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SOLVED: 4.0 Radiator swap...is this the one I need?


ecgreen

Well-Known Member
Joined
Sep 21, 2018
Messages
720
City
Dunbarton NH
Vehicle Year
1989
Engine
2.9 V6
Transmission
Manual
Total Lift
3"
Tire Size
33
Is this the correct radiator to do a 4.0 radiator swap into a 2.9 manual transmission BII?

 
If you are looking for more cooling, that looks like a single core versus the dual core that was in the 4.0 Explorers with A/C and automatic trans. It doesn't matter if yours is manual and you use the auto radiator. You just won't have any transmission lines connected to it. I got all my 4.0 radiators from the junkyard. Here's what it looks like from Autozone--notice the top view. https://www.autozone.com/cooling-he...iator/duralast-radiator-b2174/233600_107695_0
 
The one I got for my '87 2.9 is the CU1164, for a '94 4.0 auto Ranger. I had to use a 4.0 upper hose (21897) and cut it down so it would fit. Rock Auto is pretty good price-wise, though I'm not sure about shipping.
 
Very helpful thanks guys!
 
OK I swapped in the 4.0 radiator and here is how its running.

- IDles when warm around 180.
- Up hill it gets to 190-195 and I can see the temp drop.
- Every now and then at speed it will want to shoot above 200. I slow down or use the heater it drops again.

I am really not familiar with how things are supposed to perform. I am thinking it is still running hot.

Thoughts?
 
I believe some thermostats go up near 200
How do you get the temperature reading?
 
I believe some thermostats go up near 200
How do you get the temperature reading?

I installed an aftermarket gauge. After doing some reading, I am starting to think these temps are OK. More input appreciated.
 
You can test a thermometer by filling a glass with crushed ice, then add water to the top, then the thermometer should read exactly 32. I wonder if you could test the temperature gauge the same way, boil water and drop the sender in, it should read 212 in my figurin.
Just a FWIW :) haha, I don't really know if you really care, but I'm thinking I could use one of those myself
 
If you've got a 192-195° t-stat that sounds about right. Except with all the air flowing through the radiator at high speed the temp should come down (mine does, even with the AC on). Do you have an AC condenser in front of the radiator? If so, have you checked for bent/damaged fins, bugs, etc? When you say "at speed", do you mean highway driving at a steady speed?

If your temps get to around 190-195° and you can see the temp drop on the gauge, that tells me the t-stat is opening like it should.
 
Those temps sound about right. No matter how big the rad is the thermostat is going to limit flow through it to keep the block, where your temp sending unit is, at a stable temp between 195 and 200*.

The bigger rad just gives more surface area to help shed heat more efficiently in adverse conditions.
 
I developed an overheating problem in mine when I installed the dual electric pusher fans in combination with the single electric puller.

The issue came from the thermostat itself; too much airflow over the front of the thermostat housing will chill the thermostat off enough that it will not open. Toss a temporary heat shield in front of the thermostat housing and see what happens (cardboard works well).
 
So what is max temp? I read some threads that say up to 220 is ok.
 
218F is considered by most manufacturers to be where overheating begins.
 
2.9's are severely allergic to heat. Overheating (even once) runs the risk of blowing the heads off of 2.9/4.0 ohv engines. I have a 180 degree thermostat installed on mine for that exact reason.
 
So I should be shooting to not let it get over 200? Max 205?

Def gonna do the 180deg thermo
 

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