interpretting leakdown test results

[bws2]

I did a leakdown test on my 2001 KDX 200 this afternoon.

I've never done one before and used a homemade tester that I put together.

I pressurized it to 5.5 lbs psi and it lost .75 lb over 10 minutes.

My question is is this an acceptable loss rate or does it indicate the engine has a problem that requires attention?

[KDXGarage]

From what I have read, that is very good.

[bws2]

I think I'll need to re-do the test.

I read last night that the piston should be at BDC.

I missed that step.

[Julien D]

I would think at BDC you'd be checking only for head gasket and rings, IE: top end leak. At or close to TDC will pressurize the crankcase and test the crank seals.

[John_S]

I would think at BDC you'd be checking only for head gasket and rings, IE: top end leak. At or close to TDC will pressurize the crankcase and test the crank seals.

I've always heard the opposite. It had something to do with the transfer ports not being blocked by the piston when the piston is at BDC.

Edit: Motion Pro's website says that the leakdown is done with the piston at BDC. It also says that 1psi per minute of loss is acceptable. I don't know about all that. If i pumped up an engine to 6psi and 6 minutes later it was at zero, I would fix the leak. If you retest and it barely loses any psi like your last test I would say its good to go.

I've also read but forget where that you should have your radiator cap removed during a leak down test to make sure no air is being pushed into the cooling system. Keeping the cap on could mask an issue.

[bws2]

I've always heard the opposite. It had something to do with the transfer ports not being blocked by the piston when the piston is at BDC.

Edit: Motion Pro's website says that the leakdown is done with the piston at BDC. It also says that 1psi per minute of loss is acceptable. I don't know about all that. If i pumped up an engine to 6psi and 6 minutes later it was at zero, I would fix the leak. If you retest and it barely loses any psi like your last test I would say its good to go.

I've also read but forget where that you should have your radiator cap removed during a leak down test to make sure no air is being pushed into the cooling system. Keeping the cap on could mask an issue.

Thank you, John. This is good information.

[Julien D]

Wasn't thinking of the transfer ports, as long as they are open when the test is run, then yes you are good.