The Stovebolt Site Forums The Shop Area Engine Shop No Radiator Puke! FINALLY!

I've been battling this for months. After getting my truck back on the road I couldn't figure out why my radiator keeps blowing steam everytime I drive it. I've tried everything! And spent lots of money.
As a last resort, I installed an aftermarket temperture guage under the dash (temporary) to verify that my truck wasn't running hot. On a 100 degree day, my 216 motor never got above 195, yet it still boils over and blows steam.....big time. I took the radiator back out again and had it checked out at the radiator shop....again. He said it was fine, so I told him to plug off the vent tube on the top of the top tank. I also had him replace the original (no pressure) fill spout with a new style fill spout so I can use a pressurized radiator cap. I put everything back together and installed a 7 pound cap. Guess what? NO PUKE! NO MORE! I can now cruise all day long with no worries. Should I go with a lower pressure cap?

Why would you plug the vent tube? Where do you expect the water to go when it heats up and expands? Where do you think it will go? It has 2 places to go, out the cap or thru the head gasket into the combution chamber. Your solution make no sense to me. The vent tube is there for a reason. If your arm was broken would you have the doctor cut it off? You haven't solved the problem you have eliminated the symptoms. You may be satisfied with your solution but it will manifest itself into other problems down the road.

I may be wrong but I believe that for every pound of preasure that you add to a system it increases the temp by 3 degree. So your 7 lbs cap will raise that 195 to 216. So I would recomend 2 things go with the 0lbs cap and put in a 180 or lower thermastat.

Sorry to rain on your parade. All I can say is enjoy your truck while it is running fine.

Brian is correct. Fluid cannot be pressurized like a gas. As the temperature of liquid rises, the liquid expands. If there is no place for the liquid to expand, it forces is own place, ie. the head gasket, radiator hose, radiator, radiator cap. You MUST have a way to relieve the expansion of the coolant, or something is going to give!

Good luck,
Phil

John - I did the same thing on my 46. It works fine, just don"t go over a 7 lb cap. I was told by my radiator man that the seams in the old radiators won't take any more than that. If you are worried about it you can go to a 4lb cap.

Brian & Phil I think you misunderstood what he has done. there is a overflow/vent built into the modern filler neck. It just dosen't allow the low pressure to push the water out like it does with the old non-pressurized system. Once the pressure reaches the rating in the cap it is released, just like on a modern truck. You can even install an overflow tank and any fulid pushed out will be recycled.

John, glad you got your problem whipped

George

Thanks for the vote of confidence George. I don't see what the big deal is. If the coolant needs to go somewhere, it can go out the overflow tube in the filler neck into my newly installed overflow tank. It's no difference than any newer radiators.

John,

Another battle won! How many left?

I hope to take my first "real" drive tonight. Truck needs gas, so I figure that will make a good first trip.

Trip number two will be to the muffler shop for a new exhaust system.

John from MN

Maybe people were confused because you forgot to mention you put in another overflow tube. When I read your post I thought: "Kaboom!" Also, won't your current setup not start puking until 7lbs of pressure is reached? That is 7lbs higher than the system was designed for.