Blow-down test gauge

[David Morris]

Hi All,

I had the good fortune to have a birthday present the other day that others might like to hear about? It was certainly new to me.

It's a cylinder blow-down test gauge. The idea is that you connect a source of high pressure air, from a compressor, to a gauge that is connected to the spark plug hole in the cylinder under test. You set the piston in that cylinder to TDC and send in the pressurised air.

If everything is OK, then you get a reading on the gauge of around 20%, which means there is little leakage from the combustion chamber. Conversely, if you can hear air escaping into the sump and air coming from the oil filler, then you have worn rings or piston bores. Equally, air hissing from the carburettor indicates leaking inlet valves and likewise air from the exhaust shows leaking exhaust valves.

Noting the readings on different cylinders gives you a comparison for now or in the future. All in all, a useful diagnostic tool.

Many thanks for the present!

All the best,

David

[Keith Clements]

https://www.amazon.co.uk/Cylinder-Leaka ... a_1_1_sspa

This one?

[David Morris]

Hi Keith,

No, This one :

WiMas Cylinder leak detector, Leak Down Tester Kit Gasoline Engine Compression Tester Gauge for Car Truck Motorcycle

It is also available from the same well-known store in the sky! But I don't know how to include the link. Just copy and paste the description into their search box.

I think the one you mention measures compression pressure?

One word of caution though. To connect the kit I have to a compressor you need a male to femail snap release adapter, which is not supplied in the kit. It's not compatible with the conventional PCL connectors and my local hydraulic parts store had to order one in specially.

It works well though! I tried it on the Jowett generator and both cylinders came up in the 20% Green zone, which indicates everything in good nick! One slightly better than the other, which confirmed the compression results from a seperate compression tester.

All the best,

David

A

[Keith Clements]

There are many ways to copy a link. All devices and operating systems have a way of selecting text and copying then pasting. So do this on the address shown in the browser address bar which maybe at the top or bottom of the screen, depending on your device and browser.
Many browsers have a share button you can press which shortcuts this to copy to clipboard which you can then paste into JT post.
https://www.amazon.co.uk/Cylinder-Leaka ... a_1_1_sspa
The Wimas looks like it is a branded product that is available with other names and at different prices. Cheapest I found was about £20.

Yes there are at least three types of air fittings requiring adaptors for adaptors.

Whilst the pressure gauge may be useful in comparing cylinders the main diagnostic is listening for where the air is coming out, inlet, exhaust, piston or into water.

[David Morris]

Hi Keith,

Thanks for the sharing info. I will try this next time.

All the best,

David