davis4004

What is the size of the stock transmission cooler in a 1991 Max? I'm wondering because I am going to bypass the stock cooler to prevent the old debris from getting into the the new transmission and I want to get a cooler that is big enough to make up for the the old cooler. Thanks!

Chris91SE

iTrader: (1)

there is no external tranny fluid cooler..if you have a new tranny put in...put in an external cooler (check sticky up top) and most likely new fluid would be put in anyway during the swap

brubenstein

There are tubes in the bottom of the radiator for the ATF to flow through. This is done for two reasons: get the ATF up to its operating temp, and keep it from getting too hot. The transmission will not go into OD until the fluid temp goes above ~125F. It is only a so-so cooler. In summer time, bumper-to-bumper traffic the coolant gets fery hot, and even though the ATF goes through the cool part of the radiator it won't cool it much at all. If you bypass the radiator ATF coil it will take longer for the ATF to come up to temp. I suggest using synthetic ATF if you live where the temp goes below freezing, since it won't thicken up as much in low temps. The B&M 70255 cooler is a good size. Any bigger and the ATF will take a very long time to come up to proper operating temp.

Mizeree_X

iTrader: (9)

I was wondering about this, because its been asked a few times. Why not just replace the radiator when you replace the transmission. Considering it is a fraction of the cost of a new transmission, it seems like a good idea to me. My $0.02.

brubenstein

According to the Nissan TSB's, if the tranny frags itself, there is a lot of junk in the ATF or the cooler is suspected of being blocked the radiator should be bypassed or replaced.

davis4004

I ran some fresh oil through the lines today with and it seemed to be fine, the pressure going in and coming out were the same and the fluid came ouit clean so I don't I'm going to bypass it, unless it is going to reclog itself easily.