Excellent video. One suggestion, just to be safe you should remove your ratchet or break over bar from the crank after you find TDC, and before you pressurize the cylinder. There is always a chance that the piston could be forced down by the pressure and rotate the crank.
Perfect video. You didn't leave room for any guess work. That's a nice trick to know in determining how to find TDC. No one else on RU-vid mentioned that but you. Now I feel confident in doing this for my 2014 F150 What should you do before removing the hose from the engine?
This is one of the very few videos on RU-vid that shows the correct way to do a cylinder leak down test. It’s nice to see a video by someone that knows what they’re doing. So many videos shows ridiculous ways to find TDC when the leak down tester is the best and fastest way to do this. As shown in this video. The only advice I would give is to take the break over handle and socket off the crankshaft bolt. If the engine comes off of TDC it will spin and rotate that break over bar fast and hard.
Very informative test when examining a used engine, or just want to find out where you are losing compression on a cylinder. I recommend removing the wrench from the crank bolt before applying pressure to the cylinder, just in case you miss exact top dead center and the piston cycles from the pressure (rotating the crank and the wrench - and possibly striking your hands - ouch - I've seen it). And some leakage past the rings is normal (but you can hear the difference if a piston is blown). Any air leaking from the intake or exhaust areas is not good and mean the heads need rework.
I was going to say the same thing! Great video, but I would make sure to tell people to remove the socket and ratchet from the crankshaft bolt (edit it into your video, for safety reasons) If you are not exactly at top dead center, the piston will push back down when enough pressure is built up in the cylinder and the socket and ratchet will fling around and could possibly injure yourself or someone else.
And you’re right, thanks for sharing, only leakage that’s normal for good engine is past the rings. Should be zero past any valve!!! Why didn’t I mention that in the video... oh well, try to get it next time. Good add buddy - thanks!
Love the content and teaching us the Subaru way 😂😂 . Would you make a video of what tools you use for engine tear down and tools you keep in your shop !!
Hello! How would you determine a leaking head gasket or blown head gasket or do you have to use the Radiator tester for gases that turns the blue fluid green or yellow? Thanks for sharing and teachings. Cheers from Motown
I was going to buy that leaked down tester, but it’s so cheaply made and too expensive you can buy a $50 one that’s way higher quality and the $50 one even comes with the long tube that reaches down into the spark plug hole so you can actually get a proper seal and not worry about ripping your hose down in there
other way to find TDC is to insert a screw driver into spark plug hole and turn the motor until the screw driver raises to top position at TDC stays there for a little while
I prefer a chopstick. Less chance of scratching something or damaging spark plug threads. Once I find TDC on one cylinder, I mark the chopstick and this makes finding the other cylinders quick and efficient. And this is MUCH more accurate than trying to use the gauges as a surrogate. No real mechanic would do that as it simply isn’t accurate or consistent enough.
Hello i just got my otc tester from ebay. Its my first time ever doing a leak down but the guage doesnt reach 100. I turn the knob alll the way and it gets to about 80 at most. Ever had this problem? I hope you stay active on your youtube. Thanks
Thanks for the video, Luke. Newbie question: Just curious, would it be normal to find a higher leak percentage on an engine that is newly built and never run/broken in? I’m wondering if freshly honed cylinder walls and new piston rings could affect the readings if I the piston has never reciprocated or been through any heat cycles... or would that even make any noticeable difference on the gauge?
That’s a great question. Tbh, I haven’t done a leakdown on a fresh ringed engine, it’s always been after break in, if it all. (Which was a mistake, I should’ve leak tested my engines over the years much more than I did, I know better now). To give my best guess, I would say yes it probably would make the leakdown more pronounced and potentially look worse than it will be once the rings have fully seated.
This guy failed to tell you to listen for air escaping threw the cooling system meaning threw the radiator or along intake manifold to head mating surfaces this would tell you you have a leak do to a blown head gasket between cylinder and cooling ports in the combustion chamber or possibly a cracked head or engine block
I use both, but really the leakdown test is the end all be all, that tells the whole story. If you run a compression test, you still could be fucked, run and leakdown and you know you’re good to go!!!
Luke, I know this is a leak down test, but is it possible to also do a compression test with the bare long block as you hace it here? Or does the motor has to have the intake manifold, turbo, and rest of the parts, attached to the long block before proceeding with the compression test?
Nice video. I liked the way you used the OTC tester to find TDC. Do you think I can use it the same way to check for TDC on a small engine? Example: a snowblower engine. Thanks.
I wonder if the air has to be turned on when finding TDC; I see that the airline is connected but I don't know if the gauge valve is turned on. I never used the leakdown gauge before, but I ordered an OTC just like that one, just have to learn how to use it.
@@SubaruONLY thanks for the response but you answered only one of my questions; maybe it is obvious but I don't take anything as obvious when it comes to these technical things the part about the air being on or not can you find TDC with out turning on the air to the tester or does it have to be on , I like to be sure before I start rather than guess. Thank you
I don’t normally have the air ON when finding TDC, just watch the small spike in pressure created by the cylinder moving up or down in the cylinder bore 👍
At 70 to 80 PSI, the air in the cylinder starts to leak past the o-ring on the hose threaded into the spark plug hole. Any thoughts on how to get a better seal at that point?
Several poor techniques here. First, you should set TDC mechanically, not using pressure rise as a surrogate. Not hard to be several degrees off that way. Consistency matters in tests like this. Second, NEVER use a tool at the extremes of its range. You should not be using 100 psi for testing. Aviation uses 80 psi for good reason. It is assured to be well below the pressure provided by most compressors and it is well below the maximum rated pressure of the gauge and more likely to be in the linear and more accurate range of the gage. This video should be retitled to say “How NOT to perform a cylinder leak down test.”
Hi, Total newbie and Novice, I want to learn the correct technique, I have a BMW e46 330, Is there a mechanical way to get TDC without removing my rocker cover, lot of work and costly replacing gaskets if not?
@@danielocallaghan8517 Some engines have a mark on the harmonic balancer or front pulley that indicate TDC. If that isn’t available, a chopstick in the spark plug hole will get you pretty close. The easiest way, but less accurate, is to just turn the engine until the chopstick is extended and not moving up or down. A more accurate way is to get the chopstick where you think TDC is and then turn the engine until the stick drops about 1/2” and mark the stick against a reference point on the head or valve cover. And mark something on the crank (pulley, balancer, etc.) against a reference on the engine. Now turn the engine past TDC until the mark on the chopstick comes back to the reference point on the other side of TDC. Now mark the crank again. Now locate the midpoint between the two marks on the crank pulley or balance and turn the engine to this midpoint and you will be very close to TDC.
