converter should be in lockup and therefore the transmission should create very little heat. What did your transmission service consist of? Where is the sending unit for the temperature gauge located? An auxiliary cooler would definitely help keep temps lower, but I don't think that 210ºF is particularly concerning. I wouldn't be comfortable running much higher than that though.

 

[Black94Prado]

That does seem backwards, since at highway speed the torque converter should be in lockup and therefore the transmission should create very little heat. What did your transmission service consist of? Where is the sending unit for the temperature gauge located? An auxiliary cooler would definitely help keep temps lower, but I don't think that 210ºF is particularly concerning. I wouldn't be comfortable running much higher than that though.

It was just removing pan, filter, solenoids, cleaning everything out fully and doing a full fluid flush. After a bunch of reading I did decide to put the sender in the pan beside the pickup, so temps are even hotter in the lines of course. That temp only creeps up to 210 and back to 180 and fluctuates after about 30-40 minutes of highway driving though. Once I hit slower speeds it backs off within a minute or two.

 

[renago]

do you think 210 F , 98 C is hot ?
or better too hot ?

 

[Black94Prado]

do you think 210 F , 98 C is hot ?
or better too hot ?

Well with the ambient temperatures being pretty cold where I'm driving through I'm worried it will only get hotter down south, seems the transmission guys I've spoken to think 210 is warm.

 

[Squash]

That is an acceptable range and you can worry free hit 220.
You could see 230 and not really worry for short bursts. Now if you are really climbing or towing and heading to 250 then definitely something needs to be done.
During a recent trip to bike the Squamish area I engaged low transfer case and either 2nd or 3rd gear because the logging roads are steep and we were loaded with 5 people, bikes and gear. Basically driving based on tranny temperature and EGT.