what do u need to do a leak down test? how do u do it? and what do u look for as far as results?

 

What the hell is a leak down test?

 

You'll need a leak down tester, air compressor, and a shop manual (preferably a Honda manual). You screw the tester in spark plug hole #1 and put that piston at TDC. Connect the air and read the leakage. If you suspect a head gasket leak then bypass the gauge and hit the cylinder with the full air pressure -- if the coolant starts bubbling or you see bubbles around the gasket then it's probably trash. Do the same for #2,3 and 4 cylinders. Make sure piston is at TDC for each. Write down the leakage results and compare them to what the manual shows. All 4 cylinders should be close -- if one leaks down significantly faster than the others or all leak down faster than the manual recommends then you'll want to dig deeper.

This test will let you know the health of your valves, rings and cylinder walls, and head gasket. It's more accurate than a compression test because starters turn at different rates and cam settings can also goof up a compression test.

The tool can be had for $60+ but that's a crappy version. Some Autozones will rent you a nice leak down tester and when you return it you get the deposit back. Only thing is if ya break it you're out a couple hundred.

 

gauge

 

Ah, thanks Chain i`ve only ever done compression tests. Learn somethin new every day.

 

No problem. The compression test is a decent tool but like I said, a lot of variables. Basically you can check the compression test results with past results to see if anything has changed.

The best part of the leakdown test is that if your rings are leaking -- you can hear it. If the intake valves are leaking you can hear that also -- same for the exhaust. For the same amount of work taking the bike apart you get more detailed results.

 

here's a link to buy the kit

And here's a write up on how to do it.

A leak down tester uses air from a compressor and measures the rate at which it leaks through the engine. This is done with the engine not running and the beauty of this is that toy can find the source of the leakage by listening for the escaped air. Internal leakge is found by air bubbles in the cooling system. Tools need are a leakdown tester, and an air compressor. Compressor should be at least 2hp and deliver 90psi.

Procedure: Remove spark plugs. Set engine to TDC #1. Calibrate test gauge per the instructions. Lock engine so it can not turn. Conect hose to spark plug hole, Conect pressurized gauge to hose connection. Read leakage. If looking for coolant leaks and nothing obvious shows up, bypass gauge and connect shop air direct to cylinder. Open radiator cap before this. If coolant sprays out, you have a head problem. Do same test on rest of cylinders. Remember to set TDC of each piston for compression stroke. This test is also great for air cooled haed leaks and valve problems. Note that all engines will have some leakge past the rings. I always do full pressure test when I suspect a problem. Make sure engine is secured with full pressure test. it will spin violently. With gauge connected, you can rock crankshaft to see if leakage changes. If so, this is a sign that the ring lands are wearing, new engines will also do this until the rings are seated.

 

hey thanks guys i'll give this a try and let you know what happens.