Tranny oil level

[ClintThrust]

My transmission overheats almost immidiately when i start up a hill. on level ground its fine. Ive been told that an incorrect fluid level could cause it to overheat. when i check the dipstick hot its pretty close to the hot indicator, but when i check it cold its waaay over the cold mark.

which mark should i go off? the cold ones a lot easier for me to check because i don’t drive the bus a lot, but im hesitant to take that much fluid out and try to run it (it must be a few quarts at least)

By the way, the performance of the gearbox never changes when its overheating, although i stop it when the temp gets all the way up.


Follow up question, the fan turns on sometimes on hills and cools the transmission down, but rarely. is there any way to trigger the fan clutch manually?

 

[s2mikon]

Always check and adjust fluid level when at operating temperature. What fan control do you have? Air clutch, viscus drive or hydraulic. What temperatures are you seeing? What transmission do you have?

 

[ClintThrust]

Im not sure what type of fan clutch it is, its silver and it has fins and i don’t see any wires or hoses coming out ofit. ill hear a click and itll come on pretty sudden, and turn off the same way.

its an allison transmission, not sure which model. the gauge goes up to 350 and itll usually get there within a few minutes of climbing unless the fan turns on. never and leaking or grinding or slipping.

 

[s2mikon]

350 is way to hot. Allison states that 250 is the max. Your transmission is cooled by the engine coolant and if your fan is not working properly it will overheat your transmission. Can you post a picture of your fan clutch? You need to get this fixed before you ruin your transmission. How hot is the engine getting?

 

[s2mikon]

I think you have a viscus fan drive and the clicking may be unrelated. IDK. It may be time to replace the fan clutch. I need more information.

 

[Bert06840]

Yes. This is no good.

Your converter is slipping or your brake bands are slipping up; if you are lucky your cooling isn’t working.

As said. Get this fixed immediately.

I would wager it’s a cooling issue. Add a big transmission cooler even after you have figured out what is going on.

 

[Cheezewhiz]

It's a ghetto solution, but I had a truck with a lightswitch bolted to the dash.

It flipped the radiator fan on and off, straight manual control.


I only almost overheated it a couple times!

So yeah, it can definitely be done for the price of a switch you can scavenge out of something and some wire.

Getting the proper temp control switch is better of course

 

[ClintThrust]

the engine was staying at 150, i replaced the thermostat and now its kind of erratic, usually around 180. i don’t trust my gauge anymore ive found that a good tap can change the temp it displays drastically.

if there’s a way to hook this fan to a lightswitch that’s absolutely the kind of thing i would do.

 

[s2mikon]

More questions. Do you have an infrared temperature gun? If you have a fireplace, school bus or cats you should. This will allow you to measure surface temperatures of your radiator top tank, bottom tank, thermostat housing, transmission cooler lines, tires you name it. If the engine is running 180 when the transmission is running at 350 something is really off. Either the transmission gauge or sender is bad or the transmission is toast. One of the lines from the transmission should read with the infrared gun close to the trans gauge in the bus. The other line will be cooler. Get one if you don’t have one and drive it until your trans gauge read about 200 to 225 park in a safe spot and read both lines and see what you have. Try to read it on the metal not the rubber. If you find a large discrepancy, your trans gauge reading higher than the infrared it is time to fix your gauge. If not you have other problems.

 

[ClintThrust]

i do have a temp gun. ill give it a shot. ill try it on a cat too.

 

[s2mikon]

Mine will chase it until they drop. Shine it on the ceiling and they are as frustrated as a eunuch in a harem.