Frequently Asked Questions

Which is best for me, Hayden 678 or Hayden 698?

Hayden 698 has a built in thermostat which really only helps during cold engine starts below 30 degrees F since it helps warm up the ATF faster. Hayden 678 doesn't have the built in thermostat. Also if you plan on bypassing the factory cooler in the radiator I would go with the 698. Most of my orders are for the 698 by a small margin but you can't really go wrong with either.

Does the transmission cooler block air flow through the radiator?

No it doesn't. The bracket itself is skeletonized for optimal airflow and the cooler itself allows air to easily pass through. The large mechanical shrouded engine fan forces air through everything and I've never heard of air getting blocked by an aux trans cooler.

Does the transmission cooler "overcool" the transmission?

In my opinion as long as ATF temps are above 140 degrees F your fluid cannot be too cool. If this is a concern of yours, simply order the 698 kit with the built in thermostat.

Do I need an auxiliary fan?

In my opinion you don't need an aux electric fan if you are mounting the cooler in front of the mechanical engine fan. But an additional fan can help a little with slow trail speeds. I offer the fan kits as an option to purchase.

Should I bypass the factory transmission cooler?

Up to you. If you are using an older radiator and are afraid of the "pink milkshake" of coolant mixing with ATF then I would bypass the factory cooler. Otherwise generally I keep the factory cooler in the system and plumb the ATF from the factory cooler to the aux cooler.

How do the Hayden coolers compare to the factory coolers on my truck?

The factory in-radiator cooler is the diameter of your thumb and about 6 inches long. The Hayden coolers provide SIGNIFICANTLY better cooling than the stock in-radiator cooler (typically 20-30 degrees cooler).

My Tacoma or V8 4runner already has a small aux cooler with the tow package.

The Hayden coolers still provide a significant increase in cooling capacity due to their larger size and can still reduce temps by around 20 degrees F.

My dashboard "Transmission Temp" light has never came on, therefore I don't need this mod.

On all Toyotas the dashboard light comes on when the ATF is at 300 degrees F. By this time your transmission is actually already being permanently damaged.

FOR MORE INFORMATION AND INSTALL INSTRUCTIONS, CHECK OUT THE MANY YOUTUBE VIDEOS ON MY TRANSMISSION COOLERS