Over heated Ford (Mercury) Engine on my F8

[cletrac (RIP)]

The first thing I'd do is ditch the thermostats. That's an old wives tale about needing them. Those pumps aren't that efficient that you need to slow the water down. If the flattie is running around 120 without them and conditions start it heating up you've got more leeway than if you're starting at 180. If you look at the LRDG pictures the trucks usually had the hoods removed to allow for more air flow in the hot conditions.
Did you do anything to clean the water passages on the engine and rad? If not that can cause problems. If that's the case put some Drano in the rad and run it for half a day then drain and flush. It's amazing what that gets rid of.

[Jim Price]

David,
Thanks for the advice! The engine was clean and the radiator a new one so neither of these contributed to the problem.

Regards,
Jim

[Phil Waterman]

Question for you are the thermostats new? Did you test them to be sure they are actually opening at the rated temperature? I've been doing test on all the thermostats I've put in rebuilding engines last couple of years and discovered a interesting thing. Brand new fresh from the manufacture thermostats are often slow opening the first dozen or so times they open and close. Which will cause and engine to run hot the first few times you bring it up to temperature. There is a big difference in how fast heats the engine pushing the truck down the road than running the engine stationary.

What I do now with new or even old thermostats I test them and cycle them on the stove in a pot of water. Bring the water up to the rated temp 140 180 what ever then dip (using tongs) the thermostat in see how quick in opens. Then dip it into cold water. Do this several times you will be surprised that with a new thermostat it will open a little faster each time.

[cantankrs]

Originally Posted by cletrac

The first thing I'd do is ditch the thermostats. That's an old wives tale about needing them. Those pumps aren't that efficient that you need to slow the water down.

Hi David, I only have experience with a 70's OHV V8 down here in warm WA, and people had told me to ditch the thermostat but I discovered that on a really hot day having no thermostat just seemed to heat the water in the radiator faster until the whole cooling system was way hot. Having a thermostat in it allows the radiator contents to cool a bit more before its demanded. Presumably my situation came about because the water pump was fairly efficient - which perhaps is a vital condition in your statement.

Also with these old vehicles on a stinking hot day you can't even keep the motor running sitting in a drive-thru at McDonalds or wherever without the temp creeping up and up.

Remember that Henry Ford's SV V8 has the exhaust ports running across the block between the cylinders. This contributes to a hot motor thru its design. A clean radiator and functional waterpumps would seem necessary.

Also who's paid good money to have their radiator 'professionally cleaned' only to find it still has blocked cores cos they did it ultrasonically instead of removing the bottom tank and rodding it out like it needed? You only find out after things have gotten hot again! That nice fresh black paint ain't a certification!

Phil, from the same vehicle I can confirm that thermostats certainly can't be trusted from new because I then had to play with a string of thermostats that were opening later than their rated temps. In my situation I settled for a 160 thermostat that tested OK and seemed to resolve the issue with that type of motor.

Regards

Alex
--
M3 Grant, Val, Ferrets, WM20, CMP's

[Mike K]

the idea of having thermostats is to create a temperature difference between the engine block and the radiator ... this temp. difference siphons the coolant around .. hot water rises, like in a home hot water system ... If you remove the thermostats, the whole system is almost at the same temp., and you lose the thermo-syphon effect . Many veteran cars have no water pump at all ...they soley rely on the thermo-syphon thing to circulate the coolant around.

Those SV Ford lumps are HOT motors ,it's a design thing ,the exhaust gas ports are such that the motor runs hotter than it should.

Mike

[cletrac (RIP)]

Way back in the day vehicles didn't have very efficient heaters. Henry Ford took note of this so when the flattie was being designed he insisted that they run the exhaust ports through the block. This would make the motor run hotter and hence a more efficient heater. The rest is history!
Any motors from the fifties and earlier that I've had anything to do with seem to cool better with no thermostats. Those old water pumps don't pump that well at the best of times so you don't want any more restrictions that you can avoid.
Another thing if a motor's running too hot try playing with the spark timing. A few degrees here and there can make quite a difference but on a Cab 11 it's a pain in the butt to do. Sometimes a size bigger on the carbs main jet helps too.

[gjamo]

Back when I was a kid on the farm at Corowa everything that ran ended up being powered by a blitz or carrier motor including ski boats and tractors. The trick we found as long as all other cooling system components were in good condition was to run an extra pint of oil in the sump.
85% of engine heat goes to oil to be disipated. We never suffered with oil foaming or pumping it out and motors ran hot but acceptably ever during harvest in a header.