Can I do this myself?

[krue]

What do I need to build a cylinder leak down tester? I have a compression tester (borrowed) and some regulators laying around. Can I build my own, and if so how do I use it?

Thansk, krue

[beaterC10]

It should be fairly simple, the aviation community uses these on recip engines. Alll you are doing is comparing the air pressure loss in a cylinder against a known air pressure. You would need two pressure gauges and regulators. I remember using these in A&P school about 12 years ago, haven't used one since though.

If I can remember some of the aviation tool suppliers I will post them. Seems like Jegs and Summit sell them also.

Dave

[walker]

All I did was knock the ceramic out of a spark plug and welded an air chuck fitting to it. You don't really need a guage, just hook your air compressor to it at full blast. Then listen at the carb, muffler, or coolant fill neck. Your leakage will be apparant. Just be sure to bring the cylinder to TDC and wedge a breaker bar, on the crank nut, against the frame , or it will move the piston down, Rapidly! Don't ask me how I know that last part.

[jimfulco]

http://www.xs11.com/tips/misc/misc3.shtml

If you already have a compression tester, you could cut the hose & use the engine end instead of beating up an old spark plug, and use quick-disconnects so you could use it on both compression tester & leakdown testers.

I built one a while back using a gauge on both sides of the regulator, but I didn't use a "damper valve". Maybe that's why my 70,000+ mile 305 showed only 2% leakdown.

Let us know how it works.

[Jeepster376]

I built my own by hollowing out a spark plug and brazing a compressor male quick release fitting to it, then I made a 3 foot peice of hose with a paint spray gun regulator (valve) with a guage on one end and a female quick release on the other. I set the big regulator on the compressor to 100 PSI, then set the little hose regulator so that the guage reads 0 psi while free flowing with the spark plug adapter attached. Pop out the adapter to stop the flow and the pressure should read 100 psi. Now screw the adapter in to a spark plug hole, and plug on the gizmo, and the guage will give you a relative reading somewhere between 0 and 100 psi. The actual PSI reading is not as important as consistency.

And Ya don't forget the breaker bar on the crank. 100 psi on your piston can develop a few hundred foot pounds of torque on the crank if the piston isn't at TDC.

[krue]

Thanks, guys.

[Jeepster376]

Originally Posted by jimfulco

http://www.xs11.com/tips/misc/misc3.shtml

If you already have a compression tester, you could cut the hose & use the engine end instead of beating up an old spark plug, and use quick-disconnects so you could use it on both compression tester & leakdown testers.

I just read your link, that looks just like how I made mine. And here I thought I had a unique tester.

Most compession guage hoses have a check valve built in to the spark plug adapter, so it will not work for leak testing.

As for hollowing out a spark plug, rather than busting it with a hammer sending shards of porcelan everywhere, just grind the rolled edge above the hex part. Once you grind away that part the whole porcelan peice will pull right out in one peice. I've made several adapters this way.

[krue]

btw that link is just what I needed.