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jesseg 05-19-2013 05:10 PM

over heating problems. need help.
I'm having problems with my CJ-5 and overheating. Currently there is no electric fan because I can't find one that will fit. I only have 1 3/4 between the radiator and the grill. What I was wondering is there an electric fan out there that is this thick? Or is there another cooling option that will work?

kovic 05-19-2013 05:54 PM

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Should not have to have an electric fan. If it is overheating there is an underlying problem that needs to be figured out. Is this stock?


jesseg 05-19-2013 07:01 PM

No it's a 71 CJ-5 I put a 350 small block Chevy in it it at the perfect temp when driving over 15 mph any speed under that it wants to overheat. The fan on it now is a 15 inch 6 blade and I believe it's not sucking enough air through it to keep it cool.

wellmax 05-19-2013 07:38 PM

with this setup your coolant system must be in perfect working condition to keep that big engine cool.

fill the radiator with water, with radiator cap off,

pull the lower hose off the radiator and see how fast the water flows out of the radiator, it should gush out, if the radiator is not stopped up. if it just gulps out, then you may have a partially stopped up radiator, take it to a radiator shop and get it checked. you will need the same size radiator that was used in the truck/car the motor came out of.

do you have a new thermostat installed and is it installed correctly, some can be installed backwards.

are your upper and lower radiator hoses in good shape, if they are soft and collapse, that will cut off your supply of coolant.

how is your fan clutch, if it's never been replaced, then replace it as it needs to be replaced.

is your fan shroud in good order, it must be in place so the fan can pull the air through the radiator and not around the radiator.

these are a few first steps to check

jesseg 05-19-2013 09:10 PM

Everything is brand new, the motor the radiator The fan. The thermostat is new and installed right and the radiator flow is great. Thanks for giving me a list to check and it all is working order.

kovic 05-19-2013 09:17 PM

31 Attachment(s)
Did you rebuild the motor, is it crate, or whats the story?


jesseg 05-19-2013 09:27 PM

It's a crate motor 100% new.

wellmax 05-19-2013 11:24 PM

if all is in good order then you must not have enough radiator for this engine.

if engine timing is correct, carb set right, then you should be able to cool the motor at low speed.

some other options: there is a material you can add to the coolant to help it transfer more heat, super cool or some such!!!!!!! check it out on the internet

does your fan pulley have a clutch or direct connect drive? if fan clutch, it may be slipping and you will need a direct drive fan to cool the engine. I know you said all is new, but new can be defective.

water pump on motor, you did say all is new so you should be able to look into top of radiator and see coolant moving across the top of the radiator, if so pump is working, but how fast is coolant moving, if very fast you may have a high capacity water pump and its moving the coolant so fast through radiator, it is not having time to cool down the coolant.

but if it works at speed, then your problem is low speed cooling,
Question: what can you do to increase low speed cooling,

more air flow, bigger radiator, additional coolant maybe add a secondary coolant tank in system, change of coolant,

high speed cooling is from more air moving across radiator or more coolant moving through system.

these are the areas you are going to have to work on. I have seen jeeps with big V8's have a second radiator in the rear behind the seats to help cool the motor at low speed.

again, good luck and let us know what works,

fastest way to ruin a good motor is to let it run out of oil,

the second fastest way to ruin a good motor is to let it get hot, due to lack of proper cooling.

I have heard of this problem many times, big motors with low speed cooling problems.
do you have a hot cam in motor, anything to make extra heat??????????

jesseg 05-19-2013 11:41 PM

Thanks I will check out this coolent your talking about the radiator is a 4 core heavy duty. It is the biggest raiator I can fit in it as I had to cut out the fenders to fit it in

wellmax 05-20-2013 12:13 AM

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you did not mention if you still had the fan shroud in place, I think the fan shroud is very important in the proper operation of the cooling system.

as you mentioned you cut the jeep to mount the large radiator, then you may have holes in the fan shroud system. these hole could allow air to bypass the radiator, all incoming air must flow through the radiator to have proper cooling.

the fan must direct all incoming air through the radiator and the fan shroud insures this happens.

picture of a fan shroud is attached.

have you tried turning on the heater when motor starts getting hot. if that helps then you are close to solving the heat problem as the heater acts as another radiator to help remove heat from the system.

jesseg 05-20-2013 11:14 AM

The fan has no clutch. I'm going to look into the coolant and the second radiator option. Thanks for all the ideas.

82JeepCJ7 05-20-2013 11:31 AM

I'd stay away from electric fans. Keep the mechanical fan. Anything in front of the radiator? Winch? Pics?

Davis77Cj 05-20-2013 11:49 AM

Another question to ask is the tuning correct? Because a poorly tuned carb can cause the motor to run hot

braguenavy 05-20-2013 12:36 PM

I use a dual electric fan with an automatic thermostat so it comes on whenever it gets at a certain temp. I love it. Works great. Never overheated.

jesseg 05-20-2013 12:43 PM

I want to use an electric fan but I have no room for one. Only have 1 3/4 of space I don't think they make one thinner than 2 inches.

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