1975 FJ40 440 Swapped

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LucasF

LucasF

Joined
Apr 1, 2024
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Location
Los Gatos CA
Bought a 75' FJ40 about 6 years ago with a 440 stuffed under the hood. It was a DIY project and the guy never got around to driving it so he never had the cooling really figured out. Been trying to figure out cooling ever since but haven't quite got it down yet. The problem is the limited space for airflow and the lack of size in radiator that you can fit. Just posting this on here to see if anyone knows how to combat this issue or has any experience with something like this. On a nice day, about 65 degrees, idling in park, the temp tends to sit around 190-200. Goes down a little while driving on a downhill or off the throttle, but when on the throttle+ going uphill the temp starts to climb 210+.
 
Maybe there is a really good many core aluminum radiator that will fit with a big electric fan. Isn't there like some special additive/stuff that has better heat exchange than water antifreeze. Enlarge the hood vents to let out more heat. Put an air scoop on the bottom to push more air out the hood vents.

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Thanks for the advice, will look into a new radiator and better airflow for hood vents as well as that special additive. Do you by chance know what the additive is called?
 
Many swaps lose the fan shroud. You must have a well-made, close-fitting fan shroud so that the engine fan does some good.
 
Are you using stock radiator ? does it have a shroud ? are you running mech fan or elec ? FWIW thos temps are not bad, thats where my lq9 6.0 ls runs with stock radiator and mech fan. I would look at venting the engine bay, louvers in hood or delete inner fender as well if it stays too hot but again, those temps are not all that alarming. and the fact it pulls the temp down means its working and some adjustments might work, better fluid, shroud, good thermostat, good water pump ( high volume). Actually for a 440 I am suprised it runs that cool.
 
If you ever plan to run any trails that are slow and idling in a group a huge electric fan for the radiator would be a must. Even then it still going to be on the hot side.

The cab is going to require tons of insulation if running a hard top. Only factory insulation was areas the exhaust was close to cab. Heat in the engine bay Toyota really didn't plan for. The 75/76 models were the worse years for interior heat. 74 was the last year for the vent window in the side doors in the US market. 77 model was first time since the vent was removed in the cap some time in 1963 there was a way to flow air out of the back.
 
Radiator is not stock but is at least 8 years old. Dual electric fans that are fairly new. Most of the inner fender is cut away and there are pretty large hood vents. The temp isn't too bad now but my only concern as we approach the summer is the higher air temps that will push this thing over that 220 240 mark. There is no roof or doors so no need to worry about cabin insulation for now. Don't know much about the drivetrain, all I know is its a 727 hooked up to the original t-case. Thought about implementing the 1996 Ford Taurus cooling system, still doing some research on it.

Really appreciate all the help and input everyone.
 
I see you have a cross flow radiator, FWIW and IMO I would put a stock radiator with good shroud which you may not need depending on how the elec fan is set up. I do not like the elec fans with no housing or shroud, those are for trans coolers, etc.. IMO. Again your temps are not that bad, any idea what the water pump is on the engine ? might need replacement ? Thermo condition ? all gunked up or clean ? opening properly or restricted flow from crud ?
 
in addition to the good comments (bigger radiator, fan shroud, etc) above, adding an oil cooler will help stabilize your engine temperatures.
 
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