Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Plugged Heater Core Test

Check to be sure the engine coolant is to the proper level, then start the engine and temporarily remove the outlet heater hose from the water pump. Very little or no flow of water from the core outlet indicates that the core or heater hose(s) is partially blocked or plugged.