Using My Leak Down Tester

Hi All

A short while ago I posted a thread about building a leak down tester so thought I would show it in action on a Renault 807-10 motor.

Last November I did a compression test on said motor, these are the results.

Cylinder PSI Dry PSI Wet
1 115 130
2 117 125
3 118 126
4 117 130

I have attached some pics of the leak down tester to compare with the compression test

COL,
Judging by the numbers of replies you've had the readers are either very shy or most knowledgable?
In the past I have used cylinder leak testers, the SnapOn type mainly but I can't see how yours operates.

There's an old maxim out there that says "It's better to ask a question and be thought dumb than say nothing and prove it".:wink2:

Wildebeest, the original thread is only a little way down, started 19 Feb "Leak Down Tester". I see the restrictor is mounted in the adaptor between the two gauges, so the gauge on the left (compressed air input) should remain at near shop air pressure, while the gauge on the right will drop with leakage in the cylinder.

COL, my experience (and maybe Wildebeest can back this up, or not) is that a very good cylinder will have about 5% - 10% leakage, and worn rings, leaky valves, etc, will drop it to 25-30% or more. My tester is an old "Vane" model with a screw adjusted regulator. Your set up is showing very little difference between gauges, but I think the setup should give a good indication, even if the actual percentage leak isn't accurate, it's only a comparison check. I guess it's now a matter of playing with your restrictor, by making it a smaller orifice, you will get a larger differential between gauges which may be a better indicator. Is it mounted to a well-worn engine, or a newish rebuild?

I do like leak down testing to diagnose engine problems, much more informative than compression test, once you actually know there is a problem somewhere.

It's a good tool you've made there.

Cheers.

You guys are probably living in the past. I don't think many people analyse faults anymore. If an engine has a fault, it simply comes out and goes to the tip, or gets a full rebuild if a classic. It's not that people aren't interested, the world just moves differently. Ask Capago if they have one at City Peugeot.

PeterT said:

You guys are probably living in the past. I don't think many people analyse faults anymore. If an engine has a fault, it simply comes out and goes to the tip, or gets a full rebuild if a classic. It's not that people aren't interested, the world just moves differently. Ask Capago if they have one at City Peugeot.

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Or ask any brake shop on the northern beaches if they have a brake fluid pressure gauge (let alone know how to bleed it).

Jo

Wildebeast:
here is the link to my "Leak Down Tester"
http://www.aussiefrogs.com/forum/showthread.php?t=103133

Fordman:
The restrictor (orifice is 1 mm or 40 thou) which I think from the research that I have doen is what most leak down testers use. I'm not sure that I have a drill smaller than that so i will have to run with it for the time.

It only cost me about $60 in parts and an hour or so to put together.

The reason I built it is cause the motor had a lot of oil leaking from it and was getting worse. I did a compression test which showed that there was most likely a ring problem. I had oil in the catch can so obviously the engine was blowing oil out of the rocker cover breather.

The other good thing about the leak down testers is that you can listen to where the leakage is happening (inlet valve; exhaust valve; rings; head gasket).

Also good for when you are buying second hand engines that are out of the car and you cannot test drive.

PeterT:
I do this for a hobbie where my time is free and I'm not paying some mechanic to spend hours analysing problems which cost lots of money now. I like to know what went wrong and why so that hopefully the same mistake will not be made again. I may be old school but there again so are the cars that I enjoy. I think the reason why the modern shops just do rebuilds or engines swaps is pure economics.

My 'old school' motorbike mechanic uses a leak down tester as a matter of course to ensure a proper diagnosis for his clients sake as well as his own.

Living in the past

PeterT said:

You guys are probably living in the past. I don't think many people analyse faults anymore. If an engine has a fault, it simply comes out and goes to the tip, or gets a full rebuild if a classic. It's not that people aren't interested, the world just moves differently. Ask Capago if they have one at City Peugeot.

Click to expand...

Hi
Sure we are living in the past as regards the analysing of faults. Sure the world moves differently. So what :nownow:
Its a free country and if we want to do it properly, as opposed to the sloppy commercial practices current, then more power to us Particularly since it is our own cars and our own money.

I have been appalled at the way my families cars have been f**cked up by the average mechanics who seem incapable of diagnosing anything except by substitution. :crazy: Good profit in the parts though so why not just replace, they never take a part back off and send it back:joker: It makes repairing an older car uneconomic, even if its not French.
jaahn

My mechanic leak down tested my engine a couple of weeks ago after a failed belt tensioner to check the valves before pulling the head off. Came in at 12% across all cylinders which is pretty healthy for the age & k's and there was amazingly no bent valves.

He also timed it up with the old gauge because I supplied an aftermarket crank pulley and he wanted to be 100% sure of the job before turning the key.

He's an Alfa specialist.

PeterT said:

You guys are probably living in the past. I don't think many people analyse faults anymore. If an engine has a fault, it simply comes out and goes to the tip, or gets a full rebuild if a classic. It's not that people aren't interested, the world just moves differently. Ask Capago if they have one at City Peugeot.

Click to expand...

We do!