Losing coolant

36 ford

36 ford

Senior Member
I knew it was a matter of time before I'd have to put this out here..
The 48' merc engine in the 39 Deluxe I bought is losing coolant but it's not visible outside the engine. I see no coolant in the oil and it's not blowing out the exhaust. It seems to run strong so where do I begin? Should I look for a blown head gasket?

Thanks for any help you can send my way...

Phil
 
Put in 1 big bottle of Barrs Leak and give it a good night's rest. Sorry, couldn't help myself. How much are you losing? Could you be losing it out the overflow? What coolant are you using? If the engine is burning it, you should see white smoke out the exhaust.
 
Check the overflow on your radiator.

Then drain your oil. Coolant goes to the bottom, so it will come out first. (put oil back in before running engine, for best results:D)
 
I'm running close to straight antifreeze, 7 lb cap, no smoke out the back and no evidence in the crankcase. I have an overflow tank which was about half full , went to a local car show about 5 miles away and there noticed the overflow tank was empty. radiator was full though. I've pulled the plugs and they look normal, too.

Phil
 
I don't think you should ever run antifreeze stronger than 50-50. If you leave it alone after it looses a small amount does it continue to get low? It may be that its just getting over full?
 
The mix isn't the problem. If you have water in the oil after sitting over night the oil all go's to the bottom. Pull the dip stick and the oil level will be high with water on the bottom of the stick. Start the engine and the oil looks like a gray milk shake. The most likely problem is the pressure cap isn't hitting and seating on the washer like seat down in the bottom of the filler neck and letting water excape out the over flow if it comes off the neck. If the over flow comes off the top of the radiator tank the water is going out there and you need Skips 3 lb pressure valve on the bottom end of the over flow tube. The best way to test is not driveing but with a house fan AGAINST the grill running the engine at about 25 to 30 MPH speed. Fill the radiator up into the neck and take the temperatures with a laser thermometer every 5 minutes on the water outlets of the heads. What you see is what you will have under driving conditions, that is moveing down the road. Heavy slow traffic is where the hot conditions start do to the poor air flow from the fan. G.M.
 
Water when heated expands .If you are running a low pressure system it can benefit from a Little back pressure as it will dump up to 3 pints . On a high pressure system the cap should have a two way valve in it . If the system is working OK, after running the 5 miles home the water should be in the over flow tank when hot . After 5 miles running and cool down it should suck that water back into the radiator. A high concentration of coolant more than 50/50 x up to 100% can affect gaskets .
 
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36 ford said:
I'm running close to straight antifreeze, 7 lb cap, no smoke out the back and no evidence in the crankcase. I have an overflow tank which was about half full , went to a local car show about 5 miles away and there noticed the overflow tank was empty. radiator was full though. I've pulled the plugs and they look normal, too.

Phil
Click to expand...

Hey Phil,
IMO, FlatheadTed has it right! You've just explained that you don't have a 'problem', i.e.- no evidence/no smoke,etc..
You have described the way an overflow tank system works,eh! That is, it holds what fluid the heat EXPANSION chases out of the engine; then as engine cools down..causes vacuum (pressurized system) and sucks back into engine..ergo low/empty tank. Then cycle is endless without loosing fluid. Add fluid to keep tank half full and you should be good to go(if no evidence of leaks as you say).
 
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