97 Radiator in an 87

[Bubs2.0]

I've got a 1987 Ranger with a 4.0, MT and axles swapped in from a 1994. The single thin core radiator from the truck was working ok, but recently, on +75 degree days, the engine's getting a bit hot.
I have a mechanical temp gauge and it's been showing (if it can be believed lol) a little under 210F when cruising down the highway at 75 mph.
When I slow down, the temp drops down to 205F ish and when I put the heat on full blast, temps go down to 190F-200F.
I chopped of the mechanical fan and have a stupid underpowered electric fan zip tied to the rad (was young and dumb when I did that) but it's seems to keep temps under control at low speed.
Seeing how effective it is to turn the heater on full blast leads me to be suspect the radiator is junk.

My plan is to upgrade the radiator to a thicker one and install a proper electric fan with a functional shroud.

Questions:
Is the mechanical fan effective to keep temps down at high speed and high ambient temperature?
I need to fix the electric fan, but I don't think it's causing my temps to be high at highway speeds.
My thought is that at 75 mph, more air is getting pushed through the radiator by the truck plowing through the air than what a fan can pull, so a stock mechanical fan or crappy electric fan isn't going to make a difference.
Might be wrong here, maybe that stock fan pulls a crap ton of air.

Has anyone swapped a 95-97 radiator in a first gen truck?
I picked up a 97 4.0 AT radiator (super cooling 2in core) and it's taller than the stock 94 radiator.
The top mounts look the same and it looks pretty straight forward to chop off the original bottom mounts and fab up some mounts to mount the 97 radiator.
I'm just wondering of someone has done this before or if I should just try find a 91-94 4.0 AT radiator.

Pic of the truck, it gets 20 mpg doing 75 mph!

 

[superj]

welcome to the site!!


the fan actually only works at under about 30mph in a vehicle cooling system. above 30mph the air flowing through from driving does the cooling.

since you are staying cool enough below 30, your electric fan is probably also good enough to not worry about going back to a mechanical fan but, mechanical fans work great and until more recently, were the way of hte world so you know they work. since you are already set up for the electric, i would keep it until after the new radiator and if it works, stay with it since it is more efficient, gas mileage wise.

the reason you are heating up is your radiator needs replacing. heating up while idling or slow moving is the fan clutch and heating up while driving is the radiator. those are generally the rules for heating issues in a vehicle.

you can replace your factory unit with another factory unit and be fine, or upgrade to a two core larger and be fine. i generally like to go with a larger radiator if i can fit one in without to much work because it allows more coolant to carry away heat.

 

[scotts90ranger]

Personally I prefer the earlier mounting method but since you have the radiator you're right, it wouldn't be too bad to make the little saddles the newer style radiator needs, make sure to put in a rubber buffer in there, my '00 Explorer was missing that and it sat crooked and ended up breaking the radiator and condenser...