Happened yesterday and just this morning, my standard style radiator has been puking on my flathead v8. Driving 45 mph
I noticed fluid drops on my windshield, and on the side flip out vent windows
Pull over and the front grill full of fluid (about 1 cup).

Lift the hood, looks like the above the pressure cap must have had a blow out,
there was fluid under hood right above cap.

I checked the fluid level in radiator again just before driving it this morning.
Fluid was JUST over fins.

I have 2 mechanical temperature gauges , 180 stats, and teh temp NEVER went over 180.
I can't figure out what's going on.

 

i'd be wiling to bet , and i know this from experience , you got a head gasket[s] starting to seep / leak . my flatty did it to me .

 

Motor was just rebuilt, head gaskets new, and has less than 400 miles on it. Think I need to retorque headbolts?

 

Retorque the head bolts - which is a good idea after 400 miles. 65-70 ft/lbs on stock iron heads. 50-55 ft/lbs on aluminum aftermarket heads. Check them again after another few hundred miles.

Also leave the coolant level where it stopped. Just above the tubes. 5 gallons of coolant expand a bit and mine will puke it out until it reaches that point of equilibrium and then it stays there. You just overfilled it.

 

check your rad. cap to be sure it's seating and the gasket is good. If it has been replaced it could be the wrong one and if'so it might not be actually seating on the neck.
If you run your radiator low to prevent the over flow you will have less coolant to keep your engine cool.
Good luck
Larry

 

just a stupid reminder too as most dont think of it .... are old flatties and radiators only take a 4 pound cap . i grabbed one off my bench slapped it on and a little whil later popped a seem on the radiator ............ yeah retorque 'em . i must've retorqued / checked mine every time i serviced it . these old things are kinda cranky sometimes............

 

I have been dealing with that for 40 years. A 1950 F6, a Trojan Loader,
and a 1978 F150 imagine that- three vehicles with the same symptons.
On these three a gallon jug is a must. Heres what happens the temp
goes up to about 200* when thermotats open they berp into the jug
then they settle down to 180* then I pour the jug back into the radiator.
They have been pressure tested, tested with dye no issues, no head
gasket problems, but one sympton I notice is they do not throw heat
(the heaters) until the thermotats open. To me thats saying there is
a air bubble causing this BUT, I can see one doing this but not all three
acting the same way, being a 239V8 6cyl IH in the loader and a 302 in
the 78. A pain im use to (open hood start vehicles wait till they burp,
pour coolant back in rad close hood good to go UNTIL tomorrow) then
do it all over again.?????????