The V8 Owners Forum -

Guys any tips for diagnosing an air leak, ive double checked all the usall suspects hoses, stepper motor, plenum seating, butterfly alignment, throttle linkage (no hang up), throttle pot and im drawing a blank.

I changed the valley gasket and injectors a little while back, possible causes?

Have i answered my own question or can you throw any other ideas in the pot.

Thanks in advance

O rings on the injectors?

Hi
Have you tried running it at idle and having a squirt around suspect areas with a tin of WD40 or damp start, when you find the spot the engine revs will rise and you can then investigate further.
Best regards
Mike

Hello Moose. If you were relying on visual checks there are quite a few things to miss, mainly the innards of other components. Therefor one needs to apply a dynamic test process. It does rely on the ability of the engine to run at idle speed tho'. Read the PDF available here for the full nine yards.

http://www.vintagemodelairplane.com/pag ... num01.html

In addition there are some airleak events that defy interrogation.

# Invisible splits in the AFM to Plenum tunnel hose can be eliminated by wrapping the hose with domestic cling wrap and securing with duct tape.

# If a twin plenum, there is a large O ring required at the AFM/Branch pipe joint.

# Incomplete rocker gasket seal will allow air into the crankcase ventilation system and thus unto the plenum via the breather hose, by default.

# If the hot spot has been removed from the plenum tunnel area, the fixing holes muxt be sealed or they can leak directly into the tunnel.

Thanks for the ideas chaps.