Leak down test

[jerkputter123]

I have done leak down tests in the past on trucks but it was easy . Small engines with one cylinder I have a problem doing this test. How do others check one of these small engines like a generator and keep the piston from moving ? Engine has only 48 pounds of compression and I wanted to see if air was leaking by the valves. Lawn mowers I can put something around the crankshaft but this Briggs . I got the flywheel cover off it but I just can't find a way to clamp it down.

[KE4AVB]

Well this is one that you need to use a strap wrench to hold the flywheel or the a special designed holder. I even old connecting rods made into crankshaft holders that uses the keyway to prevent the crankshaft from rotating.

But I don't have this problem as I use a low pressure leak down tester from HFT that I got that only uses 10-15 psi instead of 100 psi for testing. With it I am able to hold and rotate the flywheel by hand. This allows me to remove the push rods on OHV engine and test the entire piston stroke. In what I called a modified leak down test as I can test for tapered and ovaled cylinders. I had one engine several years ago that would pass the standard leak down test with flying colors but failed when I tested the lower part of the stroke.

[lefty]

Can you post a link to that tester? I'd be interested. My current method is to put a breaker bar and socket on the flywheel nut. But that requires additional disassembly and ties up one of my hands. And I'm not a fan of putting loosening pressure on the flywheel nut/bolt.

[jerkputter123]

Can you post a link to that tester? I'd be interested. My current method is to put a breaker bar and socket on the flywheel nut. But that requires additional disassembly and ties up one of my hands. And I'm not a fan of putting loosening pressure on the flywheel nut/bolt.

I used a short 1/2 drive extension and 22 mm socket with my large 1/2 drive pull bar and did what you said you don't like to do today. I eased the air pressure up with regulator to 50 psi. That will be enough to make sure the valves are not leaking and they are good.
I have the gas tank off this generator and I used the frame to support my pull bar . I never took my hand off it because I know it had some pressure on it and I wasn't standing in the way in case something happened.
lefty, I made my leak down tester from instructions I found online. Already had most of what I needed so I have very little in it. It works as good as a store bought one.
I set the valves on this engine to what the manual said but on the high end - .004 on both. I was thinking the exhaust would be more than intake but not according to the manual I downloaded here on the 185400 series. They say .002-.004 on both intake and exhaust.

[KE4AVB]

Lefty, Just went to Harbor Fright site and they no longer carrying the one I got from them.

But I have found a similar one on Amazon.

Leak Down Tester on Amazon

[38racing]

Lefty, Just went to Harbor Fright site and they no longer carrying the one I got from them.

But I have found a similar one on Amazon.

Leak Down Tester on Amazon

I didn't like the one that shows leak down on 2nd gauge. I replaced it with a gauge matching the first one and then calculate the leakdown. I also eliminated the quick connect as mine was actually a source of leak.

[KE4AVB]

Everybody got their preferences...and problems. Personally it is better than the homemade I used for years. I have had any problems with the quick connect on mine. I did destroy the percentage gauge on my first one as you got reduce the regulator back to Zero before initial use everytime as when first connect the air hose full pressure is seen on the output hose.

Here I use V style couplers and plugs. They will accept M style plugs but will leak over time and the O-rings have to replaced every so often. Currently my problem is something happen to the compressor Friday. There was a strange pop while it was running. It will tale time to dig it out of it storage space. lots of stuff in front of it. I think I think might have lost the compressor itself. But considering it nearly 40 yrs old it had a good life, just don't need it failing right now as a lot things failed here this year already. Going to put me in the hole for the year. First lost in business profits in 14 yrs.

[jerkputter123]

Can you post a link to that tester? I'd be interested. My current method is to put a breaker bar and socket on the flywheel nut. But that requires additional disassembly and ties up one of my hands. And I'm not a fan of putting loosening pressure on the flywheel nut/bolt.

lefty loosey”“righty tighty, lefty is correct . I turned the pressure today up to 70 psi on my tester . It loosened the flywheel nut just like lefty said it would. Not sure my homemade tester will work or not and to be honest its a pain to hold one of these engines.
I have less than $15 in the tester and may just end this project.

[38racing]

if my pto shaft is exposed I have put a wide weld pulley hub on it with key in. Then I put 2 pair of vise grips at about 180 apart or whatever angle works so a pipe on each pair extends to the bench or something solid. Set so one pair stops 1 direction and other pair stops other direction.

[Arkie]

Also be aware that a upper cylinder leak down will sometimes show ok.

As KE4AVB pointed out.

I had a Briggs twin Intek that was a smoker, oil burner and the spark plug on one cylinder showed such also but it would pass the leak down test both hot and cold.

I did a lower cylinder test and got the bad readings.

Also I found that most generally no need in a really high pressure to get a percentage leak down result.

My leakdown tester saves me lots of time on a new to me engine that is not running. I do the leak down before even going any further with trying to get the engine running. I bought a OTC back when they were priced within reason and it's served me well.