Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Cracked Head Leaking Head Gasket?
View Single Post
  #14 (permalink)  
Old 02-17-2013, 07:12 PM
Northern Chevy Northern Chevy is offline
Registered User
Join Date: Feb 2013
Posts: 91
Wiki Edits: 0

Thanks: 0
Thanked 12 Times in 12 Posts
Just to clarify, have you been doing this a few times now in trying to add coolant by removal of the cap from the hot engine while its running { which is very dangerous in itself for being horribly burned }, then shutting the engine down ? If so, that coolant "launch" as you put it when an engine is shut down, is exactly what will happen with a properly operating engine. Once the coolant flow is stopped by the water pump not circulating it, it will super heat by a hot engine and boil and just come frothing out violently.

The only way I know to add coolant to a mechanically sound { not leaking or head gasket failing } engine so that you don't reintroduce air pockets from super heating coolant by releasing the pressure is to NOT touch that rad cap when the engine is up to operating temperature and just make sure you have plenty of coolant in the overflow reservoir and let it self siphon into the engine as it cools. Then after many hours of cooling, its ok to remove the cap and see if there is an air space left and if so, top it up and squeezing and releasing the top rad hose can aid in working out a little air ... its slightly helpful I find sometimes. The heating and cooling cycles of the engine are typically what is used to completely fill an engine so there are no pockets of air in the heads as its that air which will cause a lack of heat transfer and the engine will run hotter and can damage it if it gets out of hand.

Also its not really recommended to mix coolant that strong unless you live in a VERY cold climate where the coolant will jell in the rad by supper cooling as a 50/50 mixture is generally ideal as a balance between boil over and cold temperatures and the reason being, too high a coolant concentration does not transfer heat away from the engine or reject it out of the rad by air flow as well. Sometimes more is not better and that happens to be the quirk of antifreeze. Water is the better heat transfer agent but it has too low of a boil point and no rust inhibiting properties or ability to lubricate the water pump seal.

Please don't think I am coming across as anything other then wanting you to stay safe, and pointing out there is a reason why a rad cap is designed to build that pressure which is, to keep the boiling point of the coolant at a higher temperature ... as soon as you remove that cap, the boiling point drops below the actual temperature of the engine and you saw the results of that with coolant spraying your nice clean engine compartment with slime everywhere !.

Hmm, hope that came across as intented !.
Reply With Quote
The Following User Says Thank You to Northern Chevy For This Useful Post:
skippy89 (02-17-2013)