Tranny Cooler: Bypass or In-Series

[jgue467]

Are you running two external coolers?

Like:
Transmission —> first external cooler —> radiator —> second external cooler —> return to transmission

No - I didn't word that very well. I meant to say I tried running without being in series (not using radiator trans cooler - only external) and my temps would rise to 215 when towing. Once I put the radiator trans cooler back into series with the external it is able to maintain under 200 while towing in stop-go traffic.

I know not everyone needs this much trans cooling yet it is what works for my situation.

 

[cl4Rk]

No - I didn't word that very well. I meant to say I tried running without being in series (not using radiator trans cooler - only external) and my temps would rise to 215 when towing. Once I put the radiator trans cooler back into series with the external it is able to maintain under 200 while towing in stop-go traffic.

I know not everyone needs this much trans cooling yet it is what works for my situation.

And you’re running you external after radiator?

 

[Sarki]

Something to keep in mind for those who live in areas that have cold winters.
At 180K I replaced my radiator and added a B&M trans cooler which I installed in series with radiator trans cooler.
This is my DD, no towing or off-road use but it does see some heavy traffic during summer months where temps are 90-95 degrees.
Northeast location so winters are cold as in low teens or single digit.
Scangauge tells me trans temps during winter routinely stay between 95-120.
I don’t think this is an ideal situation as trans fluid never gets close to “normal operating temperature” regardless of how long my drive is.
How bad it is I don’t know, maybe someone can chime in and advise.
I do a partial trans fluid exchange every other oil change.

 

[Bad Luck]

Something to keep in mind for those who live in areas that have cold winters.
At 180K I replaced my radiator and added a B&M trans cooler which I installed in series with radiator trans cooler.
This is my DD, no towing or off-road use but it does see some heavy traffic during summer months where temps are 90-95 degrees.
Northeast location so winters are cold as in low teens or single digit.
Scangauge tells me trans temps during winter routinely stay between 95-120.
I don’t think this is an ideal situation as trans fluid never gets close to “normal operating temperature” regardless of how long my drive is.
How bad it is I don’t know, maybe someone can chime in and advise.
I do a partial trans fluid exchange every other oil change.

It's not ideal for transmission wear, but it's a lot better than running 210+. When I installed my external cooler I purposely chose a large cooler with a built in bypass valve. My temps stayed pretty cold during the winter as well even though I'm in the south because I completely bypassed the transmission cooler. If you are concerned about it then I would recommend plumbing back into the in radiator cooler after the external cooler (or switching from external cooler to radiator cooler) when it gets cold out. Also, keep in mind that the temps you are seeing on the scangauge (and ultragauge) will be the hottest the fluid possible. You're probably aware of this but wanted to point that out for anyone that comes across this in the future.

 

[Bad Luck]

My 01 schedule says coolant drain every 120 Months, I try to remember at 60.

The toyota red coolant does say good for 'Life' or 150K.

My factory maintenance schedule says to replace the engine coolant every 30,000 miles or 24 months. It repeats in the maintenance schedule every 30,000 miles as well.