Cooling system upgrades when adding a/c

peeeot

Well-known member
My '60 Fairlane is having trouble keeping cool with the a/c on, even (especially) at highway speeds. It does not overheat but the temp moves into the higher third of the 'normal' bar where it is normally in the lower third. It will also puke coolant from the surge tank if it isn't allowed to cool off a bit before killing the engine.

It has the stock 223 cooling system (original radiator, 4-blade fan). It has no trouble keeping cool with a/c off even in the high heat of summer here in NC, though the temp will creep up at idle or low speed operation. The car has under dash a/c added on with a sanden compressor and vintage ford evaporator. The compressor is driven by the water pump pulley rather than by the crank pulley--the water pump is dual sheave while the crank is single. The addition of the dual sheave pulley meant the fan was moved 0.25" closer to the radiator, but it is still unshrouded.

I am wondering whether I need more airflow or more cooling capacity or both. I know usually the factory a/c cars get a beefier radiator, a 5-blade fan, and perhaps a beefier generator as well. I am thinking the radiator is the weak link because the highest temps are attained on the highway.

Replacement radiators are scarce; maybe I just need to find a v8 radiator? What do you think?
 
Since you mentioned that, mostly, the problem occurs at highway speeds, I'll throw a couple ideas out.

Do you know what thermostat is installed? If there is no thermostat, the coolant might be circulating too quickly at speed to spend enough time in the radiator to cool properly.

Check the lower radiator hose, see if it starts to collapse when you rev the engine. If it has the original style hose, there should be a spring inside to keep that from happening. Over the years it may have disappeared. At highway speeds, this can virtually shut off the flow of coolant.

The running warm at slow speeds may indicate a radiator issue, you might not have to replace it. Those old radiators can sometimes be "rodded out" by a competent shop to restore their flow like new. If not, a new core might just solve the problem. It could also be a fan issue but I would alter the fans and/or add a shroud after I'd covered all the basics.

Let us know what you find so we can help you take this to a successful conclusion. Good luck with it.

Lou Manglass
 
Hi, X2 on that advice. I would maybe retard the timing a couple of degrees. That might help. The overflow tank is a great addition. I wonder if you have too much coolant to begin with. Your radiator should be full to the top and you should have a little in the expansion tank (when cold). When it gets hot the coolant will expand into the over flow tank, and back onto the radiator when it cools down. I use 2 bottles of "water wetter" in my Ford Flathead which are thought by many to be prone to overheating, and that along with a good replacement distributor I never run hot at all. I have a digital thermometer and with it you could easily check the temp of the water flowing out the thermostat housing. By the way, when cold, remove the radiator cap and start it. Coolant should not ciculate for a while. If it circuates through the top tank right away your thermostat is missing or stuck open Good luck
 
Hi update. Make be sure to check your ignition timing, if it is off let's talk about an adjustment
 
Finally, an update!

I brought the radiator in to a shop to have it cleaned and checked. They said it was flowing fine and should be able to handle the extra cooling load from the a/c ok.

I also checked the thermostat and found a 160-degree unit with obvious stress cracking. I have obtained a 180 degree replacement. I suspect that the thermostat has been the main problem because I've noticed that the engine runs warmer or cooler at various times even without using the a/c, which indicates the thermostat isn't really regulating the temperature.

I'll report back with any changes in cooling performance after the repairs are complete.

Question: doesn't retarding timing usually increase operating temps?
 
Hi, yes you are right. Sometimes my typing gets behind what I am thinking. Good luck
 
I cant's believe that it has been nearly a year since I started this topic! Time flies.

Turns out I am still having problems regulating engine temperature, especially on the highway, with or without a/c on.

When I posted last, I had the a/c compressor driven BY the water pump. Now, I have a 2-sheave crank pulley and the compressor is driven by the crank on its own belt. I had been concerned that the extra load of the compressor on the water pump pulley was causing slipping and reducing coolant flow. That potential issue has been ruled out.

I want to think that bringing the radiator to the shop and having it cleaned/tested would mean I can rule it out as well, but it wasn't rodded out and I am suspicious of it still. I seem to recall checking the lower radiator hose and finding no trouble there.

I did discover today that my load-o-matic advance can is leaking. I am still getting some advance but it's very possible that timing, especially high rpm timing, is slow. I have a NOS advance on order.
 
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