Leak Down Test

[raptor man]

I got my top end off right now and i would like to do a leak down test to make sure the left cylinder isn't sucking in extra air cuz i would always burn up a left pistons befor the right. I thinkthe problem was in my carbs but i just wanna make sure befor i put brand new pistons in it. Could someone please explain how to do a leak down test?
Thanks

[zillaguy89]

first off, put the engine back together...

[bigkahun74]

Originally Posted by zillaguy89

first off, put the engine back together...

thats a good start

[Ed Gein]

Here's a pic of a homemade leak down tester.....

Better than paying $250 for a Motion Pro Kit.....anyways here's what ya wanna do....

1. Take exhaust headers off, plug exhaust ports ( 2 rubber plugs in pic)
2. Take right side carb off, and plug intake boot (hex head plug in pic)
3. Take left side carb off, and insert tester into intake boot (of course tighten up clamps on both sides)
4. The way mine's set up, I squeeze the ball until 6 psi is showing on guage, then close the hand valve
5. Engine should hold the 6 PSI for 6 minutes......If you lose 1 PSI in less than a minute, you probably have a major leak
6. A spray bottle of soapy water will come in handy to make sure your test equipment isn't leaking after you hook it up

Hope this helps you out.......

[dajogejr]

You can spend time hunting down supplies to make this, probably costs about 20 or 30 bucks to make.

R&B racing also sells a kit for very cheap, as well.

http://cgi.ebay.com/ebaymotors/Bansh...spagenameZWD1V

[raptor man]

Thanks guys, that realy helps alot and i hope i dont gota split my case's now if there is a leak!

[dajogejr]

You can check the cylinders, intakes and flywheel side crank seal without the leak down tester, actually. Start the motor up and use a can of carb cleaner to liberally around the base of the cylinder, the intakes and under the flywheel....if it dies down, you've got a leak.
However, the kit is the way to go...period! 6 lbs for 6 minutes is pretty much the standard....but, it can lose 1/2 a pound or so every minute and it's still considered good.
As said, get the soapy water and spray bottle out to make sure the plugs and/or connectors and hoses aren't leaking...

[HardIzzle]

is a leak down test the same thing as a compression test???

[dajogejr]

No....
A compression test will show your cranking compression, (crankcase/cylinder compression) which can be used to tell when the top end is worn, amount of octane needed, among other things.

Leak down tests gaskets and seals throughout the motor, including base gaskets, crank seals, intake seals, etc.

[Ed Gein]

Originally Posted by dajogejr

You can spend time hunting down supplies to make this, probably costs about 20 or 30 bucks to make.

R&B racing also sells a kit for very cheap, as well.

http://cgi.ebay.com/ebaymotors/Bansh...spagenameZWD1V

This kit doesn't look very complete......