Ok I read up on what a torque converter is and how it works. I now know more than 95% of automatic tranny owners in the world. That’s still not much though.

While towing, if I leave it in 3rd the tranny temps never go up. If I put it in overdrive as soon as the converter kicks in the temps start rising. I thought they would only rise from shifting but it almost seemed like they were rising while the converter was engaged. Does that make sense?

From what I read, I don’t really understand how the torque converter is ‘kicking in’ and giving me more power in overdrive. Can someone explain?

Also, I don’t think the converter ‘kicks in’ when in 3rd. Is this correct?

I’d like to know what the converter is doing to be able to better understand how its affecting temps. I’ve only ever owned manual trannys before so this automatic is still new to me. God what I wouldn’t give for the ability to shift only when ‘I want it to’ though…

 

From what i have heard, and i am not saying that i am psotive is that when you leave it in thirds in goes all the way in third, but when you shift into OD it has to "slip" a little much like a clutch would in order to shift smoothly into OD. But if there is not enough power or speed to allow OD to fully engage than it continues to "Slip" which creates heat, and cause the tranny fluid temps to rise. If you're pulling near the max then i would not use OD unless you are on a downhill grade.

As said above this is what i have heard and put together, not saying i'm positive.

 

Torque convertors generate more heat when they are unlocked, which can happen in any gear.

Waht you said does not make sense. What do you mean by torque converter "kicking in"? I understand the terminology lock and unlock for toraue converters, or engages/disengages. When you say kick in, does the engine speed go up or down? When you say "giving me more power in overdrive" I assume you mean the torque converter unlocks, engine speed rises by 200-500rpm, which goes along with my statement about causing more heat.

 

Yes to what you are saying. In 4th gear the rpms go up a bit giving you more power. Not third gear but simply fourth with the torque converter 'unlocked' as you're saying. I guess that's the lockup clutch dissengaging and the converter pumping fluid to give more power?

 

It's not that you are getting 'more power' when the TC unlocks, it's that the engine is now allowed to get into a slightly higher rpm (as much as 500 rpms) to get it into it' 'power band' and not 'bog' it with a locked TC...

It's doing the same thing that you are used to doing with the manual..... When you start to 'bog' in a higher gear, you manually down shift so your rpms pick up... You are not getting any additional 'power', just better gear reduction to move the mass you have at that given speed.

When the temp shoots up on the fluid in an automatic, it's during this unlocked time, and is the same as 'slipping the clutch' on a manual....

Mitch

 

Ok, so will running 4th with the torque converter clutch unlocked continue to elevate fluid temps or will it level off at some point? Aside from temps, will this prematurely wear out parts?

Reason I ask is it seemed I was getting better mpg in 4th with the converter unlocked than 3rd gear. Unf. the tranny temps started going up so I quit driving this way. I was thinking if I threw a fan operated cooler on there it might alleviate the temp increase. Maybe this just isn't a prefered way to run they tranny though.

Thoughts?

 

If the converter runs unlocked in 4th too much, turn off the OD and run it in 3rd. It should stay locked more in 3rd.

It wasn't that many years ago that all manufacturers with overdrive automatics specifically said NOT to tow in OD.