Leak Down Tester

Hi All

I built myself a leak down tester last night. I have attached a few pics. The pic with the 1/8" bung has a 1mm orifice drilled in the centre.

This orifice fits in-between the two gauges (in the Galv socket) to provide a pressure differential so that the amount of leakage can be determined in the cylinder.

COL said:

Hi All

I built myself a leak down tester last night. I have attached a few pics. The pic with the 1/8" bung has a 1mm orifice drilled in the centre.

This orifice fits in-between the two gauges (in the Galv socket) to provide a pressure differential so that the amount of leakage can be determined in the cylinder.

Click to expand...

Ah, interesting.

Two points: (1) Why not a one way valve between the gauges, so one drops and one doesn't?
(2) I'd prefer to be able to connect the gauge assembly to the plug threads after the fitting is screwed in. That weight and length makes it rather easier to mis-thread things. I'd use a short length of tubing (long enough for a 16TS of course) and a plug on air fitting at the top makes more sense to me.

Thanks for the thought too. Good idea...

Cheers

JohnW said:

Ah, interesting.

Two points: (1) Why not a one way valve between the gauges, so one drops and one doesn't?
(2) I'd prefer to be able to connect the gauge assembly to the plug threads after the fitting is screwed in. That weight and length makes it rather easier to mis-thread things. I'd use a short length of tubing (long enough for a 16TS of course) and a plug on air fitting at the top makes more sense to me.

Thanks for the thought too. Good idea...

Cheers

Click to expand...

Hi John

I see your point about cross threading, you could easily put a quick connector in between the long tube and the gauges but this would create a place for a possible leak.

The little orifice that you see in the first pic goes between the gauges to create a pressure drop, the idea is to apply 100 PSI to the leak down tester and if the motor seals properly you should get close to 100 PSI on the lower gauge. Anything reading under 100 PSI will give you a percentage of leak down.

You will need to have the cylinder that you are testing on its TDC with both exhaust and inlet valves closed. Also you need a way to lock the motor to stop it turning over such as having it in gear with the hand brake on (thats if you are testing a motor that is still in the car).

Also the beauty of a leak down tester is that if there is leakage you can quickly find where its coming from by listening at the exhaust, carburetor, crank case, radiator etc.

Hers a link to my other thread on using the leak down tester.

http://www.aussiefrogs.com/forum/technical-performance/103135-using-my-leak-down-tester.html

Thanks - now I understand! The non-return valve isn't so relevant, although it would allow you to compare rates of loss of air pressure from cylinder to cylinder.

My most sophisticated is to bounce the compressions with the crankhandle. If anything is really bad, you can feel and hear it. If bad and audible, dismantle and fix, as more detailed diagnosis isn't going to prevent you having to do the work!

Cheers

John

I like the leak down tester because it enables you to diagnose exactly where the problem is.

There also good for buying second hand unknown motors that you are unable to test drive in a car.