Coolant issues maybe?

[Nitrofueled14]

I've got a 78 F250 with the 351M. When the engine gets hot enough and it shut it off I can hear the coolant bubbling in the radiator. The temp of the engine never gets too hot, it never overheats on long drives and doesn't ever loose power from getting too hot. It just doesn't get overly hot, but yet the coolant still bubbles in the radiator. Has anybody had this problem before, or know how to get rid of it?:mad3: The engine also runs perfectly fine.

[ImNotRight]

check the radiator cap, it may be getting weak, and spend some time trying to get any air out of the system.

[Nitrofueled14]

The cap is fine, it's still got plenty of spring pressure. So then what would be the best way to get air out of the system? I have a plug type thing on my heater core hoses that I can turn off, but no air comes out, just coolant.

[BrokeCuzWheelin]

I pretty sure that's normal. Your truck doesn't have a factory overflow bottle right? It just has the big ass down flow radiator? Try only filling to coolant so it is a couple of inches lower than the fillerneck.

[Nitrofueled14]

Yeah, thats the radiator that I have. I just made my own overflow tank which works very well.

[Coors]

I pretty sure that's normal. Your truck doesn't have a factory overflow bottle right? It just has the big ass down flow radiator? Try only filling to coolant so it is a couple of inches lower than the fillerneck.

Your pretty correct about that. My 78 will bubble over a little after I shut it off if the radiator is totally full. That is what an overflow bottle is suppost to do. Any car will flow over a little when it gets hot, and then suck a little back in as it cools.

As long as you have a good temp gauge that you know is working and that it is full of water and the thermostat is working, you should have no worries

[Nitrofueled14]

Yeah, everything works fine and it never gets too hot. I was just curious if the bubbling was bad or not. Thanks a lot guys.

[76HighBoy]

So then what would be the best way to get air out of the system? I have a plug type thing on my heater core hoses that I can turn off, but no air comes out, just coolant.

I have a cooling system tool that I use to get all of the air out of the cooling system. It’s called an "Airlift" and I purchased it from Matco when I was an automotive technician. It’s a two step process. 1st you attach it to your radiator and an air hose, and then suck all the air out of the cooling system. Once you reach a cretin vacuum reading, watch to see if the vacuum falls. If it holds, then your system has no leaks. If it falls, then you have a coolant leak. 2nd you back fill the cooling system from a bucket of coolant. This tool has saved me hours trying to get all of the air bubbles out of a cooling system.

[BrokeCuzWheelin]

I have a cooling system tool that I use to get all of the air out of the cooling system. It’s called an "Airlift" and I purchased it from Matco when I was an automotive technician. It’s a two step process. 1st you attach it to your radiator and an air hose, and then suck all the air out of the cooling system. Once you reach a cretin vacuum reading, watch to see if the vacuum falls. If it holds, then your system has no leaks. If it falls, then you have a coolant leak. 2nd you back fill the cooling system from a bucket of coolant. This tool has saved me hours trying to get all of the air bubbles out of a cooling system.

An Airlift is one of the best tools ever made. Saves lots of time.

nitro - Unless you have resently opened the cooling system up for some reason, you don't have any air in the system.

[Nitrofueled14]

Well I recently rebuilt the engine, then a little while after that I got a hole in my lower radiator hose because the belt touched it and cut a hole in it. I know it bubbled before the lower hose got a hole, and it still does it after.

[BrokeCuzWheelin]

If the truck isn't overheating I wouldn't worry about it.

[76HighBoy]

A friend of mine ahd a similar issue with his 351M in his 79 Bronco. He had the engine rebuilt, and the damn thing would sound like it was boiling inside the radiator. Come to find out one of his heads was cracked (machine shop missed it). He had a new set of heads rebuilt, put them on, and to this day has had no further boiling issue.

[chrono4]

exactly what i was thinking 76. take the cap off and stick your finger in it and rub around in there, does your finger have soot, or black shit on it? if so, this somtimes points towards a cracked head, or better just a head gasket.

[Nitrofueled14]

We just put new heads on the engine when we rebuilt it, so they better not be cracked... I'll check to see if there is any soot in the radiator.