Big block 727 3k stall Transmission overheats

[Mrs. 69 Bird]

I am having a over heating issue with my big block 727 Transmission with 3k stall converter, I have a trans cooler with a fan pushing through it but after maybe 15-20 miles of driving, it would get upto 210 degrees, I evened bypassed the thermostat to straight 12 ignition switch for the fan but will still overheat over time.. Any ideas on how fix it?? Or should I

switch to a Tremek 6 speed manual transmission? Any information will be a helpful..

 

[bm02tj]

At a slow cruise gear down so converter is not slipping that is where the heat comes from
After trial and error you will find what gear to select

 

[pnora]

What radiator? Do you have a shroud? What type of fan? What is your ignition timing?

 

[ruffcut]

Lots of unknown variables like @pnora was asking.

 

[pnora]

One item jumped out at me on your engine picture. Pulley size. That crank pulley is small and the water pump is large. That tells me you may not be spinning the water pump fast enough.

 

[A70Runner]

I may be wrong but I think they are talking about the trans overheating, not the engine .

 

[F4R/T]

Your combo sounds off, what gear ratio are running because you need to get the engine out of the stall range of the convertor . Pulley size is critical and fan size and set up, radiator . Share some more information on your combo.. cam compression etc.

 

[1 Wild R/T]

As others have mentioned... Please clarify, engine temp or trans temp... My take is your concerned about trans temp... So gear ratio becomes a serious question... A 3K stall convertor, especially one of the budget minded variety needs to live at of above it's rated stall... So if your running 3.23's and what looks like a pretty tall tire at 65 MPH your spinning the engine at around 2500 RPM's and the convertor is slipping creating heat... You either need to drive faster, change to a numerically higher gear or run a shorter tire.. Or swap convertors... Either a lower stall, or a tight 3K unit...

Assuming a 28.5" tire & 3.23 gears 80 MPH is 3000 RPM's...

 

[#41]

Not too many people run a trans temp gauge. IMO, it does not need fixing. 210 is not excessive for a 727 with a 3000 stall in a warm climate.

 

[sabre67]

 

[493 Mike]

210* is not even hot enough to boil water. Just like engine oil, transmission oil has to boil off any moisture from condensation.
Mike

Mechanic Base
https://mechanicbase.com/transmission/normal...

What Transmission Temperature Is Considered Normal?​

Most modern automatic transmissions are meant to operate at temperatures between 175 and 225 degrees Fahrenheit. If it gets any hotter than this, there’s a mechanical problem that should be dealt with.

 

[DanielSlocum]

Headers? If so, are your trans coolant lines insulated from header heat?

 

[1 Wild R/T]

210* is not even hot enough to boil water. Just like engine oil, transmission oil has to boil off any moisture from condensation.
Mike
View attachment 1685844
Mechanic Base
https://mechanicbase.com/transmission/normal...

What Transmission Temperature Is Considered Normal?​

Most modern automatic transmissions are meant to operate at temperatures between 175 and 225 degrees Fahrenheit. If it gets any hotter than this, there’s a mechanical problem that should be dealt with.

I agree to a point.... 225 may be normal for newer vehicles running synthetic fluid but conventional fluid like most of our cars run starts breaking down around 200 degrees... I wouldn't be to concerned about 210 but if the temp continues to climb then it does become a serious concern... Luckily Florida doesn't have much in the way of mountains and I doubt that Roadrunner is gonna be towing any trailers...

 

[493 Mike]

I agree to a point.... 225 may be normal for newer vehicles running synthetic fluid but conventional fluid like most of our cars run starts breaking down around 200 degrees... I wouldn't be to concerned about 210 but if the temp continues to climb then it does become a serious concern... Luckily Florida doesn't have much in the way of mountains and I doubt that Roadrunner is gonna be towing any trailers...

I have switched to ATF+4 in all my TFs. After reading comparison specs I see no reason to use Dexron.
Mike

 

[Phantomx]

Agree with some above. If you’re cruising around with the rpm below the stall speed of the converter, it’s going to be making big heat because the converter is slipping like mad. It’s not a modern unit with converter lockup, so you need your cruise rpm to be above the stall rpm to keep it happy. You either need a tighter or more efficient converter, a smaller cam so you can use said tighter converter, or lower gears to make your cruise rpm higher (or just drive around in second gear). Or my personal favorite way of curing the suto trans blues, install a manual.
Travis..

 

[ruffcut]

Yea, I thought a tighter unit also would cure the overheating.