I worked in a part 145 engine overhaul shop, ran the test cell on overhauled engines. The biggest indicator of a vacuum (induction) leak is a rough idle. A&P/IA
Great video. Simply explained so it makes sense even to pilots. I am so trying to not be the pilot that’ says there is something wrong with my plane, fix it. Now I can say, there was a bigger than normal drop on the mag test. Check for an induction leak. Plus all the others reasons. I didn’t know an induction leak would do that.
Yeah, I work in maintenance and some mechanics might not like it if you tell them what test to perform.. just saying. Tell them what you've experienced and maybe you can add something like "I don't know if you need to do a leak test or something cause I'm suspecting a leak.." something like that would be better :)
Any intake leak will cause an lean condition on one or more cylinder . Aircraft or not . It is not good at all . Repair the leak and test again . Do another wet compression test to see any improvements . If none then take down that cylinder and start a cylinder and head crack test . If passes then put it back together . I done this on my BMW boxer engine after an lean burn . A&P think they are so special and the work they do but to me it used to be an everyday event Aircraft engines are easy to work on and do a rebuild . But everything in that engine can fail if not checked or tested . Being safe is just one thing .
Don't start with 80 psi. Find TDC at the cylinder you are working on, reduce pressure to 0 at the pressure regulator knob, open the shutoff valve and slowly increase pressure up to 80 psi. Much easier on the arms.
with 80 psi, you can hold the prop and prevent any random movement of the prop. Don't walk/idle in the arc of rotation without being prepared to stop it. Tip: Creep the air to the proper p.s.i. Always refer to the proper manual before performing any task. Adhere to all cautions/warnings and read all notes within the manual.
I think you skipped an important part of this test. Don't you need to seal the intake source in order to pressurize the system? Taping off the intake on the carb box?
I was thinking the same thing myself. However would the fact that the throttle is closed, cause enough restriction to allow the air coming out if that cylinder to pressurize the manifold, although for a brief time?
While I respect the opinion of any licensed A&P posting negative comments here, the test they performed clearly revealed leaks in the induction system. What am I missing here?
These guys should not be allowed to get anywhere near a engine. Lets see if I got this right Plug in is in #3 cyl not #1 Up at tdc, open the intake valve ? then the intake is some how pressurized ? Top that off air travels to #1 intake, through the cylinder. How can this happen ? The explanation about the mag drop is crazy mindless dribble, or am I wrong ?
Many thanks. I thought it might be me. Insane if true. I am a little older than you. 40 years A&P and pilot Alphin Aircraft Hagerstown Md. I have never seen anything this stupid. I should just click off. Loads of garbage on the net. Again thanks for your support !1
@@pauleyplay It's an intake manifold, so it doesn't matter from where you supply the air, the entire manifold will pressurize. If there is air compressed in the #3 cylinder and the prop is turned to open that intake valve, that will send the compressed air into the entire intake manifold. It doesn't go through the cylinder, it goes through the manifold.
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I worked in a part 145 engine overhaul shop, ran the test cell on overhauled engines.
The biggest indicator of a vacuum (induction) leak is a rough idle.
A&P/IA
Good presentation, thanks!
great job
Great video. Simply explained so it makes sense even to pilots. I am so trying to not be the pilot that’ says there is something wrong with my plane, fix it. Now I can say, there was a bigger than normal drop on the mag test. Check for an induction leak. Plus all the others reasons. I didn’t know an induction leak would do that.
You are right it does not.Unless the intake tube is sealed they checked nothing
Take a video of you telling the mechanic what to check I wanna laugh
Yeah, I work in maintenance and some mechanics might not like it if you tell them what test to perform.. just saying. Tell them what you've experienced and maybe you can add something like "I don't know if you need to do a leak test or something cause I'm suspecting a leak.." something like that would be better :)
Good work my friend
tenk yu. very gud
Gentlemen well explain
Any intake leak will cause an lean condition on one or more cylinder . Aircraft or not . It is not good at all . Repair the leak and test again . Do another wet compression test to see any improvements . If none then take down that cylinder and start a cylinder and head crack test . If passes then put it back together . I done this on my BMW boxer engine after an lean burn . A&P think they are so special and the work they do but to me it used to be an everyday event Aircraft engines are easy to work on and do a rebuild . But everything in that engine can fail if not checked or tested . Being safe is just one thing .
Don't start with 80 psi. Find TDC at the cylinder you are working on, reduce pressure to 0 at the pressure regulator knob, open the shutoff valve and slowly increase pressure up to 80 psi. Much easier on the arms.
To do this you have to put yourself in the prop arc so the warning doesn't make sense
with 80 psi, you can hold the prop and prevent any random movement of the prop. Don't walk/idle in the arc of rotation without being prepared to stop it. Tip: Creep the air to the proper p.s.i. Always refer to the proper manual before performing any task. Adhere to all cautions/warnings and read all notes within the manual.
I think you skipped an important part of this test. Don't you need to seal the intake source in order to pressurize the system? Taping off the intake on the carb box?
at the very least ! Pressure check nothing
I was thinking the same thing myself.
However would the fact that the throttle is closed, cause enough restriction to allow the air coming out if that cylinder to pressurize the manifold, although for a brief time?
Could you use a smoke machine?
@@tpcoachfix yes
While I respect the opinion of any licensed A&P posting negative comments here, the test they performed clearly revealed leaks in the induction system. What am I missing here?
May I know what is mag?
It’s short for “magneto” which is the part in a piston aircraft engine that essentially generates power for the spark plugs.
Ahh thank youuu
Thats #3 cylinder not #1
These guys should not be allowed to get anywhere near a engine. Lets see if I got this right Plug in is in #3 cyl not #1 Up at tdc, open the intake valve ? then the intake is some how pressurized ? Top that off air travels to #1 intake, through the cylinder. How can this happen ? The explanation about the mag drop is crazy mindless dribble, or am I wrong ?
This must be a spoof! Ive been an A&P / IA for 30 years. This is total bullshit
Many thanks. I thought it might be me. Insane if true. I am a little older than you. 40 years A&P and pilot Alphin Aircraft Hagerstown Md. I have never seen anything this stupid. I should just click off. Loads of garbage on the net. Again thanks for your support !1
@@pauleyplay It's an intake manifold, so it doesn't matter from where you supply the air, the entire manifold will pressurize. If there is air compressed in the #3 cylinder and the prop is turned to open that intake valve, that will send the compressed air into the entire intake manifold. It doesn't go through the cylinder, it goes through the manifold.
@@c5mmechanic I was thinking the same. The entire intake should be pressurized by the opening of one intake valve on any cylinder.
WTF?!? are tweedle dee and tweedle dumb mechanics ? Never seen anything this strange in my years working on a/c engines.
May I ask what's wrong?