I’ve been going crazy trying to figure this one out. I have a 99 Maxima SE with 138K miles on it manufactured in 11/98. The radiator finally started cracking so it’s time for a new one. The Nissan dealership does have them anymore that they can order so it is aftermarket at this point.

I have not been able to get a straight answer but each aftermarket radiator has slight differences where the automatic transmission oil lines are located. Since I don’t want to stretch the new hoses to a different location I figure I would stick with the ones with the right locations.

The difference now if I stick to the right hose locations is the core size (thickness). Everything points to my 99 as if it should have 26mm core from RockAuto to Radiators.com, but when I measured my radiator it is 16mm. The Nissan started using 16mm in the 2000 model (I assume to save money) but somehow I got that installed on mine (I brought the Maxima new with no radiator changes). Looking at some part history is looks like the 26mm core was made up to July 1999 and the 16mm started manufacturing in April of 1999.

I like to stick with original specs but I may not have a choice. The 16mm should be the right size for 190 HP.

Do any 99 owners have 16mm or 26mm? If I just upsize to 26mm (a difference of .375“) does that matter for cooling. I’ve had cooler issues in the past so I’m ultra sensitive and never had to change thicknesses.

And yes I’m a mechanic that’s also an engineer so I’m overthinking this.

 

My 99 is thin. My old 98 was thick. I don't think it matters.

 

mishimoto makes an all aluminum one that is bigger as well. i thought it cooled better on my 99. if you are sticking to oem, i know denso makes one for our cars and that is oem on a lot of cars. nissan typically uses calsonic though.

 

The all aluminum Mishimoto is for 5 speed MTs only. It doesn't have the section to cool ATs. One would have to find another way to cool the transmission fluid.

I'm most likely going to buy the Klimoto radiator on Amazon for my 1999 SE.