2 Issues I'm Looking for Help Diagnosing...A/T Oil Temp Light & New Power Steering Pump (1 Viewer)

Joined
Jan 4, 2015
Messages
203
Location
Tucson, AZ
First Issue: A/T Temp Oil Light...

Background...I drove in 2H on the beach & the A/T Temp sensor came on, followed by a fire where there was a slight amount of transmission fluid coming out which caught fire. I had a shop in the Seattle area drop the transmission pan, replace the filter & do a fluid flush.

Now, on a couple of easyish trails, the A/T Temp light has come on a couple of times.

Could I have damaged something in the transmission which is now causing the transmission fluid to run hot by driving in 2H on the beach, or did the shop screw something up?

Second Issue: The same shop I had do the fluid flush, I also had replace the power steering pump. It worked for a couple days, and then, power steering went out again. A week later, again. and now, a month later, struggling again. Twice, I took it back to that shop, and they claimed that a new power steering pump for an 80 is just difficult to get all the air out. Twice, they both lifted the vehicle up in the front and turned wheels side to side, as well as leaving it on the ground turning side to side. It seemed to clear it up short term, but it's repetitive. Any advice to get the new power steering up to function properly?

TIA for any tips/guidance!
 
Joined
Mar 30, 2009
Messages
770
Location
Indiana
From a 2009 post:

Your 'A/T Oil Temp' light comes on at 305º and goes off at around 120º, IIRC.

From the way you describe it sounds like while in 3rd gear the overdrive direct clutch is slipping which is causing the heat (if you're not in lockup.) Remember, the Torque Converter is multiplying the torque from the engine rotation, so if the lockup is not engaging then you could be heating up those clutches.


How does the fluid smell? And where was the transmission fluid coming out? Does it shift normally?

On the power steering pump, you can bleed it yourself. Get the front end in the air on jack stands or blocks where the wheels can turn freely. Turn from lock to lock, with the truck running and the cap off. Add fluid until it's at the correct level. Can take several attempts to get all the air out or could take minutes.
 

cvenom96

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Sep 14, 2015
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302
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Frederick, MD
On the p/s pump, I had trouble getting mine bled until I revved it to about 2k and then turned lock to lock. Seemed to do the trick.
 
Joined
Jan 4, 2015
Messages
203
Location
Tucson, AZ
From a 2009 post:

Your 'A/T Oil Temp' light comes on at 305º and goes off at around 120º, IIRC.

From the way you describe it sounds like while in 3rd gear the overdrive direct clutch is slipping which is causing the heat (if you're not in lockup.) Remember, the Torque Converter is multiplying the torque from the engine rotation, so if the lockup is not engaging then you could be heating up those clutches.


How does the fluid smell? And where was the transmission fluid coming out? Does it shift normally?

On the power steering pump, you can bleed it yourself. Get the front end in the air on jack stands or blocks where the wheels can turn freely. Turn from lock to lock, with the truck running and the cap off. Add fluid until it's at the correct level. Can take several attempts to get all the air out or could take minutes.

Thank you so much. I've dove into and learned much about this truck over the years, but I know nothing with respect to gears/clutches/etc. If you were dealing with this situation, not having the knowledge of repairing on your own, what would you do? Speaking mostly to the transmission stuff. Should I be looking to source full system parts, or is the diagnosis & repair path not a total pain in the arse? I'm thinking I'd rather pay for ease or upgrade vs. repair, especially self repair at this time.
 
Joined
Jan 4, 2015
Messages
203
Location
Tucson, AZ
From a 2009 post:

Your 'A/T Oil Temp' light comes on at 305º and goes off at around 120º, IIRC.

From the way you describe it sounds like while in 3rd gear the overdrive direct clutch is slipping which is causing the heat (if you're not in lockup.) Remember, the Torque Converter is multiplying the torque from the engine rotation, so if the lockup is not engaging then you could be heating up those clutches.


How does the fluid smell? And where was the transmission fluid coming out? Does it shift normally?

On the power steering pump, you can bleed it yourself. Get the front end in the air on jack stands or blocks where the wheels can turn freely. Turn from lock to lock, with the truck running and the cap off. Add fluid until it's at the correct level. Can take several attempts to get all the air out or could take minutes.

Also, quick thought from your notes, I do have a center diff lock switch. The light comes on that it's engaged. I often times on dirt roads or beach leave it locked in 4H. Could this be a system/part of the issue...related to the clutch/etc. you spoke of?
 
Joined
Jul 17, 2018
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1,142
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KN4YJE LUGOFF, SC
No, the diff lock is used to tie the front and rear drive shafts together to split torque 50/50 to the front and rear end, you are using it properly on soft surfaces.

The Torque Converter lock up has nothing to do with the transfer case where the center diff lock is located.

The torque converter is a large radial pump. I am going to radically simplify its function to attempt to explain how it works. It looks like a pair of fans, one fan drives the other. (Go ahead and set up of a pair of fans in your living room to see the effect) When the moving side fan (engine side) pushes trans-fluid into the static side fan (transmission with vehicle stopped) force is applied. As engine RPM is increase the force applied becomes large enough to move the vehicle. As you can imagine there is slippage, after-all its two fans that are not traveling at exactly the same RPM, the driven fan lags behind. When it lags it creates heat in the fluid.
To minimize the heat build up, there is a clutch that engages and couples (locks) the driven fan to the driving fan as the driven fan approaches the speed of the driving fan. It disengages when you slow down to stop so that the torque converter fans can have slippage so the vehicle can stop.

If this clutch that is supposed to lock the two fans together doesn't lock up, there will be excess heat created in the shearing of the fluid. It is non serviceable other than to change the torque converter.

Here is an excellent article on the subject.

This lock up only occures above a cirtain speed, I will need to consult my FSM for the information, but my guess is you never got moving fast enough to engage the torque converter lock. Hence the high transmission temp.
 
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