coolant in a 12

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    What is the best coolant to use in a 12? Rught now I have straight water, but you can hear it boiling when you turn it off. Thanks Doug Vogel



    I use water and rust inhibitor in my ’34 1240A. You have some more tuning work to do because you should not hear it boil unless it is very hot outside.

    Check your basic ignition timing and your synchronization. Is this a new radiator core or the original?

    Do you see the temp gauge shoot up when you shut the engine off? I used to but I don’t any more. (A new radiator core fixed that problem).



    Check your lower radiator hose to be sure it is not collapsing. It should have a stainless spring or pipe in the lower hose. Also, you would be surprised to see how many cars have bad pump impellers. And as Bill said, check your timing. Ed


    The car has a new impeller, but the original radiator. The lower hose has a pipe in it with a drain . Timing is most likley my problem. I will check the head temp. again. I thought it was running at168 degrees. Thanks again, Doug


    I thought of something else. Do your water jacket covers have the soldered on tubes that direct streams of water to the hot spots?

    Another possible cause if they’re not there.



    Yes it has the tubes. I plan to drive it this weekend so will check it out more carefully . Doug


    Hello Doug,

    For what is is worth, I learned a long time ago from the collective knowledge of the Society that anti-freeze in our old engines likes to foam up and ends up pushing coolant out the overflow. Plain water is actually a better coolant and transfers heat more readily than ethylene glycol anti-freeze. However, plain water is also bad from a corrosion standpoint (as Bill pointed out above). About 5 years ago, I started using Pencool 2000 as an additive in my cooling system. It acts as a corrosion inhibitor and water pump lubricant. It is used in diesel truck engines and is available from shops that service semi trucks. There is no anti-freeze property to Pencool 2000, but during the driving months, I have been very happy with its performance in my Pierce.

    Happy Motoring,



    My experience with foaming was baffling. Then, I discovered that the way that antifreeze foams is by having air infused into it, and the only place that can happen is the water pump. I had it happen on a ’34 with the shaft on the pump, and ended up machining a new shaft and installing new seals instead of packing, two modern seals, facing in opposite directions. The second time was due to lack of lubricant in the water pump, and air was being pulled in through the grease fitting. Think this happened in Asheville, and it may have been Bill who had a tub of the correct grease, installed, problem gone.


    Yeah, that was me. I never go anywhere without that grease. Someone always seems to need a capful.



    I thought it was, I thanked you then and thanks again! Couldn’t figure out why car was losing coolant. Wonder how many foam or overheat issues are related to not having your “magic tub!”” Best dc”


    Thanks to all for the advice. I had no over heating on the last trip. So on to the next question which I will post in the next discussion. Thanks Doug



    I battled overheating for years…with new core. The most important steps for me were having the pump/vane clearance right to stop sucking air and getting the timing advanced far enough. It now is good with an anti-freeze mix but that’s a climate and storage issue to balance. With either 8 or 12 a spurt at shutoff will occur unless everything is perfect. Usually it is only a few ounce and not a concern at that level. Foaming must be eliminated entirely. Gano see through in-line filters are helpful with that issue,but probably cost a point penalty for judging.

    Anyone who says they have never had any overheating issues with a V-12 probably doesn’t do a lot of driving, but it can be managed to success with the right effort. After all, Seagrave used these for many years to run fire pumpers while not moving at fires.

    Temperature gauge readings are taken at the right rear of the engine which is the hottest place in the cooling cycle and can be misleading.

    Everybody has given you the right advice so far. Good luck.



    The Pencool product Chris mentioned is now called “Pencool 3000”. I use it in both of my cars and have had very good luck with it. There are some other “similar” products on the market which will foam. Norosion is one that foams. I was sent some on a promotion. On a tour, I ad to flush it out as it foamed so badly. Another driver on the same tour had had the same problem with it. When the coolant starts foaming. most of the cooling efficiency is lost.


    Some of the brands (e.g. “Hastings Cool”) require 30%-60% anti-freeze to be effective, which I infer means that the anti-corrosion in that brand is a supplement to that in the anti-freeze and therefore not sufficient by itself.

    I heard that Pencool makes both “2000” and “3000” — one is for use WITH a usual mix of anti-freeze, the other with straight water. I haven’t checked their website.



    Yesterday it was 102 here, I took the 36 V-12 for a spin before loading it in the trailer for the meet this week. At 45 mph for 10 minutes the temp was 169 and at a stop light (about 3 mins) it went to 181. I am just running regular coolant. I have run the car almost 20,000 miles now and the only time I ever overheated was climbing Mt Washington, 7 percent grade for 8 miles as I remember. I’ll post some information after the meet on cooling systems and new products. Ed


    V-12 Temperature update. Seagrave trucks had a heat exchanger in line with the fire hose pump when it was running so it would not overheat. Here is some new interesting information. While at the Rochester meet and on tour with my 36 V-12 we were running the back roads at 55 mph with 5 adults in the car. The temp held rock steady at 169 degrees. We were running normal 10 percent alcohol in the gas as it is the only thing available in Massachusetts. We had the opportunity to fill up in the Minnesota boondocks with regular gasoline with no alcohol in it. I have never ran my car on “normal old gas” since I have owned it. The pump was marked for collector car use only, not modern cars. Filled up the tank, and I took off down the road. Within five miles my car was running at 142 degrees for the entire day as well as the rest of the meet. It was actually opening and closing the shudders in the grill and cycling the thermostat open and closed from 138 to 142 for the next two days of the meet. I have never seen this happen on my car for the 20 years I have owned it. Ran it around home and still had the same results, but I have not filled up with our gas here yet. While I would believe a 5 degree drop with the “good old style fuel” I would not have believed 25 degrees without seeing it for myself in my own car. I will fill it up and give everyone an update soon with the 10 percent alcohol gas here in Mass.


    I am going to start a new post on cooling and fuel systems. Ed


    Ed, the alcohol mix/temp change is amazing-keep us posted.



    Thanks Ed, I think this will help a lot of us. I will take a few drives and take the old girls temp. Doug Vogel


    I went for a one hour drive today and stopped several times to check the water temp. By pointing the infered down the radiator I was able to just measure the water temp. which stayed solid at 181 degrees, and then would start to drop rather fast. I only watched it until 165. So maybe its not running as hot as I first thought. Is this OK ? I am waiting for a resonator for the exhaust and will then wrap most of the exhaust to help get the heat away from the engine and passengers. Doug

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