I did a leakdown test n it loses about 1.5 psi over about 8 min period. I can't find any leaks anywhere. Is it normal to lose that or do u think its inside the case that's leaking?
leakdown test results
- Thread starter Arnold
- Start date
Either your piston rings are worn down, or your crank seals are leaking. Make sure you look over every area on the outside though. You need to be 110% sure that there are no leaks on the outside of the engine.
I have checked a few times. Crank seals aren't leaking n none of the gaskets are leaking. Maybe its time for a top end rebuild. But if I'm going to do that ill probably bore it out. Unless there is somewhere else that it could be leaking from.
rings have nothing to do with a leak test, you can leave the piston/rings on the garage floor and still pass a leakdown test
did you check the tester itself with the soapy water to see if it's leaking ?
how bout your exhaust seal ?
did you check the tester itself with the soapy water to see if it's leaking ?
how bout your exhaust seal ?
A leak down tester treats your engine assembly like a "pressure vessel".
Lets pretend that the engine is a mounted tire. We fill the tire with air to check for leaks.
#1 is it leaking around the bead to rim seal?
#2 is it leaking around the valve stem?
#3 Is the valve core in the valve stem leaking?
#4 Is the rim cracked?
#5 Is there a nail in the tire?
I think you get the point.
It tests all of the barriers between the pressure that you apply and the outside of the "engine".
The "test" applies "air pressure" to the exhaust gasket,reed cage gasket,intake manifold to reed cage seal,cylinder base gasket,head gasket,both of the main seals,and the engine case itself(cracks,and the seal between the case halves.
The test could care less what engine parts are on the inside.
Lets pretend that the engine is a mounted tire. We fill the tire with air to check for leaks.
#1 is it leaking around the bead to rim seal?
#2 is it leaking around the valve stem?
#3 Is the valve core in the valve stem leaking?
#4 Is the rim cracked?
#5 Is there a nail in the tire?
I think you get the point.
It tests all of the barriers between the pressure that you apply and the outside of the "engine".
The "test" applies "air pressure" to the exhaust gasket,reed cage gasket,intake manifold to reed cage seal,cylinder base gasket,head gasket,both of the main seals,and the engine case itself(cracks,and the seal between the case halves.
The test could care less what engine parts are on the inside.
This copy and paiste, Might help understand better.
When the piston in a two-stroke comes down it compresses the air/fuel charge in the crankcase and pushes it, through the ports in the sides of the cylinder, into the combustion chamber. As the piston rises a vacuum is created under the piston. That vacuum sucks the air/fuel mixture through the carburetor and into the crankcase.
When the piston in a two-stroke comes down it compresses the air/fuel charge in the crankcase and pushes it, through the ports in the sides of the cylinder, into the combustion chamber. As the piston rises a vacuum is created under the piston. That vacuum sucks the air/fuel mixture through the carburetor and into the crankcase.
The motor may well be leakproof, but testers have been known to leak.
Spray a little soapy water over all the fittings and the gauge.
The area between the head and cylinder can sometimes be hard to get the spray into, give it a good squirting.
Spray a little soapy water over all the fittings and the gauge.
The area between the head and cylinder can sometimes be hard to get the spray into, give it a good squirting.
I have checked the tester n no leaks. I have soaked every gasket four or five times, I have soaked all seals two or three times n I see no bubbles. The first time I tested it the intake boot was leaking so I fixed that seal but I don't see bubbles anywhere n yet I'm still losing about 1.5 psi in 8 min. I'm still waiting on parts so I can't run it now but I am worried that it will cause problems
Did you spray around the case joint and the motor mountings?
Spray around the face of the gauge, I have known bellows or diaphragms to be leaky.
Pressure has gotta be getting out somewhere, is the Schrader valve on the tester leaky.
Spray around the face of the gauge, I have known bellows or diaphragms to be leaky.
Pressure has gotta be getting out somewhere, is the Schrader valve on the tester leaky.
yeah that leak is gonna be a problem.if you seal and bolt the clutch cover on that will make any inside case leak release pressure through the overflow nipple on the top of the cases. just use your finger and spread some soapy water accross the top of that hole and it will bubble if that is where your leak is at
I haven't actually checked the face of the gauge but I will, n ill try the breather hose tonight. Does anyone know if there is enough clearance for a slightly longer drain plug? I hope I don't have to split the cases again.
how much longer is slightly? you could always add an extra copper washer to it to help shorten it
^^^^^^I thought that I heard something along those lines too, thats why I am asking, I know my piston is getting close to its end but i just want to try to make it last till winter when I am going to do a piston upgrade and a bore, have a local guy that charges 75/hr for stuff like this.
your on to somethin there.... most on here extream the leak test theory..like the guys that say they pumped the motor to 5-6 psi and left it 24 hours and it didnt leak a drop next guy says 48 hours and no diff, its a pissin contest... not gonna get into it cuz youll get tore up but you are somewhat right
