Gearbox heating up at top speed (1 Viewer)

[Adam Khan]

Hi. Gearbox of my 1hdft 1995 heats up when driven over 105km / h for long. Checked up some trouble shooting tips:-
1) Gear oil Check
2) Hydraulic Fluid Check to include water pump too.
3) Brakes
Will someone plz help me out about serial 2 above .
■ Where is this hydraulic fluid filled in a 1hdft?
■ What all comprises the hydraulic system of 1hdft?
Regards

 

[gnarlynick2072]

Auto or manual gearbox?

 

[Adam Khan]

Auto or manual gearbox?

Auto gear box

 

[cme4lyt]

How do you know it’s heating up/over heating ?

 

[Adam Khan]

How do you know it’s heating up/over heating ?

During driving it gives a lot of heat inside and feels very hot when touched which gives me an idea that it's over heating and the rig runs as if something is holding it back

 

[Whiskerz]

It will be hot to the touch. The fluid temperature is what is important.

 

[Adam Khan]

It will be hot to the touch. The fluid temperature is what is important.

Ok. I checked the fluid. That's ok even after a 5 hrs top speed drive

 

[Adam Khan]

The rig also runs as if something is holding it back. I just changed genuine oil, oil filter and air filter and the engine sounds perfect too

 

[Kernal]

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[J2P]

It sounds like you are a little confused. How long have you had the truck? The tranny is filled through the filler tube but you need to check your level first and if the fluid is burnt. Maybe you got a new exhaust that runs inside the frame and the heat from the turbo at full boost heats up the floor and the shifter? Only a tranny temperature gauge will show if the tranny is running hot and I doubt you have one installed as they don't come from the factory.

 

[Adam Khan]

It sounds like you are a little confused. How long have you had the truck? The tranny is filled through the filler tube but you need to check your level first and if the fluid is burnt. Maybe you got a new exhaust that runs inside the frame and the heat from the turbo at full boost heats up the floor and the shifter? Only a tranny temperature gauge will show if the tranny is running hot and I doubt you have one installed as they don't come from the factory.

It's been two years I have this one. Before that I had a 1fzfe. I checked the gear oil, it retains viscosity, its clean and also shows accurate levels.
Your point of exhaust running inside the frame heating the floor and shifter sounds convincing to me. I will check it up and then post response.
Thanks a lot

 

[Adam Khan]

Hi All. I have recently changed all suspension and hydraulic lubricants on my 1HDFT. But changing liquids has not reduced heat generation on Gear box.
Next I am going to check the exhaust whether it is running inside the frame heating up things. Will update on any discovery.
Regards

 

[bug616]

Unless you have a temperature gauge telling you the gearbox temp or your ATF warning light is coming on, you can’t possibly know if the gearbox is running too hot.

 

[pawnthatdude]

During driving it gives a lot of heat inside and feels very hot when touched which gives me an idea that it's over heating and the rig runs as if something is holding it back

The exhaust is hundreds of degrees hotter under normal conditions than even a badly overheating transmission. Don't know how the diesel 80s are for exhaust routing, but my passenger floor gets mighty warm on a long drive.

 

[FirstToy]

I believe the floorboard heat is more due to the cats/exhaust just under the floor than the trans.
I could be wrong, but I think the auto trans typically does not run hot even working hard. It has the oem cooler as well.
Does the 1HD run a trans cooler?

Check your trans fluid. It should be red. The dye turns dark if overheated.

 

[Adam Khan]

I believe the floorboard heat is more due to the cats/exhaust just under the floor than the trans.
I could be wrong, but I think the auto trans typically does not run hot even working hard. It has the oem cooler as well.
Does the 1HD run a trans cooler?

Check your trans fluid. It should be red. The dye turns dark if overheated.

I have checked the trans fluid. Its red, the same color as it comes. I will also check the exhaust line as you said and then let u know. Thanks

 

[bug616]

I believe the floorboard heat is more due to the cats/exhaust just under the floor than the trans.
I could be wrong, but I think the auto trans typically does not run hot even working hard. It has the oem cooler as well.
Does the 1HD run a trans cooler?

Check your trans fluid. It should be red. The dye turns dark if overheated.

1HD has no trans cooler other than in the radiator. The A442 is known for getting hot if running bigger tyres, lots of weight, or fluid is bad etc. They benefit hugely from an additional cooler

 

[Zjohnsonua]

Hot means different things to different people. Get a thermometer and measure the temp in the area you're concerned about.

As a reference, the trans tunnel on all of my cruisers is warm enough to make my phone go into thermal protect mode if I leave it there long enough, but there's nothing wrong with the trucks. Toyota just didn't deem it necessary to apply heat shielding in that area, and neither do I.

 

[J2P]

1HD has no trans cooler other than in the radiator. The A442 is known for getting hot if running bigger tyres, lots of weight, or fluid is bad etc. They benefit hugely from an additional cooler

My 91 HDJ81 had a factory external tranny cooler, I think most had them.

 

[bug616]

My 91 HDJ81 had a factory external tranny cooler, I think most had them.

That’s interesting. None in the UK have any external trans cooler as standard. Must be a market specific thing. Although IIRC I think there was a ‘towing pack’ or similar that included a trans cooler....