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)

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Component Tests and General Diagnostics


1. Run engine at normal operating temperature and set throttle on high cam on 4-140 engine or on kickdown step on other engines.
2. Connect vacuum gauge to EGR side of load control valve and note reading.
3. Apply a vacuum of at least 6 inches Hg to venturi port of valve. If gauge does not drop to zero, replace valve.