I can't seem to find anyone that knows for sure what the difference is between a vented and non-vented radiator cap.

I've heard a lot of guesses, but I need to know for sure. Is the stock Honda radiator cap on my 1990 Civic vented or not?

 

Still no luck, and I've been searching all morning.

 

nope cuz i have the same one and sometimes i get pressure in there/ you can hear when i open the cap it lets all the air out...............

Does Your Cap Have A Little Red Handle On The Top?

 

there is NO such thing as a vented radiator cap, thats why you cant find anyone that knows anything about it. if you mean a relief valve then yes, some aftermarket caps have them built in just to relieve system pressure before removing the cap.

think about how a cooling system works, it relys on pressure in the system, once that pressure is exceeded the coolant boils and the cap lets the excess pressure into the overflow tank. w/out pressure in the cooling system the boiling point of the system would be decreased dramatically, which is why a leaking radiator cap causes problem.

hope that helps.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jeezyskillz &raquo;</TD></TR><TR><TD CLASS="quote">
Does Your Cap Have A Little Red Handle On The Top?</TD></TR></TABLE>

"vented" is different from what you are talking about here. There are caps that have a special lever that is used to release the pressure before taking the cap off, that's different from what I'm talking about.

Check this out: http://www.stant.com/brochure....d=179

Compare these two part numbers for example:

- 10331, "16lbs. Vented. For radiator overflow reservior systems"
- 10330, "16lbs. For radiator overflow reservior systems"

Both of the above examples have a pressure release lever and look like this:



Yet one is vented and the other is NOT. What's the difference?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by schardbody &raquo;</TD></TR><TR><TD CLASS="quote">there is NO such thing as a vented radiator cap, thats why you cant find anyone that knows anything about it. if you mean a relief valve then yes, some aftermarket caps have them built in just to relieve system pressure before removing the cap.</TD></TR></TABLE>

See the above listed link. It clearly shows two part numbers, one is 16lbs vented, and one is just 16lbs.

I've called a few auto parts stores and the guys I talked to said the same thing. "There's no such thing as a vented radiator cap".

That's why I'm on here trying to find someone who knows.

 

yeah, if you consider it the way they do i guess, a system that uses an overflow *ie: alot of GM front drive cars* where the radiator fill is in the overflow tank, the cap is completely sealed. thats what the differance is, USE A VENTED CAP for sure.