Altitude

mistersnowman97

mistersnowman97

New member
Goin up to tahoe in 2 weeks. (hopefully there'll be snow). Anyway, last few times I've gone up there, on the way up the truck runs great. (it stays at 65 with my foot on the floor). engine temp always runs normal. but when really start gettin up there, my "A/T Oil Temp" light comes on. It goes away if I just pull over and turn off the engine for a sec. I can drive for 5 minutes, then it comes on again. I get the feeling this can be a bad sensor? Going up in elevation causing fluid to expand faster and hitting the sensor? Not too sure...
Opinions?
 
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your over heating your trans fluid. most likely going up hill. you need to take overdrive off and if you have to, manually shift it into 2nd. you need to be around 3000 plus rpms on long climbs to stay in your powerband otherwise your just slipping the torque converter too much.

says your all stock, but what size tires are you running. larger tires will put a huge load on your transmission temp on hill climbs.

if the light comes on again, just pull over and leave it at idle. the fluid needs to circulate to cool down and the light will turn off on its on
 
just changed the fluid 2 or so months ago. 31' tires. auto tranny... I guess staying in the lower gears is my best best then? I'll give it it try.
 
When your truck downshifts out of overdrive, your torque converter unlocks and starts slipping - that's what it's supposed to do, but it generates extra heat. Run like that too long at too high an RPM and you overheat the tranny fluid, shortening it's life and in the worst case shortening your transmission's life too. Like TT said, keep it below 3000 RPM and give it a break if the light comes on.

Try Purple Ice, I used it in my old automatic and never saw an AT temp light again.
 
I dont know the autos that well, but does it have a transmission cooler? If not It might be time to ad one. If it already has one, maybe a larger one is in order.
 
Unrelated problem but altitude related issue.

I've had similar problems with my '86, except it has a standard transmission. Here are some lessons I've learned that really helped.

1) These early efi computers could only compensate and change mixtures for roughly 1000 feet of elevation change. Read this somewhere (forum or sticker under hood).

2) If I stopped roughly every 1000 feet and reset the timing and idle speed, things got much better.

I figured this out because I make many trips from Texas to Colorado or other mountain states. The first few times by the time I was started getting close to the mountains my truck ran like crap. When I got in the mountains it got worse. I would spend the whole trip thinking something was wrong. Then miraculously half way home it would get peppy again and all was well.
 
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Set the timing with a timing light. Make sure to jumper the little plug.

Use the screw on the t-body to set the idle speed back to c. 700-750 rpm.
 
I don't mean back as in lower. I just mean back to specs. After dramatically changing altitudes it will be off higher or lower depending on if you go up or down. Modern cars correct for this. Our "classics" don't do as good of a job. It's not a huge deal, but every bit helps when you're trying to eek out as much power as you can from a 4 cylinder.
 
Hyde802 said:
I dont know the autos that well, but does it have a transmission cooler? If not It might be time to ad one. If it already has one, maybe a larger one is in order.
Click to expand...

the auto trans is plumbed to the radiator. the t case has its own cooler near the pass front frame area. since the fluid is shared, its like have two coolers. one air cool and another water cool
 
I want to add my .02 cents. This is exactly what my 1990 v6 4runner did shortly before my transmission went. What you are experiencing is significant slipping inside the transmission, causing the internal temperature to shoot up. The large incline is making it more noticeable simply because the gravity is making it MUCH harder for the transmission to convert engine power to the wheel.



I was able to limp on for several months by adding some transmission "additives" which really just different viscosity fluid that let the internal gearing "grip" better. She finally popped and I had it rebuilt.

It nothing, or very little to do with altitude. Transmission fluid is a hydraulic fluid that doesn't see significant change due to the small variation in altitude that your car is seeing. This is a temp issue caused by slippage inside the trans.
 
ToyoTech said:
the auto trans is plumbed to the radiator. the t case has its own cooler near the pass front frame area. since the fluid is shared, its like have two coolers. one air cool and another water cool
Click to expand...

between the t-case, and transmission?

no, I don't think they are shared. there should be a seal between the two. if they in fact ARE shared, that will be the first time ive heard of that.
 
nevada said:
between the t-case, and transmission?

no, I don't think they are shared. there should be a seal between the two. if they in fact ARE shared, that will be the first time ive heard of that.
Click to expand...

For the auto transmissions, the tranny and t-case do share fluid.
 
for the 3.0 auto. the fluid is shared. i think on the 3.4 they are not shared and the t case uses gear oil now instead of trans fluid
 
SV_Dude said:
22re auto shares fluid as well.
Click to expand...

kinda figure that too since it is the same trans i think. didnt wanna say since i wasnt sure. .

op. i would do a trans fluid exchange. stay in proper gear to be in vehicles powerband. i find mine around 3-4k 3500 is pretty good spot
 
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