The stock radiator is in pristine condition inside. I'm religious about cooling system flushes. So, I know it's not corroded or blocked. I pulled the radiator a while ago and pressure washed the core. That helped. It took quite a while to get all the red Moab dirt out. I checked when we were swapping the engine and it's still nice and clean so that's not the problem now.

The stock Sport radiator is different than the Montero radiator. Only one row. Checked and the 3.5L and 3.0L are the same so that rules out changing to the 3.5L Sport radiator.

Based on what I can see - heating up on long assents at low speed and assent on the highway it appears that there's either not enough coolant volume being pumped through the system and/or the radiator just doesn't have enough surface area. The ARB bull bar blocks a lot of air flow on the highway.

I run the Ford Contour dual fans.



These fans move a LOT of air. It'll cool down 10 degrees in less than 30 seconds once the load is off even in 100 degree weather. As you pointed out, no fan will work if the radiator isn't big enough.

I've been talking to tech at Spal and their opinion is this: For crawling - the radiator just isn't big enough - especially with ambient temperatures pushing 85-90+. Hauling 5500 lbs up a steep incline at 3K RPM produces a lot of heat, there's zero air flow from movement and the radiator is just too small.

On the highway he thinks a good part is that there's too much stuff in front of the radiator blocking the air flow I'd normally get from driving. He suggested removing as much stuff from in front of the radiator as possible and go from there. He still thinks the radiator is too small, though.

He strongly suggested addressing the radiator first for both problems. Anyway, that's pretty much what everyone I've talked to says and it's what I've more or less deduced for my self.

Right now I'm looking at going with Griffin. 3.25" core - dual tube. Any input on alternatives/someone better would be welcome.

Edward