interpretting leakdown test results

Got questions? We got answers....
Post Reply
bws2
Gold Member
Gold Member
Posts: 165
Joined: 09:30 pm Mar 15 2015
Country:

interpretting leakdown test results

Post by 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?
User avatar
KDXGarage
KDXRider.net
KDXRider.net
Posts: 14047
Joined: 06:45 am Nov 01 2004
Country: United States of America
Location: AL, USA
Contact:

Re: interpretting leakdown test results

Post by KDXGarage »

From what I have read, that is very good.
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
bws2
Gold Member
Gold Member
Posts: 165
Joined: 09:30 pm Mar 15 2015
Country:

Re: interpretting leakdown test results

Post by 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.
User avatar
Julien D
KDXRider.net
KDXRider.net
Posts: 5858
Joined: 07:53 pm Nov 07 2008
Country: USA
Contact:

Re: interpretting leakdown test results

Post by 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.
Image
John_S
Gold Member
Gold Member
Posts: 875
Joined: 06:59 am Jan 27 2017
Country: US
Location: Florida

Re: interpretting leakdown test results

Post by John_S »

Julien D wrote: 02:06 pm Mar 03 2019 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
Gold Member
Gold Member
Posts: 165
Joined: 09:30 pm Mar 15 2015
Country:

Re: interpretting leakdown test results

Post by bws2 »

John_S wrote: 08:37 am Mar 04 2019
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.
User avatar
Julien D
KDXRider.net
KDXRider.net
Posts: 5858
Joined: 07:53 pm Nov 07 2008
Country: USA
Contact:

Re: interpretting leakdown test results

Post by 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.
Image
Post Reply