4L80e cooling issues - am I insane or something going on with it?

[big-blue]

I went ahead and ordered a new pigtail for the pressure side of the switch and RockAuto had a closeout deal for an ACDelco switch for $3.50 ... so I couldn't pass that up. Might as well put a new switch in there since I have no idea was it was disconnected in the first place.

However, I went ahead and put a toggle switch on that wire - as I wanted to really determine if the TC lockup would work. So, just after going into 4th, I turned the switch on. About 60MPH and 2000RPMs, it locked ... and the RPMS dropped to about 1800 and the truck wanted to go! ;-)

So it seems that the TC can lock now - yay! Is the line of thinking now that if I am towing, and it's locked ... and it stays locked (i.e. not hunting back and forth), that the trans temps will be lower, than not having it locked up?

I don't want to assume anything here, as I want to have the computer do it's thing but I want to make sure with regards to the towing aspect to all this.

Thanks again!!!

 

[Greg Ducato]

It is ok to tow up the the vehicles factory rating in overdrive. The computer is designed to lock and unlock the converter according to throttle position and speed. I would let it do it's thing, the 4L80E has an exceptional clutch and damper, the largest of its time until the Allison

 

[Greg Ducato]

And congratulations on your diagnosis and repair, job well done

 

[big-blue]

And congratulations on your diagnosis and repair, job well done

Thanks Greg. It's been over a year now that I have been dealing with it - where I should have just addressed the cause opposed to just adding attacking the symptoms.

I know every climate is different, but I should be able to plumb this back to the radiator with one of the aux heavy-duty coolers afterwards and be around 180F +/- 5F, when towing? I am not too worried about it now ... but come June ;-)

Thanks again!

 

[Greg Ducato]

It would not be unusual to see towing temps nudge over 200 degrees depending on load and terrain, but unloaded you should see at least 20 degrees less on the highway with the converter locking

 

[big-blue]

It would not be unusual to see towing temps nudge over 200 degrees depending on load and terrain, but unloaded you should see at least 20 degrees less on the highway with the converter locking

Understood and thanks again for the replies. Much appreciated sir!

 

[Blue85]

if I am towing, and it's locked ... and it stays locked (i.e. not hunting back and forth), that the trans temps will be lower, than not having it locked up?

Yes, the temps will be much lower. The slip in the torque converter is probably the biggest continuous heat source in the transmission. You will also appreciate the fuel savings.

 

[big-blue]

Yes, the temps will be much lower. The slip in the torque converter is probably the biggest continuous heat source in the transmission. You will also appreciate the fuel savings.

Thanks!

 

[4X4HIGH]

Just for reference, my trans runs right about 170* (my trans is a 700R4 but like I said as a reference) whether stop and go or cruising, if I pull a hill it will climb to around 190*-200* then back to 170* when leveled out or if towing the same thing when pulling a hill. My gauge is an Autometer Sport Comp and is a mechanical gauge plumbed into the pan as well. I also run a mechanical Autometer engine oil gauge and it runs right at the same temp as the trans and mirrors the rise in temps.

 

[big-blue]

Just for reference, my trans runs right about 170* (my trans is a 700R4 but like I said as a reference) whether stop and go or cruising, if I pull a hill it will climb to around 190*-200* then back to 170* when leveled out or if towing the same thing when pulling a hill. My gauge is an Autometer Sport Comp and is a mechanical gauge plumbed into the pan as well. I also run a mechanical Autometer engine oil gauge and it runs right at the same temp as the trans and mirrors the rise in temps.

Sorry for the late reply. Thank you for the reference point 4X4HIGH. I still have my TC lockup on a toggle switch; I received the new brake switch, but apparently pigtail is still on its way ...