[AT] propane to detect vacuum leaks.

[Phil Auten]

Yup.

Phil in TX


On 10/29/2019 11:13 AM, Stephen Offiler wrote:
> If you need the information provided in Step 1, just close the hood 
> and walk away.
>
> SO
>
> On Tue, Oct 29, 2019 at 12:04 PM James Peck <jamesgpeck at hotmail.com 
> <mailto:jamesgpeck at hotmail.com>> wrote:
>
>     Here is a post outlining the procedure for vacuum leak testing
>     with propane.
>
>     https://www.hunker.com/13414896/how-to-find-a-vacuum-leak-with-propane
>
>     48 years ago a man taught me how to use a vacuum gauge in
>     diagnosing a blown head gasket.
>
>     I will have to remember Stephens tip for using propane on hard
>     starting gasoline engines.
>
>     [Jack] If a bare plug wire were sparking to ground it could light
>     the propane torch if you moved the torch nozzle so propane flowed
>     over the spark. A bare plug wire itself would not heat propane to
>     its ignition point.  The torch itself restricts the propane flow.
>
>     However, the only engines I have encountered with hard to find
>     engine vacuum leaks are V6 and V8s where the intake manifold seals
>     against both the block and heads. You can’t usually see the rear
>     manifold seals and they do get out of place. Tractor spark ignited
>     engines are generally straight 4s and 6s.  I suspect that the use
>     of propane to find vacuum leaks dates to the introduction of the
>     OHV (overhead valve) V8.
>
>     We did have a flathead Ford V8 on a piece of equipment when I was
>     a kid.
>
>     I once had a pinhole leak in an anti-dieseling pneumatic damper
>     diaphragm that I found using a handheld vacuum device. This was on
>     a vehicle without ECM (engine control module).
>
>     [Jim Becker] I’ve wondered how often that method accidentally
>     finds a plug wire with bad insulation.
>
>     [Jack] In the automotive courses I took, we would use an unlit
>     propane torch and direct the gas flow over spark ignited engine
>     areas of possible vacuum leaks. If the engine speed increased, you
>     had found the leak.
>
>     [Stephen Offiler] Anybody use propane/MAPP?  Unlit torch pointing
>     into the air box.  I use it on reluctant gasoline engines with a
>     fair amount of success, but not so sure about diesel.  Since we're
>     talking about gas-soaked rags or gas-soaked air filters on diesel
>     engines, seems like a similar approach.
>
>     .
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