Cigar test for vacuum leaks?

sublauxation

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Still hunting down my idle problem and came across a couple videos using a cigar to find vacuum leaks. Just put a rubber glove over the throttle body to plug it up, find an upstream vacuum hose and puff away. Anybody try this one? I don't know, maybe it's getting a bit desperate but what can it hurt?
 

GA_Boater

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I like an unlit propane torch myself. Open the valve and and run the nozzle around vacuum hoses and joints in the intake/throttle body on a running motor. When the motor speeds up, you found the leak.
 

sublauxation

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I can see where that would work better in most cases than the intake cleaner I used but it's barely idling and I don't think it's smooth enough to tell the difference.
 

bruceb58

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I like an unlit propane torch myself. Open the valve and and run the nozzle around vacuum hoses and joints in the intake/throttle body on a running motor. When the motor speeds up, you found the leak.
As long as you are working on a car and not a boat. I realize the OP is working on a car but since this is a boat forum, just wanted to point that out.
 
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GA_Boater

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As long as you are working on a car and not a boat. I realize the OP is working on a car but since this is a boat forum, just wanted to point that out.

I didn't and wouldn't advise the propane test for a boat. Plus it's in Non-Boating. And a boat motor doesn't have many vacuum lines, like none. :smile:
 
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bruceb58

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Yes, but you would be amazed what people will do. In another thread, a guy was asking about sucking the fuel out of an intake manifold with a shop vac.
 

Scott Danforth

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Yes, but you would be amazed what people will do. In another thread, a guy was asking about sucking the fuel out of an intake manifold with a shop vac.

darwin would have taken care of that quickly
 

Boomyal

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What's the problem with using propane on a boat motor running in the driveway with the doghouse removed? I just did it on mine, trying to identify the reason for an inconsistent idle situation. btw, no leaks were found anywhere around the carb base or throttle plate shafts.
 

bruceb58

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What's the problem with using propane on a boat motor running in the driveway with the doghouse removed? I just did it on mine, trying to identify the reason for an inconsistent idle situation. btw, no leaks were found anywhere around the carb base or throttle plate shafts.
becuase propane sinks into your bilge.
 

bruceb58

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No bigee. Bilge plug is out and there is a lot of air circulation.

LOL...I would not be counting on the bilge plug to vent the propane very fast.

I have a water heater that runs off propane. I thought I had plenty of ventilation. Propane built up behind a ledge that was only around 4" tall. I was lucky when it exploded that I didn't get hurt.
 

JustJason

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I can see where that would work better in most cases than the intake cleaner I used but it's barely idling and I don't think it's smooth enough to tell the difference.


If you had a vacuum lead the engine would have a high idle condition. Not a barely idling condition.
 

bruceb58

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Depends on how bad the vacuum leak is. Most fuel injected automotive engines are more on the lean side at idle already. Making it more lean doesn't help the idle. Marine engines would be a different story.
 
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