What would make my 4L65 run hot? 225*

[K85 Octane]

So in my '68 lies an LS/4L65e. I had the cooling lines running into the radiator for the trans. It would see 220, 13 miles of stop and go traffic, by the time I get home from work. At times, even using the freeway, it would see these temps and occasionally hitting 225-228*.

I checked flow through the lines and that seemed fine. Plus, when I took the lines off everything was full of fluid.

So now I have about 30" of heat sink along my frame rail with the cooling line ONLY going to it. It doesn't heat up as fast but it is still seeing over 200*. The test run (and only run so far) saw 208* doing nothing but driving. (no pulling a grade, no constant racing at every light, etc) I felt the lines and they were hot and pulsing, plus the fins were hot, so it seems I have flow.

I don't know. This ain't right. By comparison, my "old" 700r4 takes a beating in the blazer all BB long and doesn't see over 190, with the majority at 180. WTF?

I guess I need to have the program checked.
BTW, the lockup IS working.
Whatcha think?

 

[K30Blazer]

More cooling. I had to put an extra cooler on mine. I saw the same temps you did but with an additional cooler I am now running back at 180 while towing

 

[sweetk30]

ls engines run hotter than older engines = more transferred heat

 

[Greg Ducato]

The lockup on the 4L60E is PWM style and thus can generate heat even when partially locked. In town and other driving on and off throttle does not produce 100 percent lockup. I would like to see temps below 190 in normal driving but 200-210 is not unusual for hot climate stop and go. I agree and extra cooler will be in order plumbed between the return line and trans.

 

[K30Blazer]

I have a derale puller fan cooler setup. Fluid goes from trans to radiator to derale. Fans come on on cooler at 180. Before I was just using the derale I would constantly see 230 to 250 especially when towing.

This pic was taken pulling my trailer up a pretty good grade by me on a hot day. Two shots. First one is temp sensor in the body and second is temp sensor in the pan


I can now see the difference the cooler is making as I can watch the hotter temp drop.

This is about as hot as it gets and this was me hammering it.

I was amazed I needed more cooking but haven't had an issue since. I also switched to amsoil fluid fwiw.

 

[Babaganoosh]

Brent,where do you have your gauge sender or are you picking it up from the ecm?

 

[K85 Octane]

ECM
And you guys are talking about towing conditions and such. This is just daily driving a vehicle with a lighter GVW than what the drivetrain originally came in.

So a 2005 suburban, in stock form, sees 220+° all its life? I can't image what it sees during factory recommened towing ability lol The truck definitely shifts different when its above 200

 

[skunked]

So a 2005 suburban, in stock form, sees 220+° all its life?

No it doesn't.

 

[Greg Ducato]

That is rather warm for normal operation, I'm guessing you have some issues in the TCC system not allowing full lockup. Notice any extra firm 1-2 shifts especially coming off a long highway drive?

 

[Greg Ducato]

stock stall speed converter from a truck application?

 

[79rustyk10]

I was under my 06 silverado 1500 after a 40 mile drive home, some stop and go. the pan was cool enough to touch. I do have the aux trans cooler, and its also 50 degrees out here too.

Wish i could help more.

 

[Joe In Montana]

It would see 220, 13 miles of stop and go traffic, by the time I get home from work. At times, even using the freeway, it would see these temps and occasionally hitting 225-228*.

Getting hot in stop-and-go?

Fan clutch.

 

[K85 Octane]

stock stall speed converter from a truck application?

Stock converter

That is rather warm for normal operation, I'm guessing you have some issues in the TCC system not allowing full lockup. Notice any extra firm 1-2 shifts especially coming off a long highway drive?

The trans has a vette servo and 1-2 accumulator spring (I think, that's what I asked for, which is the same as my S10 and was great)
Actually, I have noticed that every time I slow down I can feel it down shift. As in, each time I come to a light or stop sign I can feel 3rd... 2nd....1st as I come to a stop.
Hmmm, ok now that I said something I'm curious...

 

[Greg Ducato]

You will feel downshifts if it is in third (drive), not so much when the selector is in overdrive,it changes the path of the oil. If you feels all these in overdrive the converter clutch may be staying on too long or the servo piston is bottoming out against the cover.

 

[wetoolowdingbangow]

Hmm.

I suspect the problem is it being an automatic.

Haha! Sounds like a bigger cooler is in order. They say the running range of those 4l65s is 170-200.

I suppose throwing another cooler inline is a good first stab.

 

[K85 Octane]

You will feel downshifts if it is in third (drive), not so much when the selector is in overdrive,it changes the path of the oil. If you feels all these in overdrive the converter clutch may be staying on too long or the servo piston is bottoming out against the cover.

I will take that up with the guy who builds my transmissions locally. Appreciate it Greg, always