The Ford Barn - View Single Post - Foaming coolant under heavy load, bad head gasket?

bavArian · 06-12-2022, 12:40 PM

Hello guys,

took my A for a longer trip today. Around 105 mls at ~30 °C / 90 °F weather. With my cooling problems I had to stop several times and generally go slowly, but we made it. I did notice however that as soon as I hit the gas hard (with the engine properly hot) the radiator almost immediately foams up.
A second after I step off the gas the foaming lessens considerably or even stops entirely. If I for example drive in 2nd gear with higher rpms without much gas/load that does not happen.
It also does NOT happen when the engine is colder, a minute or two after startup for example.

So it has to do with the pressure inside the cylinder. After arriving at home and letting the engine cool down a bit I removed the water pump belt, topped off the rad. and let the engine spin up from idle as fast as it can. (full throttle)
I could see one or two rather small bubbles (0,5 to 0,75 in diameter?) surface in the rad. neck around a second after each spin-up. Nothing when running at high rpms without load. In my opinion that points to a faulty head gasket.
BUT there's two things that slightly confuse me:
a) There is absolutely no white smoke coming from the exhaust or carb.
b) I have no measurable coolant loss when the car is sitting.

I did check the head nuts with 45 ft. lbs. (without loosening them up first) just to see if one of them is loose. (engine was still warm, about 45°C / 110 °F so I didn't want to use the 55 ft. lbs.)
None of the nuts were loose.

Tomorrow when the engine is cold I'll probably loosen and torque up each head nut in the proper order just to make sure it's not only a lack of torque.

From the symptoms I've described I guess that's only a really small leak? I've seen videos of faulty head gaskets, there's usually a lot of bubbles in the rad. neck even at normal or fast idle.
Could it be a crack in block or head or do the symptoms I've described usually point to a bad head gasket?

Does it make sense to try a sealant for the coolant like Bar's Leaks first or do these generally not work even with small leaks? Seems like opinions on these products differ, but nevertheless I'd like to hear them.

Thanks and have a nice day,

Daniel

06-12-2022, 12:40 PM	#1
bavArian Senior Member Join Date: Sep 2019 Location: Germany Posts: 221	Foaming coolant under heavy load, bad head gasket? Hello guys, took my A for a longer trip today. Around 105 mls at ~30 °C / 90 °F weather. With my cooling problems I had to stop several times and generally go slowly, but we made it. I did notice however that as soon as I hit the gas hard (with the engine properly hot) the radiator almost immediately foams up. A second after I step off the gas the foaming lessens considerably or even stops entirely. If I for example drive in 2nd gear with higher rpms without much gas/load that does not happen. It also does NOT happen when the engine is colder, a minute or two after startup for example. So it has to do with the pressure inside the cylinder. After arriving at home and letting the engine cool down a bit I removed the water pump belt, topped off the rad. and let the engine spin up from idle as fast as it can. (full throttle) I could see one or two rather small bubbles (0,5 to 0,75 in diameter?) surface in the rad. neck around a second after each spin-up. Nothing when running at high rpms without load. In my opinion that points to a faulty head gasket. BUT there's two things that slightly confuse me: a) There is absolutely no white smoke coming from the exhaust or carb. b) I have no measurable coolant loss when the car is sitting. I did check the head nuts with 45 ft. lbs. (without loosening them up first) just to see if one of them is loose. (engine was still warm, about 45°C / 110 °F so I didn't want to use the 55 ft. lbs.) None of the nuts were loose. Tomorrow when the engine is cold I'll probably loosen and torque up each head nut in the proper order just to make sure it's not only a lack of torque. From the symptoms I've described I guess that's only a really small leak? I've seen videos of faulty head gaskets, there's usually a lot of bubbles in the rad. neck even at normal or fast idle. Could it be a crack in block or head or do the symptoms I've described usually point to a bad head gasket? Does it make sense to try a sealant for the coolant like Bar's Leaks first or do these generally not work even with small leaks? Seems like opinions on these products differ, but nevertheless I'd like to hear them. Thanks and have a nice day, Daniel