70 c10 overflow bubbling

[mhoneycutt85]

Hey everyone,

As stated above, my c-10 is overheating and seems to have trouble releasing pressure. I have an overflow tank on the truck, but after taking the truck down the road for a while and upon parking I hear bubbling and the radiator is spewing into the overflow tank. The overflow tank I have is one with the snap top cap so it has enough pressure after a minute or so to actually pop the top. My first thought was the thermostat, but I replaced that and while the truck is running I can see the water moving in the radiator. My temp gauge is very intermittent and sometimes will peg itself and then brings itself back to a normal reading. No water in the oil so far and no white smoke. The truck runs strong and doesn't want to cut off once it "reads" hot. I am really concerned about this overflow issue as I can feel an enormous amount of pressure on the top radiator hose. Any suggestions or things I should check before taking on the worst case scenario projects?

[5150.4.67]

2 reasons engine puke water.
1.) Over heating
2.) Combustion pressure entering the cooling system (head gasket failure or cylinder head cracked.)

Or both........

Make sure the thermostat is opening and its full of water. If the top hose gets hot, the thermostat is opening.

[5150.4.67]

A cooling system has a few challenges. Water works good to remove heat. But it freezes. Enter antifreeze. Problem solved.
Water boils at 212 degrees. Enter the radiator cap. The higher the pressure, the higher the boiling point. Your cooling system should be under pressure when hot. A radiator cap typically holds 15 pounds of pressure, which translates into a higher boiling point.... around 45 degrees higher, or 255 degrees. When it exceeds that pressure, it blows it out into the overflow tank.
Whats that mean? It is either very very hot, or the radiator cap is not holding pressure......
Check your cap next, since you already changed the stat.
I'm not feeling confident this is going to have a good ending........
Good luck, let us know what you find.

[mhoneycutt85]

I appreciate you taking the time to answer my question. I too feel that it is in fact the worst case scenario. I'm going to replace the cap and we will see what happens. I will let you know what I come up with.

Mike

[geezer#99]

How high do you fill the rad before you put the cap on??

[mhoneycutt85]

Originally Posted by geezer#99

How high do you fill the rad before you put the cap on??

I fill the radiator up almost to the top but before the port to release into the overflow.

[geezer#99]

Fill it up like you would if you didn't have an overflow. Like about 1.5 to 2 inches down in the rad. See what that does.

[mhoneycutt85]

Originally Posted by geezer#99

Fill it up like you would if you didn't have an overflow. Like about 1.5 to 2 inches down in the rad. See what that does.

Alright, I will try that. Thanks.

[geezer#99]

One more thought. Your overflow tube that goes into your sealed overflow bottle. Is the end of the hose submerged close to the bottom?

[mhoneycutt85]

Originally Posted by geezer#99

One more thought. Your overflow tube that goes into your sealed overflow bottle. Is the end of the hose submerged close to the bottom?

Yes. Below is a link to the one i have.

http://www.drivewire.com/images/shop...cs/idymcr3.jpg

[5150.4.67]

If you fill it to the top, it won't matter. Once it heats up and expands it will push it out the into the overflow as its designed to do. Let us know how it goes.....

[bighaas79]

If the upper hose is getting hard from pressure while running its cause you are dumping exhaust gasses into the cooling system. like was said before you have head gasket or cracked head. You can monkey around with the level in the rad. or the overflow all ya want it isn't gonna make up for the main issue.

[mhoneycutt85]

Originally Posted by bighaas79

If the upper hose is getting hard from pressure while running its cause you are dumping exhaust gasses into the cooling system. like was said before you have head gasket or cracked head. You can monkey around with the level in the rad. or the overflow all ya want it isn't gonna make up for the main issue.

So today I bought a new radiator cap and no more issues. I am ecstatic to say the least.

[5150.4.67]

Quick, go buy a lottery ticket!

The most happiness one can buy for less than 10 bucks.............

[Longhorn Man]

no need for a lottery ticket... it was a simple problem with a simple fix.