Question regarding Leak Down Test
Question regarding Leak Down Test
Not to get confuse with compression test, I am about to perform a leak down test.
I got the idea of it, such as get the cylinder at TDC and run compressed air by using some tool.
So, let say I am performing a leak down test on cylinder #1 on a 2JZ, should the spark plug on cylinders 2, 3, 4, 5, 6 remain intact?
Same on cylinder # 2, should spark plug be installed on cylinder 1, 3, 4, 5, 6 ?
First time doing this, and I found so many methods how to put each cylinder at TDC.
I got the idea of it, such as get the cylinder at TDC and run compressed air by using some tool.
So, let say I am performing a leak down test on cylinder #1 on a 2JZ, should the spark plug on cylinders 2, 3, 4, 5, 6 remain intact?
Same on cylinder # 2, should spark plug be installed on cylinder 1, 3, 4, 5, 6 ?
First time doing this, and I found so many methods how to put each cylinder at TDC.
Cylinder 1 - 5 seems have a leak on exhaust, cylinder 6 is mild.
Some air coming out from the twin's downpipe. Intake, crankcase and coolant pipe has no noise at all.
So maybe leaking from the head part of the GTE, could this be valve stems, push rod, etc?
So I guess something about the exhaust valve?
Problems are pinpointed simply by determining where the air is leaking out of the cylinder. Air leaking out of the exhaust system (you can hear it in the exhaust pipe) indicates a problem with the exhaust valve. Air coming out of the carb or throttle body indicates a bad intake valve or seat. Air going into the crankcase is leaking past the rings and does not indicate a problem if the percentage is low enough. A leak where the air is going into an adjacent cylinder or into the coolant indicates a blown head gasket or cracked head.
http://www.gregsengine.com/cylinder-...n-testing.html
Problems are pinpointed simply by determining where the air is leaking out of the cylinder. Air leaking out of the exhaust system (you can hear it in the exhaust pipe) indicates a problem with the exhaust valve. Air coming out of the carb or throttle body indicates a bad intake valve or seat. Air going into the crankcase is leaking past the rings and does not indicate a problem if the percentage is low enough. A leak where the air is going into an adjacent cylinder or into the coolant indicates a blown head gasket or cracked head.
http://www.gregsengine.com/cylinder-...n-testing.html
Im not experienced with leakdown tests but sounds odd that all of them are leaking through the exhaust.
sounds like it would be something in the head but what are the chances of all going bad. are you sure you did it right.
sounds like it would be something in the head but what are the chances of all going bad. are you sure you did it right.
Took off the valve covers and set each cylinder at TDC, lobes facing up. Got different results.
Made a video and posted it at SupraForums, moderator has to approved the post since it is my first one lol.
Will send link here later. Thanks for the input guys!
Made a video and posted it at SupraForums, moderator has to approved the post since it is my first one lol.
Will send link here later. Thanks for the input guys!
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whats the problem? why you doing a leak down test?with cylender on TDC all 4 valves are closed. Valve seals cannot cause anything you can figure out with a leak down test so rule that our right away. Whats sealing the air being forced into the cylender? Piston Rings and Head gasket and Valves those 3 are your only possible causes. Valves are unlikely since Gte is non vvti correct? motor is non interfence no way valve can hit the piston unless you get valve float.
Last edited by MDSC; Mar 20, 2013 at 12:29 PM.
whats the problem? why you doing a leak down test?with cylender on TDC all 4 valves are closed. Valve seals cannot cause anything you can figure out with a leak down test so rule that our right away. Whats sealing the air being forced into the cylender? Piston Rings and Head gasket and Valves those 3 are your only possible causes. Valves are unlikely since Gte is non vvti correct? motor is non interfence no way valve can hit the piston unless you get valve float.
Will do at winter, don't really know the condition of the twins. Might as well take the twins off while the engine out. They said it is a PITA to take them off while on the car.
I see piping from intake manifold going to the twins, what the #$5! should i do with them when I go single. Haven't search yet
SupraForums haven't approved the thread... I guess I have to buy a Supra to be a real member 
Here are the videos, cylinder 2, 3, 4, 5, & 6 has no noise at all. I've checked the exhaust, throttle body, coolant pipe, and crankcase ( oil dipstick ), for air escaping, none at all.
Cylinder #1 is abit different, although the pressure is almost the same as the other cylinders, I hear mild hissing noise at the exhaust pipe.
Also, all pressures are on the "moderate" (yellow) and it should be around 15%( green), is it because the engine is cold? I also did a leak down on my SC300 before I bought the motor, engine is cold and it is on "moderate" as well. My SC300 runs strong at 230K miles. I think I am good on all 5 cylinders, I don't know about the cylinder #1.
#1
#2
#3
#4
#5
#6
Here are the videos, cylinder 2, 3, 4, 5, & 6 has no noise at all. I've checked the exhaust, throttle body, coolant pipe, and crankcase ( oil dipstick ), for air escaping, none at all.
Cylinder #1 is abit different, although the pressure is almost the same as the other cylinders, I hear mild hissing noise at the exhaust pipe.
Also, all pressures are on the "moderate" (yellow) and it should be around 15%( green), is it because the engine is cold? I also did a leak down on my SC300 before I bought the motor, engine is cold and it is on "moderate" as well. My SC300 runs strong at 230K miles. I think I am good on all 5 cylinders, I don't know about the cylinder #1.
#1
#2
#3
#4
#5
#6
i cant view the videos for some reason but 10% difference between the two readings should be pretty normal anything more then 15% is not good. I would do a chemical headgasket test just to make sure you headgasket is ok. If it is then go ahead and boost away.
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