Radiator cap Leak Question

[EsperHamid]

is it normal when climbing a really steep hill in a CB7 that little coolant will seep out of the radiator cap ?!

1) My radiator is NEW

2) This doesn't happen in city driving !!

Do I need to replace the cap or is it air inside the cooling system ?!

[illinois_erik]

is it normal when climbing a really steep hill in a CB7 that little coolant will seep out of the radiator cap ?!

1) My radiator is NEW

2) This doesn't happen in city driving !!

Do I need to replace the cap or is it air inside the cooling system ?!

its a pressurized system, so id say no.

[Kev1990]

I wouldn't say it's normal. My radiator cap started leaking a few months ago just very little through the cap no matter what the driving conditions. I put Teflon tape around the neck of the radiator it fixed my problem no more leaking I even put a new cap on and it still leaked. I could see where a little tiny chip of the radiator neck was missing though on mine. If you wrap Teflon tape around it and it still leaks try a few more wraps around it and it should stop the leak LOL at least for me it did haven't had a problem since and I was gonna throw a new radiator in so I would try that lol.

[Fleetw00d]

its a pressurized system, so id say no.

Which of his three questions are you answering as "no"?

is it normal when climbing a really steep hill in a CB7 that little coolant will seep out of the radiator cap ?!

1) My radiator is NEW

2) This doesn't happen in city driving !!

Do I need to replace the cap or is it air inside the cooling system ?!

Coolant should not leak out of the radiator cap. The cap should seal such that when the system heats up and pressurizes, the pressure, whether caused by expanding air and/or coolant, is relieved to the overflow tank.

Do you need to replaced the cap? Did you replace the cap with the radiator? Check the surface where the cap seal contacts the radiator for damage. Check the sealing surfaces on the cap for damage or that the seal itself has hardened or taken a set; if there is replace it.

Is it air in the cooling system? The seal on the cap should prevent both air and coolant from leaking externally. As above, pressure in the system is intended to be relieved to the overflow tank. If there is air in the system, as it heats up and expands, it gets pushed to the overflow tank; then when the system cools, the pressure drops below atmospheric and coolant from the bottom of the overflow tank is pushed back into the radiator to keep the system completely full of coolant.

[illinois_erik]

Which of his three questions are you answering as "no"?

The first and important one. The second answer can be concluded based off the first questions answer depending on how he wants to remedy it. there wasnt a third.

[EsperHamid]

Thank you guys for your answers, I conclude that I should replace the cap. The radiator is newly replaced but the cap is still the old one and it has a 0.9 c19 marked on it.

should I get a new 0.9 or 1.1 cap ?

My suggestion about air in the system, means that if some air is getting in from old hoses, it might push some coolant out of the cap

but since FleetW00d explained it, I concluded that the cap needs to be replaced

Thank you

[illinois_erik]

Thank you guys for your answers, I conclude that I should replace the cap. The radiator is newly replaced but the cap is still the old one and it has a 0.9 c19 marked on it.

should I get a new 0.9 or 1.1 cap ?

My suggestion about air in the system, means that if some air is getting in from old hoses, it might push some coolant out of the cap

but since FleetW00d explained it, I concluded that the cap needs to be replaced

Thank you

youre welcome, all my cars have had a 1.1 bar cap.

[EsperHamid]

Thank you Erik

[johnl]

Needs a new cap, fit it and cross your fingers. There should be no leak at that point even if the system were to be over pressuring (any 'excess' coolant or gas should all end up in the overflow tank if the cap isn't leaking).

However it is a little unusual that it only leaked when "climbing a really steep hill", because a leak at the cap (i.e. a faulty cap) would I think occur each time the engine approached normal operating temperature (some coolant is always expelled, then 'retrieved' as the engine cools down).

Climbing a hill is not unlikely to cause a higher than usual temperature, and perhaps expel coolant into the overflow tank more forcefully (especially if there was any localised boiling in the water jacket), so a cap leak may be more obvious in that circumstance. Hopefully it's nothing worse, but I'd keep an eye on it for a while...