Added transmission cooler (I thought)

[Tyandkate]

I brought my truck in for a oil change and transmission service. While in I decided to have them add a external transmission cooler. So I got the call it was ready. The shop installed a NAPA rapid cool transmission cooler I’ll post a link to it at the bottom of the post here’s my concern.
The cooler was installed in the front of the radiator with a direct path of air. But they bypassed the transmission cooler built in to the radiator. Is this okay or is this going to be a issue while towing? Seeking advice from someone that has more knowledge on the subject. Thanks so much for the advice in advance.

The cooler is 11” wide by 9 1/2” tall 3/4” thick
https://www.napaonline.com/en/p/ATP17510

[1320Fastback]

Never bypass the stock radiator cooler. Transmission fluid that is too cold is just as bad as overheated fluid, normal engine temperature is ideal for the transmission fluid.

[MitchF150]

Even my 97 F150 came with a factory cooler and was plumped thru the rad first, then to the external cooler then to the trans.

It was even thermostatically controlled if I recall? (it was the E4OD)

I did add an aftermarket trans temp gauge to the line before it entered the rad.

This gave me the hottest temp the fluid was at before any coolers and it would never show over 100* until it got to around 175* I think.. Then the gauge would show it's actual temp.

Anyway, don't know what to tell ya, other than it's plumbed the way it is now, so until you get a gauge to tell ya, it's anyone's guess..

Mitch

[Tyandkate]

MitchF150- my trucks not new it’s a 2001 silverado. I was told the fluid looked a little dark giving the idea maybe the transmission was getting a little warm? That’s what made me decide to do a external cooler. I’m looking in to adding a temp gauge for it now. I’m told it does have a sensor to alert if the transmission is getting too warm but I’ve never seen it come on.

[MitchF150]

It's really a matter of 'opinion' really.. Some swear by the OEM setup and some swear by bypassing the rad altogether.. 😉

Kinda like do you run your RV fridge on propane while traveling or not.. ha, ha...

Most modern vehicle trans now have a thermostat that controls the flow of the fluid to the cooler, so until it reaches around 190*, nothing is going to the cooler anyway..

In my truck, it'll run 190* when it's 8* outside, or if it's 80* outside.. Does not matter.. It'll run hotter when worked hard in the summer, but that's to be expected too.

Anyway, unless you have a trans temp gauge, either from the computer or an actual mechanical gauge, you'll never know anyway, so what are you doing to monitor the temp in the first place?

Mitch

[mooky_stinks]

It should be thru the radiator and then thru the external cooler. That's how it's done from the factory. I've had stock trucks that run 120-140* in cold temps. From my experience, people that say the transmission will/can run too cold either don't know of or have never lived in cold climates where completely stock vehicles run at these temps.

[Tyandkate]

Also to add to the topic this is my mechanics reply to the question as of why the other was bypassed “having two coolers will cause the transmission to operate too cold therefore increasing the odds of transmission wear.”

[DownTheAvenue]

The hot fluid should go to the external after market cooler first, and then to the factory cooler built into the radiator. That way the fluid will be kept at a desirable temperature. The way it is plumbed now, the fluid cold stay way too cold, especially during cold ambient temperatures not towing.

[Tyandkate]

MitchF150 wrote:
Vehicles with OEM trans coolers always have it plumbed thru the rad first, then to the external cooler...

I'll go with how mine came from the factory.. 🙂

Good luck!

Mitch

It was my understanding it was going to go in the radiator out then external cooler then back to the transmission.

[MitchF150]

Vehicles with OEM trans coolers always have it plumbed thru the rad first, then to the external cooler...

I'll go with how mine came from the factory.. 🙂

Good luck!

Mitch