I build a leak down tester.
FIRST I HAVE ALWAYS HAD ONE, LOADED IT OUT. IT HAS YET TO RETURN!
ALSO I AM SURE THERE IS A LOT OF INFO AND RESOURCES FOR THIS.
I am just bragging about my over kill!
Let me start with, if you don't have the tools and some parts, building your own is not economical. You can purchase one on the E-bay for around 50.00 quality? I don't know.
Things you will need.
1/8 NPT pipe tap
#60 drill bit .040
Brass or steel fittings.
And old compression gauge (or a new one)
a "M' style female coupler
"M" style male nipple
Things I have, so i just put them to use!
I have a old compression gauge, (I got me a new digital one)
This saves some major work. Most have a "M" style air compressor fitting. The parts from compression tester, hose & adapters for connecting to engine will be used.
I have some big gauges that I purchased during the winter on a e-BAY deal! (major reason for building my own)
these are some very accurate Trerlce quality gauges.
AND THEY ARE BIG!!!!! 4.5 inch dia.
NOTE: I have a cheep air regulator, I will update in the next day or so.
Most important part in building this tester is what is called a damper valve. This is a small orfis between the regulator & hose used to connect to the engine. This is also were the measurement gauge is located.
NOTE: lot of instructions of home made units on the net do not show a damper valve needed. YES IT IS NEEDED!
The industry standard is a .040 hole, or #60 Drill bit.
Now as I am sure you have already checked out the pic's I have used 1/4 pipe nipples on both sides of the regulator. The damper valve will be installed on the down leg of the regulator.
Building the damper valve:
If you use a 1/4 like I did, you can tap the inside of the nipple with a 1/8 pipe tap (the id is perfect 5/16)
So you can screw a pipe plug into it. That I drilled the .040 hole into.
Also, I feel a gauge on the air supply is very important to know. I like to feed it with 125psi plus.
And regulate to 100psi.
If you use 100psi pressure the math is easy to figure, you feed in 100psi, if the gauge reads 90psi, you have 10% leakage. Or your cylinder is 90% sealed.
i love it. I got one of them POS eBay deals and it wasn't worth the money for shipping. Where did you get the pressure gauges from?? are they old or new?
It looks like a nice, easy to read tool, but how do you calculate that 90/160 = 10% leakdown?
from old mag article
here is the procedure I hav 2 articles complete from the 70's I can post if wanted.
Connect the tester's regulator input to a compressed air source having at least 100 psi pressure. Slowly turn the regulator control clockwise until the tester's gauge registers 100 psi. Now connect the tester's female disconnect to the hose attached to the engine. The gauge reading will drop suddenly, then rise as the compressed air fills the cylinder. It will not, however return to 100 psi. Subtracting the gauge reading from 100 indicates the "percentage of leakage." (For example, a reading of 96 equates to a 4 per cent leakage; 100-96=4.) Disconnecting the hose from the tester's female fitting will release a jet of air from the hose and restore the gauge to its 100 psi setting. Test each successive cylinder by removing its spark plug and bringing the piston to TDC.
Perhaps your design is different, but the leakdown tester I have, and others I have seen used, work on the percentage difference between the guages.
If the one guage reads 100 PSI and the other 90 PSI, that is 10% leakdown.
If the one guage reads 120 PSI and the other 90 PSI, that is 25% leakdown.
The instructions with my leakdown tester recommend setting the one guage at 100 PSI to keep the math simple.
Use whatever air pressure YOUR system can maintain.
Ok, the 2 gauges,
The right gauge is air supply, It there more for reference to make sure you have over 100psi plus psi to gauge. The right gauge is not needed.
The left gauge is zeroed (using the pressure valve) to 100psi before you hook up to cylinder using the quick disconnect.
The right gauge could be mounted between the regulator valve and the damper valve like some gauges are made. And adjust both gauges to 100psi.
the right gauge is not a factor, only verification of air supply.
leak down tester
Er.. I realy feel silly about asking this but what is it used for?
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