Higher pressure rad cap?
Discussion
The Radical supplied one is rated at 1.1 bar, after racing I generally have 300/400ml of expanded coolant let out by the rad cap into the overflow container which I then have to pour back in after its all cooled back down again.
a) Is a higher rated cap of 1.5-1.6 bar going to help this problem?
B) Likely to cause any other issues at all?
a) Is a higher rated cap of 1.5-1.6 bar going to help this problem?
B) Likely to cause any other issues at all?
Do you have enough air volume in the system? Ideally you'd have at least a liter, this provides some 'spring' in the system which helps stabilise the pressure. If the overflow is designed properly, the system should draw the expelled water back in after it has cooled right down. It probably won't be cool enough to do that within a couple of hours. Bear in mind that if you release the pressure cap and hence release all the pressure while the system is hot, it may take a considerable time to build pressure back up, and you can damage things if you drive it hard in the meantime. Best leave the cap alone until it's completely cooled down.
Green,
I don't know the volume of air in the system, but next to bugger all I would of said?
The system only has a very small swirl pot that maybe has of a total volume of approx 500ml for both the fluid & air to share? This is sited at the highest point in the system & is linked to the top of the radiator via a very short hose, hopefully the expansion tank idea as per Simons installation will do the trick by proving extra capacity.
What level of fluid would you normally run in the swirl pot when filling a cold system? I maybe bringing the coolant loss problem upon myself by overfilling the swirl pot as I normally fill it to about 30mm from the top when the system is stone cold?
Its always struck me as a little short on coolant capacity as a supplied system for Radical to be honest, with what I think is around 3ltrs total capacity?
I don't know the volume of air in the system, but next to bugger all I would of said?
The system only has a very small swirl pot that maybe has of a total volume of approx 500ml for both the fluid & air to share? This is sited at the highest point in the system & is linked to the top of the radiator via a very short hose, hopefully the expansion tank idea as per Simons installation will do the trick by proving extra capacity.
What level of fluid would you normally run in the swirl pot when filling a cold system? I maybe bringing the coolant loss problem upon myself by overfilling the swirl pot as I normally fill it to about 30mm from the top when the system is stone cold?
Its always struck me as a little short on coolant capacity as a supplied system for Radical to be honest, with what I think is around 3ltrs total capacity?
How does the header tank to overflow tank mechanism work?
Presumably coolant has to blow past the pressure cap into the overflow tank. I assume the overflow tank is not pressurised? Then how does the coolant get past the pressure cap back into the header tank? Is it a specific type of cap for this kind of system? Is there a one-way valve for the coolant to go back through?
So many questions!
Bert
Presumably coolant has to blow past the pressure cap into the overflow tank. I assume the overflow tank is not pressurised? Then how does the coolant get past the pressure cap back into the header tank? Is it a specific type of cap for this kind of system? Is there a one-way valve for the coolant to go back through?
So many questions!
Bert
As the pressure builds it forces the sprung rad cap seal upwards allowing the coolant to flow into the expansion tank. As the coolant cools and the pressure drops the vacuum/atmospheric pressure forces the coolant back into the header tank. As the pressure drops further the rad cap spring overcomes the coolant pressure and closes the seal.
Simon
Simon
Edited by Simon T on Thursday 30th July 23:02
Simon T said:
As the pressure builds it forces the sprung rad cap seal upwards allowing the coolant to flow into the expansion tank. As the coolant cools and the pressure drops the vacuum/atmospheric pressure forces the coolant back into the header tank. As the pressure drops further the rad cap spring overcomes the coolant pressure and closes the seal.
Simon
Now that's what I can't get my head around if the overflow tank is open to the air. Coolant will be momentarily vented when the engine gets hot until the pressure in the hot engine drops and the cap spring seals the cap again. It doesn't/cant stay open until the engine cools to suck the coolant back in.Simon
Edited by Simon T on Thursday 30th July 23:02
Bert
All I know is it works...BertBert said:
I'm just inrtigued as I can't work it out!!! I can't see how coolant gets sucked back in without a valve. I'll mooch round the Bert fleet this afternoon and see if any have a header tank/overflow arrangement to look for clues!
Bert
I'd guess because the 'overflow tank' is actually a 'closed to air' 'expansion tank' and that it's the header tank that is vented to air, but let us know after you've done mooching.Bert
BertBert said:
wikipedia said:
When the coolant cools and contracts (as conditions change or when the engine is switched off) the fluid is returned to the radiator through additional valving in the cap.
Phew, feel much better now. Is there something wrong with me in the heeeeed?Bert
perhaps the problems with the leeeeeg have spread to the heeeeed?Gassing Station | Radical | Top of Page | What's New | My Stuff