Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

   I picked up a leak-down tester and have a question about the input pressure side.

   It's a standard tester.  There's an airline in to a first pressure gauge which reads 1 to 100psi.  This gauge has a regulator.  Then their a restriction after which there's a second gauge.  The second gauge read in percentage 100 to 0 %.

   The opereration is to input pressure and zero the second gauge to zero percent leakage.  The gauge set is then connected to the sparkplug hole.  There's some expected leak which is read out on the second percentage gauge.  It's a percentage of the pressure from the regulated first gauge.

   I tested four engines and the leakage readings were what was expected for those engines so the gauge seems to be working fine.

   The issue is how to change the pressure in.  No matter what pressure I put in from the air compressor the the reading is always the same about 15psi when I zero the percentage gauge.  If I set the regulator on my compressor to 20psi then zero the tester the reading on the first gauge is 15psi.  If I set the regulator on the air compressor to 60psi and zero the tester it still zero's with a pressure of 15psi. 

     I would think that if I put in different pressures then the zero should happen at a different pressure on the tester first pressure gauge.  It always zero's at 15psi no matter what pressure is applied from the source.  Does that sound right?  That for different imput pressures the gauge should zero at different pressures?

trouts1

trouts, you may not have sufficient line pressure to make the tool work properly . i've never used one on a small motor but testing car engines you set the pressure to 90psi, spin the engine to close the valves sand hope to see a drop of 10% or less.

CMS5310,

    It could be pressure in.  Since there is no adjustment on the tester and a dial that can go from 0 to 100psi I would think there should be some way to get the think to different settings.

    My source is a Craftsman that has two gauges one reads 0-200psi tank pressure and the other 0-200 regulated out.  If my source is only putting out 15 then that could be the problem.  The tank gauge goes up while it runs so seems to be filling the tank.   The regulator knob at least makes the dial arm move around to various settings but it might be only 15psi and the problem.  ?? 

   I'll have to figure out some way to test it's output.   I've got a compression gauge.  Maybe I can connect that and adjust the regulator and see what happens.

JUST WENT OUTSIDE AND TRIED IT:

    Attached the compression gauge to the output line from the source.  When I vary the source the compression gauge tracks with the source up to 80psi and down again.  I again tried putting various source pressures into the leak-down tester but no matter what pressure is in the line when I turn the LD tester regulator it zero's the precentage meter and the the pressure is 15psi on the regulator gauge. 

   The tester is not working properly.  Either the regulator always regulates at 15 no mater the input amount or if it is regulating a higher pressure only reads 15 so either way not behaving properly.    I just picked it up from Harbor Freight so will return it tomorrow.  It was 30 bucks so a low ender but should work.

LATER STILL:

    Returned the tester and got another.  It does the same thing so I guess this model gauge does leakdown tests at 15psi and that's it.   There is turnable nut on the regulator so maybe that can be worked to get a higher psi base.  They must have set these at the factory to be 15psi so may be there's some internal adjustment to get it higher.  At 15psi it's seems to be ok for small engines on snowblowers but probably is not enough pressure for a car.  For reference it a US General 94190 and sells at Harbor Freight but some places on the net sell these for 90 which is a rip. 

LATER AGAIN:
  

    UTube has a video with this gauge and the source was a compressor like mine.  The source was setup to 100psi then they set the tester up and zero'ed it which came out to 15psi like mine.  

Later Later:

   Talked with Harbor Freight tech support and the gauge is calibrated at the factory to 15psi.   The gauge has one pressusre setting where the gauge will zero and that is set to 15psi.  It determined by the opening between the two gauges and the regulator calibrated with that opening so the zero happens at 15psi.

Hey Touts,

The leak down testers I use are factory set to a psi AND have a calibrated orifice in them to only allow a flow rate of a factory preset cubic feet per minute. 

This is to set a Standard in troubleshooting...   You could always overcome a leaky engine by adding more cubic feet of air per minute,  which would make the trouble shooting worthless..

Good Luck,

Friiy