Correct way to check for engine leakdown?

[Chuckie02Shee]

I finally got the Shee engine back together. Cylinders measured out good enough for a light hone and new rings on factory pistons(64mm). All new seals and replaced all o rings in the cool-head,and replaced all gaskets. I went to check for leakage,I was told to put 6psi of air pressure into engine and should hold that for 6 minutes.I put 6psi of air pressure in engine and it leaked off 2 psi in 6 minutes!! Is there a certain list of protocol to do a leak down check or is there something wrong with the engine,and will it still run like this?

All feedback is welcome.

Thanks in advance

[mhoksch]

When I did mine I wasn't satisfied until i only lost 1 psi over 30min. Maybe I'm just picky...

 

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[Strm Trpr]

Repressurize it and spray soapy water to check for bubbles on all case seams, external crank seals, reed cages to cylinders, intakes to reeds, cross-over tube fittings, sparkplug threads and of course the components used for the leakdown test that are attached to the intakes and exhaust including the fitting used to pressurize the engine.

[Starwriter]

^what he said, and the PTO side crank keyway.

[Strm Trpr]

And the PTO side crank keyway.

I haven't been that deep into a Banshee motor yet, but shouldn't any keyway be outboard of the seal?

How do you fix that, a little RTV?

[Starwriter]

It's very common to leak at the keyway if you don't seal it with some sealer during assembly. This is why, on a new build, you should always do a leakdown test before you put the clutch cover on.

 

 

[Strm Trpr]

OIC, excellent.

Thanks for the tip!

[Jereme6655]

as these guys have said....soapy water and check all the areas that leaking is possible.  technically you can leak off 1psi per minute and still run it.  However I do not let my motor out of my shop unless it is leaking less than 1psi in over 15 minute time span. 

 

That being said.....there are a few places that these guys have mentioned about that tend to leak more than others.  Every motor is different so keep that in mind when your doing your leakdown test.  For instance.....my motor tends to like to leak between the reed cage and the cylinder.....to the point that I have to use a little dab of case sealer to aid in sealing it. However I've never had to seal the keyway on my cranks.   ALSO the crush washers on the spark plugs can bite you in the ass. 

[Chuckie02Shee]

Finally got the time to reply with results(WORK SUCKS!!!) I went back over my engine with Windex and found that both the spark plugs were leaking and both the VForce 3 reed cages to be leaking also. After what seemed to be tightening the F*** out of both issues I'm still leaking off about a half lb of PSI in 6 minutes. Before it was a lot more There were no other leaks including the PTO key-way seal. Is this acceptable to put in the frame and BRRAAAPPPPP ?!!!

[Jereme6655]

run it.

[Starwriter]

Although 1/2 pound in 6 minutes is perfectly acceptable, I wouldn't be happy with any amount of intake gasket leak. I would pull them and seal them with 1211, let it dry over night and retest.

[trickedcarbine]

Spark plug leak... Eh not to big a deal. Run em in with some anti seize once and they should be cool.

 

The intake leak though, those cost people lots of dollars. I'd pull the cages and put a thin coat of 1211 case sealer, fuel safe RTV, or Toyota gasket sealer.