Vacuum leak detection


I have a vacuum leak on the climate control somewhere in the car. would it do any damage pumping smoke pellet produced smoke through the system with an aquarium air pump, the a/c flaps all close when putting the pedal to the metal .
I have, over the years, changed the 1 way vac valve all the rigid pipe rubber joiners that are easily accessible with the cheek panels off and the radio out and all the feeds to silicone. but to no avail


Curious. This would be a no vacuum condition. Do your vents not move position when at idle?

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(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #3

That’s the usual symptom of a check valve that’s jammed open. The check valve is screwed into the intake manifold and provides the hose connection for the vacuum supply. It usually doesn’t require replacing, just take it out and fiddle with it until you get it unjammed and working right.

If there’s really a vacuum leak in the system, it usually causes an audible hiss. You can find it by just following the sound. That said, I dunno how your smoke plan would hurt anything.

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(scrimbo) #4

An old time mechanic showed me a quick vac. loss find method…take a spray can of carb. Cleaner and while engine is idling…spray around hose connections…if engine speeds up a little …there is a leak…what say anyone about that?

(Veekay) #5

I say, how does that help find a climate control vacuum leak?

(scrimbo) #6

Probably not effective as around engine hoses. …don’t know if the stuff could travel that far …anyway if you were leaking vac to a line that eventually went to climate control and it leaked near engine would that say something. …I don’t know but that test worked for me on other lines???

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found it, it was the vacuum switch, rtc670 (old exposed coil version) although still connected it had minute cracks in the plastic body were the pipe goes,
I joined the pipes together and perfect. can this be permanently bypassed?

(Andrew Waugh) #8

That test works fine when the leak is at the carbs/manifold, but there will be a time lag, and the idle will change less if your leak is much farther away.