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Using canned air to check vac leaks?


GtpKo
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Has anyone tried using canned air to check for vac leaks? I don't like the idea of spraying flammable liquid on a hot engine, so considering those air duster cans have a flammable warning on them, would it work for testing a vac leak?

 

I'm going to try in the next few days, seems safer than spraying TB or brake cleaner all over the place.

 

Has anyone tried it before?

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To check for vacuum leaks, you need a flammable substance. Blowing air on it isn't gonna do shit.

 

With a scantool connected, monitoring the fuel trims (which will be negative with a vacuum leak present) use propane directed through a hose so you can point/manuever it, go from spot to spot. If the engine changes load/running coniditon and the fuel trims go more positive, you found the spot/culprit of the vacuum leak.

 

Carb/choke cleaner also works.

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This is what I happen to have... yup its flammable!

p_00096.jpg

It has a red tube like cans of wd40 so I can pinpoint where I spray.

 

I don't have a scantool handy so I'll have to try and listen for a change in RPMs.

 

Reason I'm checking is that when I first started it up after replacing the MAF, I heard a definite whistle but I haven't heard it a 2nd time. I'm suspicious that might be just one reason why I keep getting a P0102+P0135+P0443.

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What's the difference between flammable liquid vs. flammable gas in terms of safety? You get careless, you have problems either way. I don't see the advantage to "canned flammable air".

 

I use aerosol carb spray. Propane "can" work, but it's not my first choice. Aerosol can is a one-hand, fingertip-precision deal. Propane takes two hands, (one to hold the pressure can, and one to wave the hose around) and it's a pain in the ass to turn on and off. I suppose that's fixable if you buy an expensive dispenser, but I don't own that tool.

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i use wd-40 when thats all i have, normaly use carb cleaner. (WD40 wont hurt any paint, etc.) and start spraying around suspected areas. When the WD40 hits a leak, th motor will stuble a bit if its a good size leak. it will also smoke out the exaust.

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Carb cleaner is awesome for finding vac leaks. So long as you're not spraying it directly on a hot exhaust manifold, you shouldn't have any issues. It'd be wise to have a fire extinguisher and/or water hose nearby just in case. I've diagnosed tons of vacuum leaks with carb spray and I've never had any mishaps with it.

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Carb cleaner is awesome for finding vac leaks. So long as you're not spraying it directly on a hot exhaust manifold, you shouldn't have any issues. It'd be wise to have a fire extinguisher and/or water hose nearby just in case. I've diagnosed tons of vacuum leaks with carb spray and I've never had any mishaps with it.

 

x2 on carb cleaner for finding vacuum leaks.

 

Just because its flammable doesn't mean it will set your entire engine bay ablaze.

 

That's like my mother in law who got mad at me for carrying a 3 gallon container of kerosene through the hallway of he house saying its dangerous. It was a moderately warm summer night. No fireplace, no heat, nothing, and she started freaking out. Flammable liquids and gasses require both quantity and an ignition source to cause any damage. Your little spritz of carb cleaner isn't going to do jack, even if you spray it right on the exhaust manifolds.

Edited by xtremerevolution
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So upon doing the actual vacuum leak check, I quickly figured out flammable air or gas or whatever wont work well outside when there's wind. I ended up using TB cleaner, found a small dry rot crack in the vacuum line, replaced all with ZZP's stuff and it's all good now. I hope.

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