Overheating Flathead
- Thread starter millcroft
- Start date
krackerjack1951
Well-known member
my merc runs approx 100 degrees hotter than the ambient temp in normal driving..if i get in the throttle pulling a long grade or a strong head wind the temp climbs to 205 in july carolina weather,185 statts 50/40 antifreeze..my elec fan is used in stop and go traffic if needed....i run stock distributor with petronix,timing at 4 degrees,,mild isky ,block bored @60..i have seen the temp climb driving into the afternoon sun maintaining 70 mph,,back off the throttle ,,the temp falls to 180 quickly...less fuel/less heat in an engine that was designed for 55mph on 45 mph roads..just my way and it works for me!
Talkwrench
Well-known member
Every car has a thermostat(s) if you need to remove them there is something wrong with your cooling system.
wga
Well-known member
Krackerjack - these flatheads were designed when the octane was around 70 or so.
Now we use 87 + ethanol.
Interesting read from Red:
http://www.reds-headers.com/html/red_s_engine_talk_23.html
Now we use 87 + ethanol.
Interesting read from Red:
http://www.reds-headers.com/html/red_s_engine_talk_23.html
Dick I have tested modern 160 degree stats and drilled 6 or 8 holes in the flanges years ago and reported the results on this forum many times. These were installed in my 39 P/U which will sit and run at a fast idle for 2 hours in 100 degrees and never get over 180. With the modern stats like you have this same P/U went up close to 200 in 90 degree temps. I since put 180 HIGH FLOW stats in made by Bob Shewman 1-610-933-6637 or gadgiteer@aol.com and now it runs at 179 to 182 in temps from 55 to 95.The engines run best at this 180 temp, they are smooth and act the same all the time. Bob's stats are heavy copper and brass, mount in the upper hoses and have large flow openings that don't restrict the flow. Bob also makes a 1/2" ventilated spacer for under the carb that prevents carb problems due to hot gas. There are a lot of misconceptions on cooling these engines. The amount of coolant in the radiator, these are 22 quart systems, not 16 to 18. Less water gets hotter and don't cool as good. Fill the radiator up into the neck use a 4 lb pressure cap on radiators equipted for one or Skips 3 lb pressure valve on early radiators with the over flow off the top tank. The coolant will stay filled for months. Skip also makes high flow pumps that pump almost double the flow of ANY pumps available. Some will say the coolant flows through the radiator to fast but that's not true. I have done 100's of tests showing at least 20 degrees improvements every time. Air through the radiator is as important as cooling flow. The output of the pumps are in proportion to RPM's. The faster the speed the more coolant is moved with Skips pumps, other pumps slip and spin inserting air in the water. Water or coolant with air don't cool as good as solid coolant. I run at speeds of 65 to 75 on 100 degrees days for 10 to 14 hours straight at 185.Also a cooler engine makes the interior of the car cooler. Heavy traffic at low speeds or long idles are problems with these engines because of the poor movement of air by the fans. Skips pumps have cured 98% of the over heating problems on cars installed on. These pumps won't over come a bad radiator or internal compression leaks but have resolved the problems on at least 6,000 old Fords. Many have reported the results on FB. G.M.
FlatheadTed
Well-known member
Is it boiling out the water or is it dumping because of a loose cap .or has it a crack in the block .try block sealer ,Also a shroud can help I have done tests were you can get a drop of 15deg
dp1743
Member
I'm dumping out just a little coolant. Took a laser thermometer and fluid was at 200 degrees. Block at both pumps were the same temp. Is was checked today in 95 degree weather w/o thermostats. No indication of a cracked block and the cap is fine. The engine has less than 1000 since being rebuilt and blueprinted. It runs great, but I'm concerned about the temp.
Mike51Merc
Well-known member
These cars will dump coolant until the level reaches its "sweet spot".
If it isn't boiling over it's not overheated. Water boils at 212 degrees, unpressurized antifreeze at about 230, pressurized even higher.
Just as a sidenote, my OT Audi thermostat doesn't even open till 205.
dp1743
Member
Thanks for that info Mike. Mine is not "boiling over" (yet). I'm beginning to think the dash guage is not working right. My infrared thermometer is getting readings this morning after running for 15 minutes of 180-195. That's w/o stats. Fluid runs thru strong and the fan is doing it's thing through the rad. I' m running 20W-40 in the motor. Maybe if I went to 20W-50?
BUBBAS IGNITION
Well-known member
And yet another thought , if the stock distributor ( loadamatic) is not set up with the correct vacuum signal or the diaphram is leaiking then the ignition will run very retarded. Very retarded = overheating....
dude
Senior Member
Walker makes a fan shroud,497-1, that works really nice. It comes without the fan opening . you'll have to cut to fit. Google Walker fan shroud.
Steves46
Well-known member
You may want to consider installing a pair of mechanical gauges under the dash. I did this for my 46 and they provide accurate readings. One other thing I would like to mention is water/coolant mix. In Florida, I have been running with 1 gal of 50/50 coolant and the rest with distilled water and unless I get caught in slow traffic, my temp stays around 165 (no stats). You will find the cause-just keep troubleshooting! Steve
Flat Ernie
Senior Member
The stock distributor should be subjected to Bruce Lancaster's Navy Flotation Test. Throw it in the nearest body of water and see what happens - if it floats, re-use it. If not, get another distributor...
...and the man to see about a distributor is GMC Bubba. Get one of his distributors, you'll have more power, better ignition, more MPG, no chance of ignition-induced overheating, and you'll take 10 years off your life.
One other huge help for the '40 model coupes is to install a baffle between the top of the grille and the front of the radiator in the latch area. Cover this up - even with cardboard - and none of your cooling air will bypass the radiator up and over the top as the stock configuration will do. I fabricated a simple sheet metal plate held on with two small screws. Be sure the rest of the radiator baffles are in place too.
19Fordy
Well-known member
Here's an example of those panels Flat Ernie recommended. Mine are home made. They are made of 16 gauge sheet steel, but thinner metal could be used. Been using them for last 10 years. Also, be sure to install the rest of the stock grille panels.
Attachments
Last edited: