V-12 Cooling

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    Hi everyone,

    Has anyone tried to let their 12 cylinder engine idle to see if the water temperature will stabilize with an ambient temperature of say 70 degrees? My ’34 1240A won’t do it. If I just let it idle it will eventually boil if I don’t shut it down. We’ve rebuilt the water pump paying special attention to the vane gap so I believe that I have enough circulation.

    My specific unpleasant experience was driving home from the Glidden Tour. We’d been cruising at 55 mph for hours and hit a traffic jam coming into the Chicago Area. It was raining, the temp outside was about 70 and we had a slight tailwind. After about 10 minutes of creeping I had to pull over and shut down the engine because it was at the point of boiling. I’d tried using the hand throttle to raise the idle significantly to try to cool it down but nothing worked. All tuning parameters are normal (correct timing, not running lean, new plugs, etc).

    The core is original and the tubes are clear. I suspect that the heat transfer rate between the tubes and the fins is not where it should be and with the lower air flow at idle it can’t transfer enough heat.

    Has anyone made a fan shroud for the radiator? If so, did it help?

    I realize that the obvious action is to replace the core, but while I’m doing that I’d like to know your experiences with shrouds or pusher fans located on the front of the radiator.

    Thanks in advance for your comments.



    check to see if the radiator ‘vanes’ are actually attached to the tubes. These come free sometimes, or were never connected.

    Are your return hoses collapsing. Have you run a real flow test on the system. Sure you don’t have a head gasket leak, or a crack in the heads or block. Temperature should be 165-175 degrees. Could you have an inline thermostat in the top hoses, and one or the other are frozen closed or highly restricted. Could your water pump be sucking air into the system causing cavitation in the lines. The cooling system is often a problem for Pierce owners. Sooner or later we all have to go on a ‘search and destroy’ mission and clean-up the whole system. Restoration Supply sell a closed system coolent that is basically straight antifreeze with rust inhibitors, with NO water added. This gives a slight edge. I am running 165 degrees at idle with it. Yes some have added a shroud, but the placement is very important, as the fan can give LESS flow if not set correctly. Good luck, I’m not a mechanic!!

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