Radiator Questions??

[Shelly Harris]

My 1974 Mark IV is running hot. With outside temps over 90F and the A/C on, the temp light and buzzer go on. I put in a new water pump and fan clutch last fall and thought that would do the trick, but it hasn't. So I'm going to change out the radiator. I have the choice of a copper core $190 or aluminium $210. The cheapest one $160 doesn't mention the material of the core. What is the best choice here?

Thanks

[Barry Wolk]

I had to have the radiator on my '77 TC replaced when it had only 14,000 miles on it. It was 26 years old at the time. Unfortunately we were on the road when it happened and cost me $450.:mad:

The bottom half of the core was plugged solid as the channels run horizontally. The symptom only expressed itself at highway speeds. The faster I went the hotter it got, which seems counter-intuitive. The engine was obviously making more heat at higher speeds that the limited core space could handle.

How many rows does the original have? I opted for the severe duty radiator they put in Crown Vics. I believe it had 4 cores instead of 3, or 3 instead of two, I can't remember.

A thicker radiator will make warm up take longer but will provide much better summer cooling. If you get stuck in lovely Chicago traffic frequently it might behove you to install an auxillary fan using a bypass switch inside the car to provide additional control. You simply wire the two switch contacts in parallel with the thermostat wires.

If you do an antifreeze swap every few years, even a cheap radiator will serve you well.

[Mad Scientist]

I would expect copper to dissipate heat slightly better then aluminum, but if you are building a dragster aluminum is better because it is lighter.

Height and width have more effect on cooling the thickness, but in all cases bigger is better.

Is radiator painted flat black? This also makes a big difference.

Is there a shroud around the fan? This causes air to be drawn through the entire core and not just the portion in front of the fan.

If still a problem, consider a different fan. For example on the MKII with AC they added an extra fan blade.
Also going to a smaller pulley on the water pump will cause it and the fan to run faster.

[Shelly Harris]

Thanks for the information. Mine is original and the vehicle has 65k miles on it. It sat for many years in an Indiana barn. Being that the channels run horizontally there must be plenty of crap lying in the bottom section. Stock is 3 core. There's a stock shroud around it. Don't know where an aux electric fan could fit in... hopefully a new rad will be the trick. I just ordered the cheapest one I could find. I have no problem with changing coolant every couple of years.

[Barry Wolk]

My old radiator was twice as heavy as the new one.:eek:

[Mad Scientist]

It sat for many years in an Indiana barn. Being that the channels run horizontally there must be plenty of crap lying in the bottom section.

Agree.
Seeing that it does have a fan shroud, which is good, the only place to put an auxiliary fan would be in front assuming there is room. But a pusher type fan is not as efficient as a puller and the typical electric fan is anemic compared to the amount of air that the engine driven fan can move.

That being said I can’t believe Ford would have built a car with AC that couldn’t be used in hot weather. A nice brand new clean radiator should do the trick. It probably would be a good idea to have the engine flushed out at the same time.

One last point after the engine has been running for awhile turn it off and feel the entire surface of the radiator, if one area is noticeably cooler (bottom?) then it is clogged up.

[Continentalfan]

I'm dealing with a hot running MKII that ran regular for the PO and also when in a shop for touch up and engine detail recently. I thought that perhaps the thermo was sticking but removed and put in pot of water and heated on stove and it opened fine at 160 degrees. Did notice, however, that the MKII thermo opens a trap door to allow water flow and that trap door must need to be lined up with the direction of flow through the thermo housing or else it appears that it will prevent water flow and cause turbulence. Have re&re and lined it up but too late for test drive tonight. Will get at that on the weekend and report findings. Meantime has anyone else felt that the thermo should be lined up to permit smooth flow of coolant?

[Barry Wolk]

Was that an original bypass thermostat or one of the aftermarket units made in two pieces?

[Shelly Harris]

I'm dealing with a hot running MKII ....

My MKIIi runs hot too, except when the outside temp is less than 50F.

I have a 160 thermo installed. In the summer my MKII runs at the very top of the "normal range" on the instrument panel, never in the middle. If the outside temp goes over 85F then it goes higher between the top of normal and the extreme high. When the outside temp goes lower then 50F the gauge is barely in the low normal range. Lower outside temps and it get's near but never into the normal range. If I regularly drove in the winter i'd have to put in a higher degree thermo otherwise I wouldn't have heat.

[Continentalfan]

appears to be the original style bypass thermo..no date that I can find but definitely not a new one.. There are numbers on the unit that could be either 86 or 98 and with some of the other codes that cleaned up to read would say it is 86. it's a one piece unit.

[Barry Wolk]

That sound like an original. If it opens, it's working. I don't think that its installed direction matters. I would suspect one of two things. One would be a clogged radiator. The vertical tubes can easily get plugged at the bottom. They can easily be cleaned to restore better flow.

The other, more common, problem is having your spark too far advanced. If you're using the timing marks they could be off. Try vacuum tuning instead of using a timing light.

[Hal W May]

Barry: Excellent info on vacuum tuning-works great-except that I found that a little retarding from from peak vacuum cures mines tendency toward pinging at hi speeds.

[Barry Wolk]

That was Pony's recommendation, too. I tried it on my '68 460 and got the rpm down to 400.