Do you use one? Which one? Do we really even need a gauge to tell us if a cylinder is leaking?

I returned my second Performance Tool tester back to JEG's today. Both acted the same way, at about 80 psi the leakage gauge wouldn't go below 20%. It would do so when dialed back to about 20 psi, but is that even enough pressure to do this test?'

The PT kit I got from JEGs is the same one everyone sells with different labels for around $70 on Amazon and elsewhere. Two gauges, a shitty plastic regulator, and hoses and fittings.

While I am asking, what is the recommended pressure test Big Twin cylinders. Manual only specifies to not feed it more than 100 lbs, which I did not.

 

yes
Tavia
yes
no
100psi is best.

 

A leak down gage set is pretty much for determining whether it's the top or bottom end.

Use a leak down gage set if you detect an issue in the reading from a warm, throttle body wide open, cranking, compression test.

The leak down gage set beats adding oil thru the spark plug hole and seeing if compression rises, to determine what exactly is the issue.

Most AutoZones will loan you one free.

 

a big issue is making sure the engine cannot rotate and most will use the tranny and brakes. all it takes is a tweak of a valve opening to skew your results so use a piston stop on the opposite cylinder.
just remember to remove it and would not hurt to paint it a vivid color.
easy enough to make your own, WAYYYYYY better than stuffing a rope or such down the plug hole!!!

 

How does a leak down test determine, the bottom end is bad?

 

A leak down tester can help you determine whether leakage is going past the valves or the piston rings.

Other than that, they are not a must have instrument (unless you are signing off aircraft inspections).

80 psi is the normal working pressure in the aviation maintenance world, where these things come from.

If the engine is performing well and not consuming oil, there is no need for a compression or leakdown check.

 

Question is directed towards the tool not the test. The test, and the moving TDC piston/valves, I get. Not really asking about that.

You get a tool delivered, you can't get it to zero out before you even attach to a cylinder. Trying a test with it results in bad results. A phone call to customer service results in another new tool delivered. You can't zero that one either. Another call to customer service, but they plainly don't know what to say or do about it. Did you get two bad tools, or are you the problem?

If I am the problem, then I want to know how to correct that. If I got two bad tools, then how can I trust a third one? And if I can't trust a third one, what other tool could I look at sub $100?

 

Didn't read the instructions but with the hose to the cylinder disconnected, the 2 gauges should read the same..


https://www.harborfreight.com/cylind...er-64918.html?

 

The stuff sold for automotive industry is thrown together junk.

To get a good unit, expect to pay over 200 dollars by the time you get the adapters to fit a motorcycle spark plug thread.

You absolutely do not need a leakdown tester, a compression tester is all you really need.

If you get a low compression reading, just use the junk leakdown tester to put 80psi into the cylinder and listen for where the air is escaping.

Forget about the percentage, it is an old archaic way of testing compression in aircraft engines that was never a great method to begin with.

Anyway, here`s a pic of the one I have, from Aircraft Tool Supply:

 

Randallissimo, if your bound and determined to use the leak down method, these two cylinders with huge pistons are a trick to lock up.

Get it to top dead center, lock it in high gear range. (AKA 5th or 6th) and bump it on the garage floor to get drive train play in correct direction and chock the rear tire with two bricks should do it.

Just remember, all that wheel spinning to get that reading really means little.