leak down test rig

[matt glascock]

Hey all, I've been fiddling with designing a system to simplify performing engine leak down testing. Basically, it involves sealing intake and exhaust and pressurizing the engine with the piston BDC through the transfer ports using an adapted hose from a compression tester that threads to the spark plug hole. Does anyone do this or is this a dumb idea? If I'm barking up the wrong tree here I will abort and go back to the tried-and-true.

[hodakamax]

Hey Matt, for what it's worth, here's a quick thing I whipped together in an emergency a few months ago. I had to scrounge everything from the shop as it was Sunday and they had rolled up all the sidewalks in town. I plugged the exhaust with a rubber ball and the exhaust nut. I made the intake plate from 1/8'' aluminum positioning an inner tube stem for pressurization with my airbrush regulator set at about 6#. The port for the gauge was from a disassembled cable TV fitting. Most of the leaks were in the apparatus but finally I did a successful leak down test with what I had. Whatever works, I'm sure yours will be more sophisticated than my device. It should work, Good luck!

Max

[matt glascock]

Very clever, Max. That looks more dependable than what I'm working with. The Achilles heel seems to be the air line fitting from the compression test line to the air line gauge. At 6 PSI there is not enough pressure in the system to get a good seal at that connection. I'll keep tinkering with it. Thanks, Max!

Best,

Matt

[relic]

I've done the test both ways. At work we have some adapters made up or supplied by the manufactures (Stilh for instance for chainsaws/trimmers etc) that bolt on in place of the carb. But as you can see in the photo, I've also adapted to one of my snap on compression test leads. Remember to remove the valve core.

Testing one cylinder of my Suzuki GT500B a few years back.

Ken

[matt glascock]

Slick Ken! Is there a t-connector hidden in your hand? Also which valve core are you referring to? Many thanks!

Matt

[relic]

Slick Ken! Is there a t-connector hidden in your hand? Also which valve core are you referring to? Many thanks!

Matt

Yes Matt there is a T in the line. The valve core is at the threaded end of the compression tester hose. Some tool makers put the valve core somewhere at the gauge but the snap on ones have it at the end. I made up this tester from an old blood pressure tester, some hose and the t fitting is from a windshield washer kit. I also use this set up for testing carb inlet needle/seat for leakage.

Ken

[matt glascock]

Oh, I see. The Schrader-type air check valve like on a tire valve stem needs to be removed. Very crafty rig you've designed. I've been mooching a slick prefab leakdown test kit from one of my riding partners for years and felt it was time to reverse engineer one of my own. Between the suggestions from you and Max, I think I can come up with a slick rig. I'm banking on the notion that it will be easier to seal the engine at intake and exhaust and pressurize through the cylinder rather than coming up with a lot of different mounts for pressurizing through the intake side. Thanks again to you and Max!

Best,

Matt

[viclioce]

Hey Matt! I need to build a leak down test device and so does Alan. Can you post pics of what you’ve built so we each know what we need to successfully make one? Or if you don’t have pics, can you provide a list of what’s needed? Thanks! Victor

[matt glascock]

I will get some pictures and an equipment list together for you Victor.

[viclioce]

Thanks Matt! I really appreciate it! With 6 horses in the stable now, it’s time I build one! Maybe email me the photos to [email protected]? Victor

[matt glascock]

Hi Victor, Now that we have Covid19 in our community, the hospital is in "all hands" mode. Also, because of my training, I am on rotation with the anesthesia department for critical care duty. Its just been really busy. I will get down to the shed when I can. In the mean time, there is a great description of one in the Hodaka Library on HPI and about a million descriptions for DIY ones on the internet.

[gearyoliver]

Mine

[taber hodaka]

Nice --------------------Clarence