Thread: Leak down test - I got a leak!
05-28-2012, 09:49 PM #1
Leak down test - I got a leak!
Performed a leak down test with a set of racket balls and the $25 harbor freight hand vacuum pump. To my disappointment I could literally patch the vacuum on the gauge dissipate. The good news is that I could hear it coming from the front of the engine. The racket balls seem like a good method, but any chance air could be slipping past them? I used tons of grease to get a good seal.
FYI on 2 of the 3 air intake ports i just sat the greasy racketball on top as I could not get them to stay in the ports. Trying to get them to stay in the ports is a major PITA especially with grease all over them.
Now finding the leak------
I don't think i can use the balls as they'll probably get ejected. There will most definitely be a leak at where the balls are just sitting on the ports. What can i use to block them off?
Any ideas on a cheap local air pump with a gauge on it that I can use for this? I was thinking a handheld bike pump, but i would need to somehow adapt a schrader valve to 1/4".
05-29-2012, 12:49 AM #2
Use soapy water, spray it around areas you suspect if there is a leak it will bubble up you can eliminate them one at a time till it holds pressure.
05-29-2012, 08:17 AM #3
I saw someone using rubber stoppers for the intake mani. You can get them at a sears hardware store or similar for a couple bucks each....
05-29-2012, 08:44 AM #4
- Join Date
- Jun 2010
- Milwaukee WI
I made plates by tracing a gasket. I used 3/8 clear acrylic, you could also use aluminum. Bolt them on with gaskets, or I use a little RTV. Works perfect.
05-29-2012, 10:41 AM #5
great ideas guys. The block off plates sound excellent, but I think i'm just going to pick up some rubber stoppers like bluefish recommends. Less time consuming is ideal right now.
Any ideas on a pump cheap local pump solution I can pick up? What do you use bluefish? I'd like to get out on the water asap
05-29-2012, 10:50 AM #6
I'm just praying there's no leaks at the crank seals on either of my machines........
05-29-2012, 11:20 AM #7
Yeah... putting the engine under vacuum works to find leaks... but you gotta listen for them. If you want to try soap bubbles... you need to put the engine under pressure so the air leaking out makes the bubbles.
I too use raquetballs. I put one each in the exhaust ports on each cylinder... then put one each in the intake opening below where the carb sits. Now to get them to stay when I pump pressure in (using a hand tire pump on the fuel pulse port) I put a small piece of wood across the 3 exhaust balls and ratchet strap that board around the cylinders... then stuff a wadded paper towel under each carb throttle plate and sit the carbs (all racked together) on top of the intake balls and use the carb bolts to hold those balls down. Sounds funny and looks funny... but with a little play... it does work. Then I pump the engine and listen for hisses and spray some soapy water on suspect areas like around the crank seals.
05-29-2012, 11:54 AM #8
05-29-2012, 09:36 PM #9
- Join Date
- Oct 2006
- Cleveland OH
05-30-2012, 06:28 AM #10
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