Checking for a vacuum leak
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Senior User
Joined: Mar 2004
Posts: 146
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From: Norristown, PA
Checking for a vacuum leak
If I were to connect a vacuum gauge in line with the brake booster vacuum hose, what would the gauge read when idling assuming NO vacuum leaks? If there was a vacuum leak somewhere, then, what would the gauge read?
Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
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From: St Louis
Are you inline before the check valve? You should be at the engine vacuum pressure depending on how 'healthy' the engine is somewhere between 20 to 15 I think inHg. After the check valve the vacuum should be steady with the max observed engine vacuum, but I dont think you can be on that side of the check valve with out some fittings and more hoses.
Posting Guru
Joined: Nov 2004
Posts: 2,155
Likes: 1
From: sunny fla sometimes windy
It is hard to say like he said all motors will show a different vacumn, due to wear!!
Use propane cylinder torch (not lit) and pass it over your suspected leaks if it raises the rpms you found your leak!!! Don't buy just a vacum gauge go get one of those Mity vac pumps with the gauge they are great for bleeding brakes, checking vac,checking vac operated components,draining rearends without drains, power steering pump refills, I pull about a half a quart of my rangers tranny fluid every change with it just to make me feel better!!
Use propane cylinder torch (not lit) and pass it over your suspected leaks if it raises the rpms you found your leak!!! Don't buy just a vacum gauge go get one of those Mity vac pumps with the gauge they are great for bleeding brakes, checking vac,checking vac operated components,draining rearends without drains, power steering pump refills, I pull about a half a quart of my rangers tranny fluid every change with it just to make me feel better!!
Tuned
Joined: Aug 2005
Posts: 305
Likes: 1
Have you tried the propane trick before? I tried it today. I unhooked a vaccuum line at the "t" on the manifold and let the engine suck in some propane. I didnt see any diff in rpm. I also let it suck in some starting fluid and that rose the rpm but barely enough to be noticable. The fan was blowing and was loud so I could barely tell.
Posting Guru
Joined: Nov 2004
Posts: 2,155
Likes: 1
From: sunny fla sometimes windy
Yeah it has worked for me what kind of torch you got? Another good trick for propane torch is for starting your worn out weed eater if you got one that gives you crap starting, Open up the air cleaner and spray it in while cranking, I guarantee it will fire up!! Just don't run it on it without spraying in some oil too!!! And I meant to say I pull out the half quart of tranny fluid every OIL change!!
