I guess originally the water pump maybe had the outlet coming out the pass. side from the looks of the depressions within the crossmember.

Because the engine sits down low in the frame I do not have room for my preferred water pump driven fan blade so I am going to have to visit the local scrapyard in hopes that I can find a large electric to mount to the backside of this rad.

There is only about 8.5 inches from the center of water pump shaft to the bottom rad hose!

Can anyone tell me how I would wire in this fan so that it turns on when the engine requires it too.

Electrical is my weakest area and at this point would not know where to begin except wiring in a toggle switch somewhere or making it always on which I do not want to do.

 

The fan needs to be controled with a sending unit in the water jacket through a relay to control the high fan motor current .Perhaps someone will jumpin with a wiring diagram for you .

 

Thanks, on my way to junkyard and I will add the sending unit to my list of what needed, knowing this forum by the time I get back someone will have already posted a wiring diagram and an easy to understand explanation of what I need to do.

 

The fan will be wired to the relay. The relay switches battery to the fan. The relay's coil (control input) will be wired to the sending unit. The sending unit is typically in the intake manifold or sometimes in one or both heads.

 

I tried to paste in a basic schematic but I'm not having much luck.
If you google "basic cooling fan schematic" you should get tons of info.

Bobby

 

Thanks guys, as luck would have it there was a 1982 postal jeep there with its usual array of mix and match parts, 7 bladed cooling fan that measures 8 inches from center shaft to furthest blade.

I googled 8 inch fans yesterday and came up with nothing so I dont know if maybe it was originally designed for these postal vehicles?

I also know it was a 4 cyl but considering the stop and go traffic these jeeps put up with and the fact that it has 2-3 more blades than the stock 351 fan and lastly its blades are less than two inches shorter than stock 351 I think I will be OK.

I just need to come up with a different upper water route and am working on that now, it just barely wacks the upper hose.

 

I don't think that a fan meant to cool a 150 cid 4 cylinder engine will be adequate for cooling a 351 cid V-8. I would look at investing in a new electric cooling fan. They usually come with a sensor and a relay and are easy to install. You should measure the radiator space that you have and get the biggest that you can find. Usually a 16-17" will work. There are several suppliers that carry them Sppedway or JEGS are but two.

Here is a whole list from JEGS: http://www.jegs.com/p/Derale/Derale-Dyno-Cool-Straight-Blade-Electric-Fans/1321867/10002/-1

JEGS has this low profile, reversible 16 incher on special for $58. It comes with a probe and thermostatic relay. Just check the dimensions to see if it fits your truck: http://www.jegs.com/i/Derale/259/16916/10002/-1?parentProductId=1321867#moreDetails

I think that you will be happier with that and it will look better. Since it mounts flat against the radiator you can safely remove the shroud which will give you a bit more space to work on maintaining belts, hoses, etc.

The other problem with the small fan in your picture is that it uses a viscous coupling that decouples the fan at highway speeds. Those are notorious for going bad after a few years. (http://en.wikipedia.org/wiki/Fan_clutch) The last I checked they were more than the price of an electric fan.

 

Thank-you for taking the time to post that info Pete, at this point I am so close to finally driving this thing that I have checked the fan off my list until some point after I am driving and see how it does as far as cooling.

Dropped my driveshafts off just now and its getting closer.

I just cant go back now but will keep the info you posted in mind.