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Leakdown Test with Harbor Junk Tool

Wez_

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Ok, well I'm really trying to do this test correctly, but I'm losing faith in this tool. Perhaps it's just my inexperience with both this tool (first time) and the measurement on an engine as opened up as mine.

Basically I can hear the air hissing past the rings into the crankcase whenever I test cylinders 1-4.

This is the most consistent factor.

This has been proven for all cylinders to have an audible hiss of air passing through the cylinder down and out through the crankcase openings. (center engine and side time cover)

The next issue is I'm trying to calculate the % leak down with the piece of Harbor Junk leak down tester.

I had to swap the provided unique Industrial fitting onto my air compressor hose in order to even plug the tool into my compressor...

The supplied fitting to the tool is Industrial fitting which doesn't mate to Mechanical...

Problem solved...but the provided % Gauge gave me INCONSISTANT % every time I disconnected and reconnected to it. I tried everything, but I could not yield consistent measurements with the tool in factory form.

The swapped fitting also leaked at higher supplied PSI. I had to set the tank pressure lower to 75 for the fitting to not leak.

Once all that was solved, I lastly replaced the supplied % gauge with a standard 160 PSI gauge and looked up some videos on how to run the tool.

Downloaded the Summit racing data sheet on their tool and they gave me a formula to use to calculate leakdown % when using different supplied air values other than 100 PSI.

Left Gauge - Right Gauge) / Left Gauge X 100 = Leakdown %

So now, Im at the point where I have a modified Harbor Junk Leakdown Test 2.0.

TDC @ 1.4, connected fitting to cylinder, to the Tool, then connect to 75 PSI air supply with no leaks.

Starting with the valve all the way counter clockwise on the tester, and both gauges at 0, I set the Left Gauge to 60 PSI...

The hissing starts coming out from past the rings and into the crankcase, and the Right Gauge reads 55 PSI...

I calculate the % leakdown and calculate 8.3% leakdown...

Is the hissing past the rings normal for 8% leakdown or does this tester need to be returned asap?

If everything is normal, and there is no need to return the tool, I would love to take the chance to learn something about this tool, this measurement and how to use it and what am I analyzing.

Im sure there are plenty of diagnosis tips and tricks to be learned. I don't want to blame the tool when it could very well be the operator...

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The harbor junk gauge has you connect your supplied air to the tool and open the valve until the right gauge reads 0 - Set, then you connect the tool to the cylinder and read the Right Gauge leakdown %....very inconsistent but yet again, the ordeal with the fittings, then the leak, then having to lower the tank pressure in order for that industrial fitting to not leak makes me feel like I need to return this one and get one ordered from summit racing. what do you guys think?

In all those images of leakdown with the original gauge, you can see that the supplied pressure is considerably low, and this was a major complain online about this tool, not mention the fitting issues......Oh yea....my impact wrench wasn't delivering the same torque from the Industrial fitting. I did a strut swap on my wife's Volvo and sun of a gun, I couldn't get her lugs off. I swapped fittings, and they came off....somethings up here
 
I found a video review of the tool and the old timer broke it down for me. The regulator isn't sensitive enough to set the % gauge properly at such low pressure. He plugged the first hole and ran one gauge. Set it to 100 , then connect it to the cylinder and read the difference. He said the gauge is very inaccurate. Dont t
 
Don't trust the provided harbor junk % gauge. Now Im using the junk 2.0 tool, calculated leakage is 8.3%, 5% so far. The guy who did the review also said the meter was extremely inconsistent and yielded leakage of 30-45% and once he eliminated the factory gauge, he was able to use more pressure, and measured leakage of around 10 % with all the leakage going past the rings he said. Just like me.
 
You simply don't use leakdown testers on normal street engines. You will get read issues doing it. Why?

The testers are worthless past 10-15% true percent as most street engines leak more than that even though they may last for years more. The testers are intended for dragracing only, where you declare a motor as leaking after say 2 runs even though it runs fine and would be good for 5 more years, they measure 5% as a major loss there and that is better than perfect on a street bike. Most new engines off the showroom floor will not hit those numbers, you are requiring perfect honing and rings and valves and seats too.

Another reason why. Is it of even the slightest worth that a cylinder leaks at say 3% when simply staying in one place? Nope, the engine is junk if you cannot use it and why a normal compression test will take you oh so much further to understanding where you are at in the great ballgame. Compression in the real world is accumulative in actual real world use, a leakdown tester requires that you take that logic and throw it out the window. You don't drive any bike with a cylinder at TDC 100% of the time. Watch as you do a normal compression test what the first rotation number is as compared to the final when the pressure quits going up and tell me how one makes any sense. The first number will be nowhere near the final accumulation number and the last is where the bike runs all the time.

I did enough leakdown testing on race engines to establish it pretty much has no worth on street engines, past 500 miles they simply will leak too much to panic everybody for no reason.
 
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School has begun! Thanks amc once again. Is there a way to connect a battery and toggle switch to the engine on my work bench and crank the engine carefully to compression test it?
 
You don't crank an engine over 'carefully' to compression check it, the cam timings and such need to be KNOWN good and the engine gets whirled around until the compression using a proper type test gauge then quits going up. That is like 3-4 solid seconds or so on each cylinder. Using like a 300 psi gauge intended for such and throttle held wide open or carbs removed from engine. ALL spark plugs removed. Battery jumper cables, car battery can be used (jumped off of) but car MUST NOT BE RUNNING!!!
 
OK, I guess Ill drop the idea of hooking up a battery and starter bump switch to the motor on my bench. Ill finish up the top end and carburetor cleaning and install the motor. I'm feeling confident about my work so far many thanks to you guys.

@dan1951, can the solenoid from the wiring harness be installed to the motor/battery externally if I were to create a crankable assembly on my workbench?
 
X2................consider that the engine will try to move around from the torque the starter expends into it.

And NEVER EVER get the idea to crank the starter with the left side cover off, it supports the starter reduction gear axle and it will break the case instantly without that cover in place and tight!! Not the outer mini-cover, the one inboard that holds the ignition pulsers.
 
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