How To Perform a Compression Test - EricTheCarGuy

Compression Testing and What You Can Learn From It - EricTheCarGuy
Here is a video on performing a compression test on an engine to assess it's mechanical condition. An engines ability to compress air and fuel is directly proportional to it's performance since an engine is nothing more than an air compressor once you take away all the controls. A compression test is a good general test that will give you an idea of the engine's overall health but it does not give specific information on what the problem is should there be one, for that a "leak down test" would be required, here is a link to that video.
• How To Perform A Leak ...
However if you find yourself looking for the source of a performance problem with an engine, this is a great place to start. This test is often overlooked in favor of looking at the fuel or ignition system, I think that's a mistake, if an engine can't perform mechanically no amount of electronics will make that better.
Recently, I hit the 500 subscriber mark and I'd like to thank all of my subscribers past, present, and hopefully in the future for that. I enjoy making these videos and the fact that you seem to like watching them means a lot to me. So, thanks for subscribing, rating, and commenting, those little contributions make it all worth while.
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Also see the video I did, "Octane Ratings and the 4 Stroke Engine Cycle" for more information on how compression works and why it is important.
• Octane Ratings Explain...
Thanks for watching and stay dirty
ETCG
Due to factors beyond the control of EricTheCarGuy, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. EricTheCarGuy assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. EricTheCarGuy recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of EricTheCarGuy, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not EricTheCarGuy.

[@lightworker303]

I love this "Today I hit 500 subscribers." Today he has 1.5 million!

[@thewjmoneypit7941]

Lol im watching it now 2019 and he’s got 1.3M subscribers

[@forrestl5597]

1.4M

[@movingforward4950]

And me in 2020

[@lshooku]

1.8

[@samthomson3394]

@@lshooku well me mustve lost 400k

[@javiermendoza2994]

Right. Still helpful as hell though. 🤙

[@drenico1]

when I first watched this video almost 12yrs ago, Eric had a couple hundred subs and now he's at 1.6mil subs.. well deserved! Thanks for all you do Eric and the detailed information you provide in all your videos, I'm currently watching it as a refresher.

[@Rob-fx2dw]

Congratulations Eric - you really have contributed to assisting me over the last few years to do work on all of my cars and my family's cars.

[@Stop..carry-on]

I liked Eric's old original honest style in his vids I'd say it's why he's done so well. I remember one Christmas When I discovered Eric's vids I watched the entire back-log ,Now it's all about about product placement and cheap tools .this vid was made when he was a real working mech or had that feel of hand to mouth. How ever the fixing it forward vids are a step in the right direction

[@thatgray24v24]

It's crazy how I come back to use these old videos when he had 500 subs great guy

[@joeman543]

500 subscribers then, 500,000 now. We all appreciate you Eric! Edit: 1.5M now

[@paulert23]

joeman543 and now 614k daym

[@AdilZaman87]

+ROB ANDRETTI 676,238 and growing strong ...

[@NamingGaming]

+Adil Zaman 689,163

[@leo321xda]

+josh mcbride 706,914.....

[@Gregkal123]

+joeman543 721,052 now :D

[@wyatthundley4960]

Now your at 1.1 million and i'm one of them. Thank you Eric for what you do, it has been invaluable to many of us diy'ers.

[@ericthecarguy]

@Yobidefy Actually this test was done on a working engine and the readings on an engine of this kind of mileage is actually pretty typical in my experience.

[@NathansBMWWorkshop]

Good video i might ad that if you have a gauge that has a air hose hookup you can use it to pressurize the cylinder and check for coolant leaks like a cracked head or bad head gasket by looking for bubbles in the radiator by taking off the cap.

[@MightyNib]

This was fun to come back to - you talked about having 500 subs at the beginning, and now you're approaching 2 mil. Thanks for all the help Eric!

[@ericthecarguy]

@1972JasonRS It's not often knock sensors go bad, you might want to check the wiring or the electrical connections one or both could be damaged.

[@ericthecarguy]

@jdmsrv93 I take them all out, makes for more accurate readings in my opinion, that way the other cylinders are not trying to compress while your doing the test.

[@ericthecarguy]

@chronosun13 No, just remove one set of plugs, the easiest ones to get to in my opinion as it doesn't matter which one you remove for the test.

[@harryperrier7223]

Just bought an RB20DET and started learning the mechanical ins and outs of a combustion engine. Thanks very much for these informative videos!

[@carlossoto6623]

One of the best info videos I've ever seen. To the point, and showed the diagnostics on how to perform them. Thanks bud.

[@paulc858]

LOL 500, now you have 1.3 mil! Keep up the great work Eric. Keep en coming. I learn something new every time.

[@stuartsmith5146]

Thank you for saying “why” to do things. Soooo helpful.

[@alexshaw6354]

A million. We're still watching Eric. All the way across the Atlantic in England. Keep it up mate.

[@corywootton8047]

You're the man Eric. Thanks for your help, ive been watching your videos for years, and i appreciate how concise and informative your videos are, always containing your signature amount of dry humor. hahaha

[@meriteman]

You are a brilliant teacher! Keep up the good work

[@ericthecarguy]

@miniwee3 Yes you need to be at WOT when doing the test.

[@ericthecarguy]

@Catass2089 The spark plugs don't make the engine turn over the starter does and yes you would do this same thing on any engine it's just a matter of putting the gauge in to measure the compression.

[@ericthecarguy]

@spiritwolf391 Glad you liked it, thanks for the comment.

[@emirz321]

Great videos, love the detail on each one which is missing from a lot of similar mechanics! Thanks :)

[@ericthecarguy]

@meganerchia Good eye, it was ATF. I just had an abundance of it so I put it in my oil can. ATF is oil with some additives and dye added.

[@baconlover5404]

Should you use a specific ATF for the wet test?

[@edwardstark8377]

1.52m subs now and back then you was happy from 500. Eric i love you bro, seriously.

[@jamessim7074]

Simple , direct with optional ideas of what could be. Thanks it removed all them complicated or not enough info. Thanks again Jim

[@brad8665]

Lol 500 subscriber mark. You're almost at 500,000 now!!

[@MattMohsOutdoors]

500 subs. Now you have over one million

[@michaelserrano7097]

12,000,000 right about now!

[@williamdeleon4736]

Thanks Eric , for your lesson on how to use a compressor tester in wet and dry and explain it on details and organized. I work the same way as you do.

[@ethandenton3393]

You explain things very well. I'm grateful as this is very rare on youtube.

[@TheRagingUnprofessional]

lol 500 subscribers LOL. Watching this now and he has 778k.

[@reggiexp69]

839k

[@michaellhall94]

1,100,874 views

[@mikegillett5881]

where

[@themechanic2500]

Mike Gillett 985k now lmao

[@glennandrews5103]

1 mil niggas

[@B.A.Gondal]

it's a good idea to precisely measure the equal amount of oil for each cylinder for a wet test. This way you won't have to worry about putting more or less oil and gettng wrong readings thus possibly making a really bad decision about the engine.

[@Turboboob]

if you have low compression.... your pulling the engine so it doesnt matter... a wet compression test is to figure out if its rings or valves.. really doesnt matter how much atf you dump in the cylinders

[@mtrott101]

@@Turboboob regular oil or thick stuff for the wet test?

[@Turboboob]

@@mtrott101 5w30/10w30/atf, doesn’t matter. I’ve used it all with the same result.

[@yycforlife5048]

​@@mtrott101 wouldn't you use tge same oil your car takes?

[@ericthecarguy]

@PabloMessier Yes if the spark plug does not seal the opening to the cylinder properly it can cause compression loss.

[@machetekid07]

youve come a long way Eric, thank you for all your help

[@edrobertson466]

Great job on the compression test lesson. Keeping it within common sense and not to technical. Thank you very much. Look forward to seeing more teaching videos. My subject vehicle is a 97 Nissan D21 Hardbody Pickup.

[@GlycerinZ]

dang 500 subscribers. Now you have over 650K.

[@BigDirtyBasterd]

+Glycerin 740k now

[@Mystickneon]

+BigDirtyBasterd 978k

[@MasterKief-fo20]

+Mystickneon 759k now

[@SoyAweonado]

+Peter Cas 782,976 now 23k subs in 1 months wow, thats arround 700 subs per day

[@Michal_1977]

~ 795 k :)

[@jimmorris5700]

Actually my friend you’ve got something that money can’t buy you’ve got a very nice pleasant voice to listen to ! Jim .

[@gerryrodriguez3924]

Thank you, Eric..... I have seen your videos before, however some of the first ones we're too long for me.... So I didn't subscribed, but now I have. Just wanted to say thank you.

[@karatemikepatolino]

I wish you could work on my Honda

[@stab2killnecks]

He makes these videos so you can work on your own honda

[@MrJet30]

lol 500 subs, now i see 1.2M

[@transamturdpolisher4070]

Very good job man! I'm restoring a trans am and with your help I am doing all of my own work. You speak well and explain things in great detail.......I wish all of my teachers in school were in depth. Thumbs up!! Subscribed!!

[@fondeur]

Very nice breakdown Eric. Learned a lot from it and will apply the same steps in my shop. You earned another subscriber.

[@richardsantos1273]

Engine compression test Perfectly described and totally understood! Thank you Eric, now can help me understand my freakin wife?

[@Pfsif]

Just get a new one, not worth fixing it.

[@zaftra]

Shouldn't the engine be to operational temperature?

[@bazthehandyman]

No mate.

[@zaftra]

bazthehandyman Oh right, cool (excuse the pun), save on petrol. Cheers.

[@shokwave23]

Some people would say yes, their argument being that a cold engine has better compression because the elements inside are cold and not expanded. So they recommend warming up the engine to get the metals to expand before checking compression to get a more "true" reading. I've never done a compression test so I can't give my opinion, but the logic seems reasonable.

[@zaftra]

Vincent Gutierrez I did mine warm and they all came out at 14.5 - 15 bar, this is in a 1996 Audi, I'll have to do one cold some day and a 'wet' test to see the difference.

[@shokwave23]

That'd be great! I'm always down for some good science and crunching numbers to clear up car myths haha

[@DavidLunde]

Thank you for this! I recently bought an integra so it was perfect that you also used an integra in this

[@imdifferent2113]

Nice here in 2021 and you're at 1.57M subs congrats and thank you this is timeless information

[@Codyrosa]

lol 500 subs eh? Think you're a little past that now.

[@03vicBlack]

this was in his old shop, from when he began his channel :) just a fyi

[@jesselanyon246]

914,052 from 500 to almost a million, he made it.. lol

[@schrenk]

Going to do a compression test on my '71 MGBGT today for the first time. Thanks for the video.

[@raphialfehr8593]

All the power-mech students in our school are using your videos to learn online, good job mate!

[@MRxPOLSKAx]

How many of the people watching this are subaru guys? -_-

[@ihadalife1177]

Dan_Vallush I'm a 4g63 guy..lol

[@TheNuke95]

Dan_Vallush I'm an rx7 guy

[@stevenswisher4339]

Celica life

[@herbertlofton3588]

Dan_Vallush zoom zoom

[@WahooNo2]

Subaru +1

[@strongmaster]

gotta feel good to look and see the 662,000 subscriber mark coming up. 500 was a proud moment now look, on your way to the gold play button, good job bud.I like all the videos

[@ganeden553]

Awesome~! Great coverage of the whole diagnostics and perspective process. I have a #1 cylinder fail on my Alfa Romeo and was curious what a compression check is for~! Thanks

[@user-sz8tp4zu3n]

Hi Eric. I have a 1973 Ford F100 that is burning a little oil. I have had the valve seals replaced and the burning is still there. I have bought a compression tester and with the help of this video will do the test myself. I do not have an air compressor so I can't do a leak down. Thank you for posting this video and also doing it in an understandable and clear manner for the average person without the foul language that is featured in so many of these videos. Regards, Donald.

[@freeobo85261]

This is by far the best information that I have found, easy to understand, thank you.

[@ericthecarguy]

@orville534 Thank you for that, glad you like them.

[@seangarcia7544]

Hi..Eric i just want to say your videos are a great help for a DIY man like me...thanks for all your help and the videos help me out alot..!!!!

[@orangeshell8]

This was so long ago how far you have come its crazy

[@ericthecarguy]

@Mypringles Yea often the basic mechanical function of the engine is overlooked when dealing with performance issues. Good luck.

[@thedarkener]

This is the second time I've run into your videos searching around. Thank you for making them!

[@0pticalc0ncepts]

Thanks for the detailed info. You really explain it very well.

[@TerenceGardner]

Oh and thanks Eric, I've learned a lot from your videos and your time is much appreciated!

[@pv2smurf]

From 500 subscribers to 1.35million on 9/2019. Rock on ETCG 🤘

[@ericthecarguy]

@chamblizi I would fix the oil leak first and check the oil pressure with an analog gauge to see what pressure you really have, if the engine has noise AND low oil pressure it may be time for a rebuild or replacement.

[@anthonysilva5015]

about to inspect a boat tomorrow, thanks for the insight!

[@precool]

Hey thanks for the educational video my friend. Relevant to me right now because I'm having a new head put on my MINI Cooper S. Two very toasted valves, and my plugs looked even worse than what you had right there. Excited to be back on the road soon, with more knowledge thanks to you!

[@ericthecarguy]

@chamblizi You might want to recheck those oil numbers from what I remember it was either 10W 30 or 10W40 that those things used but even so you might have an oil consumption problem. As for the hard starting it might have nothing to do with the compression but perhaps a carburetor issue. As for the leaking sensor I'm not sure but it could be the oil pressure sensor.

[@toddcott9510]

Can't fault this video, you seem to have covered everything. Just wish every mechanic was up to your standard. Many thanks.

[@mmmmtastyful]

i'v been watching these vid's for over a year and i just have to say ''you frickin rock dude"" you have answered tons of my questions and i have a special playlist on my you tube act. just for you man. thanks again man

[@jblai05]

Best video ever. You are an excellent, logical teacher, Eric, and videography is some of the best. KZbin = crystallized knowledge. My father, a mechanical assembler/mechanic asks me how I know this stuff. I tell him, "I am the Smart son..." Thanks again!

[@audreycathrine]

great info eric . thank you . going out to try it on my 1966 mustang .

[@AdamGen88]

awsome vids bro, learning lots from you, currently rebuilding a 4g63 for my talon, fairly new to engine building. you cover alot more of basic stuff but hell I know what to do when I first want to start my rebuild thanks to another vid of yours, keep doing what you doing. subbed.

[@NC_1_SIC_Impala]

Great video, Thanks. I just purchased a 1960 Chevy Impala with a 348ci. I'm having major issues with 4 cylinders oiling up and fouling plugs. I replaced the points and went with a hotter coil and Petronix I ignition. No change. The old coil was 55 years old! There's three cylinders next to each other on the drivers side and one on the passenger that are doing this. I'm thinking on the compression test next and removing the heads to check out the gaskets.

[@thomasjackson4465]

Thank you for the info and the video got a 2005 Tacoma I’m working on atm. I thought it was the initially the head gasket but I’ll have to do further research

[@MrTonyBrooklyn]

Love watching your video's. Clear precise information in laymans terms!

[@thatsdaniellelol]

Man thank you so much for that info about the pistons being offset and for explaining you how to always know where cylinder 1 is on a V shaped engine. I never knew about that one! Now I just have to figure out how to always know which is bank 1 vs bank 2. It seems like each manufacturer is different with that

[@sunny2237]

wow, great vid, that's so informative. especially when you were talking about the 1st cylinder on V engines. I didnt notice that, short sweet and to the point.

[@ActiveDadsRule]

From 500 to 1.7 million subs in 10 years. Love and appreciate your channel sir.

[@bmorain]

I was looking for information on doing a compression test on the exact car you featured in this video! Love my CR-V but it needs some help, thank you for a great video!

[@ericthecarguy]

@vatan1923 No but some have glow plugs that you can remove and do the test in the same way, with others you might be able to remove the injectors to insert the tool to do the test with the correct adapters.

[@Rowan777]

Great video, your explanation was simple and to the point.

[@acek100]

i learn so much watch all ur vids.. yes all. im addicted to engines and mechanical devices.. thanx for all the info bud.

[@michaelw6277]

Congrats on 500 subscribers!!! Have a cake!

[@soapsoilandsunshine3241]

Love the opening comment. Hit the 500 subscriber mark. Weeelll, you must be doin' something right. It's 1.66M now. Well done.

[@garymahon1955]

Very good presentation Eric.

[@captainrandom6858]

Congrats on 500 subscribers Eric!

[@SuperLostvegas]

Eric, thank you very much for this video. It was very helpful.

[@playstationRLZ]

500 a little over 3 years ago. now he's at around 150,000. congratulations man!

[@lavalois09]

Great video! Im doing some last minute revision before my engines test at school.

[@andrewhudson3723]

After all these years, still a great video

[@timklein3962]

GREAT video; you cover all the bases; thanks !!

[@cesargarduno7999]

Thank you Eric well explained and the reasons why, excellent video thanks for the help.

[@JonLasaga]

amazing videos throughout the years eric thanks for that

[@mikerobertson1781]

Great video Eric.Now at more than 1.6m subs and well deserved.

[@sarasotauptoseattle]

Very well done. Common sense approach and good info w/o stupid flare or click bait. Thanks.

[@yasinkariem3347]

I'm watching this and you have 1.67 million subscribers... very good to see this 👏 hard work

[@ericthecarguy]

@PabloMessier You don't need a scan tool to do this test just the tool shown in the video.

[@nicolasporta2007]

thanks man! your videos are very helpful, im gonna check my motorcycle engine compression right now, tanksss