Ye Ol' Cherokee

Please give your input on this if you have any

Okay so i installed a Hayden Transmission cooler a few months ago, and lo and behold, it's leaking somewhere out of the tubes. I'm not sure if it's cracked, or whats going on, but i'm not worried about it because they are covering a replacement. (I am not driving it for now)

This got me thinking though. I have been hearing issues with failing aux transmission coolers causing coolant to mix in the transmission causing failure... So if the Aux transmission cooler fails, how would that happen? The fluid is coming from the transmission, to the radiator, then to the aux cooler, then back to the transmission nice and cool. So when it is passing through the aux cooler, it already left the radiator, so how would it mix?

My assumption is that this happens when the radiators internal transmission cooler fails... and if that is the case, couldn't this happen without even having a aux cooler installed?

Jeepin'Hubb's

I don't see how an aux cooler failing could result in mixing of coolant. I could see the mounting of the aux cooler by use of those zip tie things to cause the cooler in the radiator or the radiator itself to fail allow for mixing at the radiator. I could be way off tho just my opinion.

Roler

You're correct, aux cooler failure can't mix with coolant. Rad ATF cooling section could fail but section is separate from coolant section for that reason.

SteveMongr

The Hayden cooler is 'tube & fin' type and the tubes are thin wall copper.
A better design is 'plate & fin' made by B&M Coolers. These do not flow fluid through a tube, they circulate fluid, have a larger capacity for the size and are more efficient. Also durable, unlikely to break or leak.
These also can be used without the stock cooler because they restrict flow when cool to allow the tranny to warm up. This is part of the reason the stock cooler runs through the radiator, to help bring the tranny up to operating temps. I understand the AW4 operating temp 150F - 160.

dmill89

Hayden makes both tube & fin and plate & fin coolers (I generally prefer B&M, but Hayden plate & fin coolers aren't bad either). Obviously the plate & fin coolers are more expensive and Hayden also make several "grades" of tube and fin coolers. Their cheapest tube & fin coolers (the ones you usually see in auto-parts stores) have just about paper-thin tubes which are very easy to damage.

RTorrez1

The only way that the trans fluid would mix with the coolant is if you are still using the radiator trans cooler. But if you eliminate it from the trans and only use an external cooler there is no way for them to mix.

SteveMongr

Thank you for clarifying.
Now knowing there are different grades, it makes sense to get a the heavy one because of the vulnerable location.

Ye Ol' Cherokee

This is what i REALLY wanted to do, because this is exactly what i was thinking.

i have a major issue with it though. I live in Philadelphia PA, and our temps range from up to 100 in the summer and down to 0 in the winter, so it would be fine for spring/summer/fall, but when winter hits, the temperatures are typically 20-30, sometimes dropping into the single digits, and i feel that this would cause the transmission not to warm up in the cold mornings.

My trans is in good condition, i don't want to kill it running it while its too cold... What do you guys think about this dillemma?

djb383

I have never heard of tranny damage due to cold. B&M recommends installing the auxiliary cooler inline with and after the OE factory cooler. If u eliminate the OE cooler, it would be a good idea to also have a fluid temp gauge.

Strmtrooper70

I've eliminated the cooler off a radiator and only used a auxiliary cooler and never had any problems in a car with 420 horsepower and 450 ft lbs of torque. the transmission temp always reads 100 and 150-160 in traffic I had a tube and fin design but they are too fragile i found a nice plate type off a Ford explorer they are strong and work very well and they are at every junkyard. I would recommend a fan to it too just because when you're wheeling you're not doing 50 plus mph to keep air flow moving through it.