Topic: Flathead Overheating


guardhawk74    -- 10-25-2010 @ 7:42 PM
  I drove my 49 merc on Saturday for the first time since restoration. It has the original 110 hp flathead engine. It started overheating within five miles of driving it. It got so hot it actually turned the green paint black near the carb. I checked the thermostats and they both open at 175 degrees. The water pumps were rebuilt. Any suggestions would be appreciated.


Old Henry    -- 10-25-2010 @ 10:57 PM
  My favorite idea from the several discussions there have been lately (today and on the 11th)is to first determine if the engine is really overheating, i.e. is it boiling over? And, if not, what is the real temperature of the water in the engine when the guage reads high? If the engine isn't boiling over, you should be able to remove the radiator cap when it's hot without the water boiling out because the radiator cap is very low pressure compared to modern engines. If you can open the cap without boil over, stick a thermometer in the water and see what the temperature really is. (I used my wife's candy thermometer. She didn't like it so I bought my own.) If the temperature is below 200 you're not really too hot, in spite of what the guage says.

If it is too hot, then you can try some of the ideas from the earlier discussion here: http://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=1988

Still Old Henry


4dFordSC    -- 10-26-2010 @ 4:08 AM
  You can also use an infrared laser thermometer to measure engine temperatures (e.g., http://www.buy.com/prod/non-contact-ir-infrared-digital-thermometer-laser-point/q/sellerid/23962916/loc/20269/214692516.html) Perhaps not as cheap as a candy thermometer, but faster and less cumbersome.


47Jack    -- 10-26-2010 @ 6:06 AM
  I had picked up on the earlier thread about overheating. My 47 truck had the gauge pegged hot but I used an infared thermometer and was able to get a reading of my heater core while I was driving. It indicated that my running temperature was 153 degrees. After climbing a mile long hill the temperature increased to 176 degrees. So now I don't worry about the gauge being inaccurate it's just something that needs to be looked at down the road.

Jack


BrianCT    -- 10-26-2010 @ 8:39 AM
  I think that your burned paint is from the normal exhaust passage through the intake to warm the carb.
Probably not a problem.


Old Henry    -- 10-26-2010 @ 8:54 AM
  4dfordSC, I'm interested in your infrared thermometer but the link you posted about it doesn't work. Can you post one that does or give us information about it enough that we can find it ourselves?

Still Old Henry


supereal    -- 10-26-2010 @ 10:02 AM
  We have an IFR thermometer in our shop, but we don't use it much. The reading will vary according to the surface of the part being tested. It is useful mostly for finding a variance in the system that is hotter or cooler than the rest, such as heaters and AC. From your description, I'd suspect you will be looking for new or better radiator if the mercury thermometer confirms the high temp. Also, check for an exhaust obstruction, a frequent cause of overheating in old cars. If your Merc has an exhaust valve (flapper), it is probably stuck in a partially closed position. That would explain the burned paint on the manifold.


37RAGTOPMAN    -- 10-26-2010 @ 12:46 PM
  also make sure the timing is not retarded, this will also make it run hot,if it has power it probably is ok,
but just check it anyhow,and also if the vacuumn advance is working,loose belts, also make them run a little hotter,
lets hear how you made out,
37RAGTOPMAN an KEEP on FORDIN,,,,,,,,,,,!!!!!!!!!!!!!
clog in exhaust is another,
how is the radiator ? was it cleaned out ?


guardhawk74    -- 10-26-2010 @ 4:16 PM
  Thanks everyone for all the suggestions. I checked the thermostats and they opened at 175. I took them both out and and ran the car for about 20 minutes and the gauge went just half way up. I havent had a chance to drive it and wont for a day or two but with the stats it went to hot in five minutes. The exhaust is clear. I will look at it closer over the weekend. I've attached a picture of the merc


guardhawk74    -- 10-26-2010 @ 4:21 PM
  Forgot to add, the radiator is the original to the car and was recored and seems to be in excellent shape.


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