Can a transmission oil cooler be TOO big?

I have a stock, 2wd Tacoma and I don't tow anything currently, but I likely will in the future (small aluminum boat, etc.). In the interim and like all of us, I just want my transmission to last as long as possible even though it's my daily driver!

Having said all of this, I was reading on another forum about the

$51 Hayden 678 Universal Rapid-Cool 9.5” x 11” Add-On Transmission Cooler – Not for Direct Replacement of the OE Cooler

Hayden 678 and 679 coolers and the poster was concerned that while you want your fluid to be cooler...you don't want it to be TOO much cooler. He was wondering if, by installing a larger tranny cooler, you're doing your fluid a disservice by making it too cold!

Is this possible? Is there such a thing as keeping your tranny fluid TOO cool, or is this concern a bunch of hooey?



Ed

 

I cant imagine your oil would ever get any colder in California, regardless of cooler size, than those of us up north.

It isn't a bunch of "hooey" but we drive when it's well below freezing temperatures and dont have an issue.

 

You want it to get warm enough that it will shed any moisture/condensation that accumulates when your vehicle sits. Probably will never be a concern in most applications. I think I've seen more tow rigs on the side of the road from botched installs/poor quality tranny coolers than cooked transmissions.

 

Don't buy a Hayden. They don't have a bypass for cold starts. I bypassed my factory cooler with Tru Cool 4454. On hot days my temps are no higher than 180 with no load. I'll be courious this winter. I used to have a TRD (Hayden) in series of the radiator cooler. During the winter my temps barely saw 100 degrees.

 

Where did you mount the Tru-Cool unit? Any pics?

 

Ignore him. A transmission cooler doesnt make anything cold.

 

The TRD being a Hayden, were installed on thousands of trucks that drive in freezing winter temperatures much colder than texas without an issue.

 

Not really answering your question, but I have a Tru Cool 4490 out in my garage new in box if you want it. Just pay me 13.00 for shipping and you can have it.

 

Including mine, nothing wrong with Hayden....they don't have the internal bypass like tru cool or b&m. If you plan on bypassing the factory cool the bypass would be a must for cold starts.

 

I used this write up. Instead of spacers I used washers and bypassed the factory cooler. http://www.tacomaworld.com/forum/1st-gen-tacomas/108470-hayden-transmission-oil-cooler-install.html

 

That's a nice cooler.

 

Too big could be a concern if mounted in the front of the rad creating a loss of air flow to keep the engine cooled .
Years ago , GM released a TSB about overcooling the transmission in cold climates . Transmission fluid would actually turn to somewhat of a gel . Transmission fluid needs time to warm up in those climates that are 30 below and colder . I doubt the OP has anything to worry about as mentioned above .

 

Do the second gen Tacoma s have a thermostat in the lines. My Tundra has one.

Putting a bigger trans cooler in would require more fluid as well.

 

I was curious if you mounted on the passenger side and if you had to move the horn as zero4 did?

Thanks for the help.

 

Yes I moved the horn to the driver's side. I bought different length bolts and nuts, forgot the size. I installed the line coming out of the transmission to the top of the cooler, bottom of the cooler back to the transmission. Makes sure you get longer 3/8 oil line.

 

All great info. Thanks man.