72 351C starts to overheat at idle

[edward24]

I installed a 3 core aluminum radiator and now fan is now too far into the shroud.  I have a 3/4in spacer on the fan.  To increase the water flow I removed the Thermostat and just had a reducer in its place.  I am considering installing a electronic fan.   Any thoughts if this will help the temperature problem.

[Mustangmike]

I am trying to determine if the fan is the problem or if there are other reasons.  Before installing the aluminum radiator was the car overheating?  There seems to be another issue since the thermostat has been removed.

[edward24]

I am trying to determine if the fan is the problem or if there are other reasons.  Before installing the aluminum radiator was the car overheating?  There seems to be another issue since the thermostat has been removed.

I had a old 2 core radiator which could have been an issue that is why I installed a 3 core.   The car did not overheat to this degree before with the old radiator. The water pump is new.

[1969_Mach1]

When does it overheat?  Usually, overheating at idle is insufficient air flow through the radiator.  Overheating at speeds above 30 mph is insufficient coolant flow.

What type of fan are you using on the motor?  After market flex fans don't work that well at all.

For thermostats, I've had best luck with Stewart brand high flow thermostats with the additional bleed holes.  I don't know if they make one for a Cleveland motor.  But I think you should have some type of high flow thermostat installed, probably 160 degree.

What is your base and total ignition timing set at?  If it's not advanced far enough the motor will run hotter than it should.

Is the motor stock, has it been rebuilt, is the cylinder bore stock or oversize?

I'm not too familiar with Cleveland motors, but isn't there some type of restrictor installed in the block down below the thermostat?  I know two people that have had that missing and severe overheating problems occurred.

Photo I found on the internet of a replacement of the factory installed restrictor.  Apparently somebody reproduces them.

[edward24]

Thanks for the info - It will start to overheat in traffic.   Move at a good speed the temp goes down.  I need to get the fan further out of the shroud.  Will purchase a 1/2 space but that still will not move it half way out.

[edward24]

The engine is stock - put in new water pump, heads, cam, oil pump.

[1969_Mach1]

Sounds like you have an air flow problem.  I doubt moving the fan 1/4" will make any difference.  What type of fan is it?  If it's an aftermarket flex fan I'd swap it out for something more original.  In 1972, wouldn't that have a clutch fan assembly?  I'm not certain but by 1972 most cars came with clutch fan assemblies.  My 351 Windsor always ran hot with an aftermarket flex fan.  I installed an OEM Ford clutch fan assembly and the temps dropped down significantly.

[edward24]

Have the original fan not a clutch fan.  After your suggestion of a reducer found a mustang cleveland website that talked about the engine overheating and the type of reduce to use.   Purchased it and will install is and post the results.  Thanks

[edward24]

I purchase a new restrictor and thermostat.  Pulled the old one out and installed the new modified plate with a 190 therm.  Ran the car at idle and the temp continue to 230 before shutting down.   Any advice or suggestions are welcome.

[1969_Mach1]

Is this correct, it overheats at idle but cools back down when driving over 30 mph?  If so, that is indicative of insufficient air flow through the radiator.  But, I wonder why you installed a 190 degree thermostat?  I would have installed a 160 degree thermostat, 180 degree at most, and a high flow style if it's available for a Cleveland.  If you have to use a standard thermostat make certain there is a small bleed hole in it, about 1/8" diameter bleed hole.  It helps purge the air out of the system and balance the coolant pressure on both sides of the thermostat.

I wonder if that themostat you installed is opening or you have a big air pocket trapped in the cooling system?  What brand is the thermostat?  Maybe try a different thermostat and lower temp.  If you are getting one from a parts store look for Stant brand and preferably their superstat line.  Napa's thermostat's are Stant brand.

Let us know what you find.  Hopefully this is a simple fix and not something more involved like a head gasket.