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Old 05-06-2008, 11:55 AM   #22
Scooby Specialist
Member#: 26770
Join Date: Oct 2002
Chapter/Region: South East
Location: Tampa
'02 WRX
midnight black


I don't THINK both caps are the same. I would ASSUME the lower pressure cap would be on the coolant reseviour (highest point) for coolant/air movement to the coolant expansion tank. I'm pretty sure the 2 caps have different PSI/BAR ratings.


STi rating (18 PSI):

WRX low PSI cap @ high point location = 16 PSI:

Unibombers Coolant FAQ:

..."CAUTION The new system is provided with two different caps, one on the radiator and one on the pressurized tank as shown in the above table. Accordingly, pay special attention not to mix up those caps. If they are switched, it could cause overheating which may lead to engine failure. "...

Cap w/ ears go on the highpoint (vac & pressure relief), and round cap on radiator (only over pressure relief).
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Last edited by strohausii; 10-06-2008 at 08:32 AM. Reason: summation
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