Cylinder Leak Down

How to perform a cylinder leak down test and interpreting results.
Funded wholly through the VCCS Office of Professional Development.

[@lizardking8388]

Here's how I find top dead center when doing a leak down test: 1) Connect tester to the cylinder you want to test. 2) Hook up compressor with low (~10 psi) pressure. 3) Turn the engine by hand while looking at the needle on the leak down tester. 4) Watch for the needle to rise (indicating compression). A falling needle indicates an open valve. 5) Keep turning until the needle stops rising (just starts to fall); you may have to back off a tiny bit. You are now at TDC and you can use full pressure to do your test.

[@roccomiers477]

Great job! One suggestion - if you turn the air pressure up on the tester gradually instead of plugging it in at 100 psi, it will be less likely to push the piston down to BDC.

[@dah8rsluvme]

Very well explained and informative. Unlike other KZbinr spending over 20 mins on poor explanation

[@train4905]

I would like to say ,young lady.that was an absolutely butiful video.very clear concise, Well done keep up the superb videos,av just subbed,ste from the uk

[@daryllect6659]

Using the dipstick is such a cool idea!

[@Iwhishihadyoutube]

I normally don't comment in videos and I've never subscribed to anyone before but I did to this. I think your video is great you spoke clear, explained each step clearly and why you were doing it. I do agree with the comments on starting at 0psi and moving up to 100, that is how I do mine. That being said using your method works and has obviously worked for you. Thank you for this video and keep up the great work!!

[@joewalton8812]

Phenomenal video, probably the best auto tutorial video I've seen on KZbin.

[@brettb.7425]

You do a great job with your video. I haven’t used a tester like this in years and needed to know the settings again. Now I remember because of you. Thank you very much!!! 👍🏻👍🏻👍🏻

[@jorgedeleon2315]

Great video! I love the oil dip stick trick, I've never heard or seen that done before. Definitely made performing this test easier to do and understand.

[@princeclive1913]

You can use a small balloon on the hose to determine the rising of the compression stroke when the balloon starts to get bigger..

[@robertrumfelt7843]

Well done, Laura. You are a good teacher.

[@turbodave231]

I like your video. I've watched plenty of other techs using leakdown testers. You do a great job and you are using the snap-on tester (which is what I use when teaching engine diagnosis). It would be good to mention that the leakdown adapter hose does not have a schrader valve. If you also have a snap-on compression tester, it is easy to get the adapter hoses mixed up. That always causes confusion with students.

[@DYImechanicTuro]

Perfect description. A lot of dudes posting videos can come here and get educated.

[@dragonmybehind]

I could not agree more. A lot of men can learn a lot from Laura!!! 👏👏👏

[@angeldelcourt6882]

Very impressive Laura. Thank you.

[@kevinforth7618]

Well done - your narration is excellent, thanks for sharing this video.

[@japfourme381]

Excellent video, clear and precise explanations!! Well done!!

[@bobvargas1024]

Many thanks Ms. Garcia for the effort on helping us!!!

[@RobertoSantiagoRodriguez]

Great job, ma'am, very well presented! Wish you could talk to my daughter and tell her is alright for a lady to be a mechanic/auto tech. Thanks again!

[@tpcoachfix]

Great job. If you have a manual transmission, put it in gear to lock the engine. Be sure to set the emergency brake and block the wheels to prevent the vehicle from moving.

[@antoniopalomar1182]

thank you very informative and through. great picture angles

[@pauldavies9464]

Very Clear video, learned a lot very easily helped me make a decision as to buying a tester or sending the car to the garage.

[@danmyers9372]

Very well done!

[@train4905]

Dear laura,an absolutely brilliant video. Very clear,well done.keep up the superb videos.steve from the uk.

[@hellwithit]

Excellent information. Just what I needed. 💪🏼💪🏼

[@jesseanthony3572]

Excellent job explaining every step in the process. Very helpful.

[@richpetrillo8456]

Well done video. Very clear and to the point. Many you tubers can take a lesson from that.

[@evelynedwin2472]

Very informative & educational video. Clearly detailed.

[@axiomaddict]

Thanks for the information. It clarified some concepts.

[@carneasada8695]

Great video, I like how you explained everything.

[@raulbotero982]

Excelente video

[@justdoit8613]

Great job Laura

[@isbcornbinder]

Our shop used to tie a nitrile glove over the exhaust pipe and another over the intake and watch for inflation during the test. Good job, girl. My daughter is a Canadian red seal mechanic.

[@LauraGarcia-yf4xp]

Great idea! I'll share that with my students.

[@jetskijay1955]

Bob Smith I will take note of that!

[@viisteist1363]

you could have a leak in the exhaust pipe too?

[@LauraGarcia-yf4xp]

That is an excellent tip. I may add that to a video in the future. You're daughter sounds amazing. I'd love to hear from her!

[@bobvargas1024]

Bob is the most beautiful name in the world.

[@marybradley1427]

Thank you for the great video. It was informative and concise. I am currently in automotive classes and this really helped. Keep them coming.

[@rafaelchuqui6553]

Great video.... I do like it that way you explained.....you explain a little bit more information than others.... about the .....where the air is scaping...... Thank u.....Chicago.

[@russellnixon9981]

Very well explained clear and simple.

[@train4905]

Very clear and methodical too.

[@mthomefinework]

Congratulations. Excellent explanations.

[@plumbbum2655]

Amazing, I'm working on ase certifications, this is one of the tasks I need to learn and it is learnt

[@shenuhf]

Great information, I will try this tomorrow

[@joekleffner9168]

Very good teacher. well done1

[@bwbdub7218]

you know what you are talking about!! well done

[@dragonmybehind]

Your video is brilliant. The first one I found that described every step and potential issues due to leaks. Thank you and keep making more! I'll be a subscriber for life. 🙏✌🔥

[@abdalrahmanemaish3482]

great video thanks

[@hugo201040]

Hi Laura, I have A Chevy Nova 69, with a GM 250 6 inline Engine, from some reason is very low on power, all cylinder are around 100 psi, I will going to check the Leak Down Cylinder and now with your help I know how to do it , I looked to many videos how to tested but no one explains how the cylinder should be. Thank You!!!

[@JH-tk6ge]

I like Eric the car guy's method of finding TDC, but the oil dipstick idea was cool and new to me. Thanks!

[@metalmike5087]

Can you show how to redo the singing up the ignition with the notches on the crankshaft and the top dead center and the distributor line up on a 1991 madaza b 2600,I series 4x4

[@CHIBA280CRV]

Very informative video thanks for sharing 👍👍👍👍👍

[@podd372]

Thank you, exactly the video I needed.

[@Ali-jm1fl]

Good job.

[@jesussoto5494]

You are the best laura

[@henryalvares7672]

mejor video que muchos otros , me gusto ,no soy mecanico pero aprendi mucho,gracias

[@Ike-yq3gf]

wow, thank you for this.

[@andrewhelmer7710]

Informative video thank you.These leak down tests appear to be mainly carried out on petrol engines . Could you please tell me if the green yellow and red bands would also apply to a diesel engine if the same test were carried out using the appropriate adaptors ?

[@jdmfans6078]

very well explained. 👏👏👏

[@efrainhurtado7024]

Thank you. Nice Video...

[@JoeyArispe]

cool! thank you!

[@germdoesit3795]

Great video can you make a video where you show how you put the engine back to TDC???

[@llewvirtue861]

Good work. Just one thing, once you have connected your shop air, you turn your regulator until the gauge on the rights pointer lines up with the set mark, not 100psi on the left. Anyhow that's how mine works and a few others I have used, maybe snap on is different.

[@Mohy.ly87]

Thanks, that was helpful

[@liviudaniel5082]

nice video ,for diesel leakdown test i can use the same gauges test?

[@ecbmanikandan]

ThankYou For Teaching I Learned aLot..!

[@vin605]

Like the oxygen sensor tip, also you could have a warp or Crack block for the antifreeze to bobble.

[@JuanLopez-vg2uo]

vin

[@japfourme381]

I usually use a balloon over the end. When it starts to inflate you know it’s on the compression stroke!!

[@duniaariechannel746]

I LIKE THOS VIDEO..TQ 4 SHARING

[@johnmilner7603]

If you need 2 hands to turn the motor on a GM 350 even with all the plugs out, attach a balloon to the tip of the quick connect and you'll see when your on the compression stroke. Note: do not connect full 100 psi to the hose in the spark plug. Set that regulator on the gauge to zero then connect it, then open the air slowly to 100 psi. I prefer using a tester that has 2 psi gauges 0-100 or 0-160 psi. I really don't trust that gauge on the right. I made my own and yes I have a .040 orifice hole before the gauge on the right. If your shop air has a hard time providing 100 psi then come down 5 or more psi. Whatever supply psi you use on the left gauge, you can use this formula for your results. It works for any pressure you decide to use on the left gauge, but I wouldn't go lower than the industry std of 60 psi. I'll use 70 psi in and 65 psi for the escaping pressure on the gauge on the right. (70 - 65) / 70 x 100 = 7 Therefore that is 7% loss. The in pressure of 70 psi is used twice in the formula.

[@jayjanyh2932]

In the video the cylinder under test turned because of the 100 psi pushed it and the 2nd gauge went in to the red. Assuming that the cylinder is good... Would the psi on the gauge increase, as she cranks the crank to make the cylinder (being tested) come closer to TDC? Or does the tester have to be removed, before TDC if found?

[@kenhilson786]

That's what I had as a homemade. I just watched a video with a factory tester and prior to hookup to the cylinder he adjusted the regulator until leak gauge was fully clockwise but first gauge only read 20 psi. Faulty tester?

[@Mahigeer1]

Nice video. I particularly liked the oil dipstick trick. I do have some comments if you do not mind. To make sure that you are on TDC (top dead center) you can put the dipstick in the sister cylinder of the engine if accessible. That way while the air hose is in #1 cylinder, the dipstick could be in #4 in a four-cylinder engine. I would however, have the regulator at 0 air pressure and then gradually increase the pressure. Preventing the possible rotation of the crank. On a side note, back in seventies, I was thinking it would be nice to open a repair shop with some female mechanics. Did not happen.

[@bigleo80]

You need to use a “box end” 22 wrench on that particular engine to hold the alternator steady so the engine doesn’t rotate. A ratchet may slip. But you are a very informative female great vid even things I can learn. I’m an ASE master tech/ Toyota MDT and I’ve been in this business all my life and we don’t have enough women like you in this male dominated field.

[@byloyuripka9624]

i dont understand how their sex has anything to so with their work?

[@kyledh772]

More car videos please!!

[@miriamvivo4279]

Muchas gracias 1995 honda odyssey mileage 295 000 timi g belt broke on hwy.

[@gartheligon140]

Here's a trick, put a latex glove over the exhaust pipe and see if it swells up then u got leaking ex valves. Put it on the dip stick tube also. If the spark plug hole is on the side of the head don't use dip stick you can bend it. Use a stiff piece of wire, and keep checking it does no bind before TDC.

[@simonwhite4577]

You remind me of my wife we are both mechanics and our girls both ride motorbikes and understand the mechanical principles of an engine, I personally think ladies explain how things work much better. 🖒

[@RealisticSurvivor]

That O2 sensor tip was really cool. Loadsa guy talking about to listen at the exhaust pipe. But you explained why that isn't a reliable idea. Great job. Muchas gracias.

[@noanyobiseniss7462]

I have stated above why that is a bad idea.

[@mechtech8066]

Simply put the leaking cylinder at TDC then put on the hand or parking brake and put the gearbox into top gear (if manual transmission) that way the cylinder will not move down. Great video way better than Eric the car guy who could not operate a simple air regulator.. go girl..

[@marvinorellanaautoservice4470]

🤣

[@ntblb89]

you can also hear hissing from the next cylinder spark plug as there might be a crack in the head gasket between two cylinders .

[@redwoodepa]

Idk why every person who demonstrated the test is showing the last step the wrong way, the incoming air does not have to be at 100 psi before pluging the gauge to the adapter hose, you do your connections first than gradually increase the psi to prevent piston movement..GOD !!

[@Magnacharger07]

redwoodepa hey little buddy at tdc the Piston doesn't move if it moves you weren't at tdc

[@wcjcnc]

I agree. Most of the leak down test videos on KZbin are wrong. Lol.

[@JH-tk6ge]

haha, thanks redwood

[@casanovaevren]

Sweet

[@ozzstars_cars]

Now I know what an engine looks like. Haha Just kidding Laura, great job with the video! -Glen

[@Sandbag1300]

At 8:18, I believe the thermostat has to be open in order for you to see bubbles from the radiator cap if there is a bad head gasket.

[@consaka1]

Many if not most thermostats have a small bypass hole. Air will go past the thermostat.

[@williamshaw3783]

Water pump will push coolant one direction but air can leak backwards and out the cap with thermostat closed.

[@nationaltruthnetwork5452]

She actually did the test wrong, if you read the info given with these testers, they tell you to test after warming the engine up, so test must be done on hot engine, then all plugs must be removed, reason is when engine is heated everything is properly expanded, and thermostat is now open. Reason for all plugs removed is to test to see if air could be leaking into adjacent cylinder. She did a just ok job, everyone said she did a great job, well she did not. Had she did such a great job your question of the thermostat would have been answered. Also on a cold engine you will have some leakage till cylinders are hot and expanded. She did not tell you to removed all plugs and thus the test for adjacent cylinder leak would not get done. Now perhaps she knew this, but the video was to help and teach others so no well done at all.

[@arcturusbbqsausagemaking2435]

Great video To the point not a lot of bla bla bla Well done..Just subscribed

[@TonyStark-ou8mi]

Great video. Could you tell me how do you stop engine crankshaft rotating plz?

[@Magnacharger07]

Tony Stark when it's at tdc it won't move. once the Piston stops moving you must go slightly further so it's totally vertical and there is no way the lever of the connecting rod can act on the crank. it's tough with short stroke engines but you will get it.

[@TonyStark-ou8mi]

Magnacharger07 thanks a lot

[@Natemasterflex]

Hahaha broken 🖐🏻. Great video 👍🏼

[@kyledh772]

Make more car videos please

[@cRazyfRictioN-dRift]

when you first pressurize the leak down tester the regulator should already be turned all the way counter clockwise.otherwise the set area will not be consistent therefore giving inconsistent readings

[@ironfistarrival]

Hi , what if the problem was more serious and the Cylinder's Rings were not good ? The problem in that case would be a need for a rebuild Engine , right ?

[@JC-kc5jr]

Nice ...............Graciassssssssssssssssssssssssssssss

[@johnlarsen4455]

if the dipstick is at its highest how much do you turn it counterclockwise to get the piston right before tdc

[@billwilliams6338]

LAURA GARCIA 1.) The Actual Compression test kit will measure the PSI level of that No or Low compression cylinder? you will want the PSI level to be 30 PSI or more than 30 PSI to considered a good cylinder? What do you use to test the PSI level of the cylinder? 2.) What do you use to do a Cylinder Leak Down test? You want the Cylinder leakage meter to measure 0% to 20% cylinder air leakage? I have seen technicians poor water on the cars engine to see if the head gasket is leaking or sucking in the water. If the engine starting to running funny misfiring while applying water on the value cover and head gasket this means that its the head gasket or intake value?

[@jantelow]

One cannot find out whether there are worn or broken oil rings by compression and leak down test. Are there any ways to find this out without taking the engine apart.

[@yolisurich4025]

So if it was a piston ring would the engine smoke? Or would the spark plug be fouled with oil?

[@fsilva2296]

Is this test just for gasoline engines or is it also for diesel engines?

[@garykabala]

I think the low range going to 40% is because this is a static test, thus with the engine not running and warmed up with oil lubing the cylinders you will het lower readings

[@garyh30]

Damme homegirl thanks alot

[@mariovazquezcerda7091]

t engo una suburban 2004 5.3 y marca precion baja cuando esta parada y corriendo se le kita el sonido k marc precion baja k sera

[@AcMus1c]

Did you do this cold or hot?

[@jagdishnagar1221]

Nice ❤❤

[@greggreg6975]

How do you fry a piston ring??

[@byronsequeira7483]

Question I'm new trying to learn more about this you have to check each cylinder or just one ?

[@dragonmybehind]

check every cylinder.

[@anidiotinaracingcar4874]

4:49 You're not setting it to 100 PSI, you're setting it to whatever pressure puts the right gauge in the SET zone

[@abbasmuhsen2715]

I do download video helpful for my job

[@67polara]

a far easier method is to divide 720-degrees by the number of cylinders (say 4) and use the timing marks. Exactly matched timing marks would indicate the 1st or 3rd cylinder in the firing order. The other 2 cylinders the marks will be 180 degrees apart or 90 for a V8

[@byloyuripka9624]

flatplane v8s 🤷🏻‍♀️ crossplane i4s 🤷🏻‍♀️

[@alanreyes8370]

Is a leakage and leak down test the same thing ????