No Compression in Cylinder No. 4 (blown engine?)
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- Опубліковано 10 лют 2025
- No compression in cylinder #4! This isn’t good...Join me for a quick tutorial on using a compression tester on a Subaru engine and I'll fire up this engine to see how well it actually runs with near zero compression in cylinder #4. In the second half of the video, I discuss THREE fundamental ways an internal combustion engine can loose compression and what the next steps are for my EJ205 2.0L turbo engine.
LINK TO OTC COMPRESSION TESTER:
www.amazon.com...
This video is part of a "Build Series" (see "Playlists" tab for all videos) for my 1998 Rally Blue Pearl RSTi Coupe (Impreza 2.5RS swapped with a EJ205 turbo engine), which is 1 of only 720 sold in the USDM for 1998. This RSTi Build has come a long way and includes a full archive of videos documenting how to: (1) Pull a EJ-series turbo engine, (2) Replace the head gaskets, (3) Add key upgrades to increase long-term reliability, and (4) Restore the interior to OEM specifications.
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This is an awesome channel. I’ve learned more about Subarus here than anywhere else. And you seem like a pro so I can trust what you say.
Thank you man!!! Means a lot. Cheers and hope you stick around for more!!! I got plans man...
I had this happen to my 2002 WRX a few weeks ago. She lasted a good amount at over 272k+ miles. Going with the IAG 600 long block!! Going to restore all the parts and powder coat parts myself in house!
Sweet build plans man!!! And hell yea, you got some miles out of that engine! 👌
Man, that's really unfortunate but I know you'll build it back up better than ever! Looking forward to the rebuild Luke!
Thanks man, and you got it 100% right. Always planned the replace this engine, now the timeline is pushed up - which is actually a good thing in the long run. Cheers and thanks!
2006 Subaru sti po302 did plug and coil swap, vacuum leak check with smoke machine. Checkrd a/f ratio sensor cleaned and tested for ohm specs and voltage with heat. Next is injector swap then leakdown test with otc kit
I love my OTC compression tester. Feels very high quality and works great! Bummer about the engine. Unfortunately going to guess ring land. Best of luck!
Thanks man! Just pushes up the timeline! 👍
I have a similar issue with an unrelated engine. It happened suddenly while driving: losso of power, flashing check engine light and ECU complained about cylinder 2 misfire. However, the garage said it was lack of compression in cylinder 4. Also starts well and idles fine.
Hey Luke, uncannily smooth, has to be due H4 config. I had a 1.2L Alfasud, also a horizontally opposed four banger, it got smoother the more you revved it. But was produced with a symmetrical exhaust manifold - no rumble, just Italian rort and rasp My musical sensitivity told me that the Subi-rumble was down to exhaust phasing, the first time I heard it was in the 90s. I have only found out that I was right, a couple of years ago. Subi rumble - I like (now).
Very cool to see this condition - when it is someone else's problem (thanks).
Haha. Love it. Cheers buddy!!!
Cant wait to what it is! I have a "similar issue" where i rebuilt my sb after spinning a bearing and now i have 95 psi in cyl 4 and 119 in cyl 2. shortblock also has forged pistons and rods as well as arp head studs. Guess ill have to tear it open and see. oh and leakdown on cyl 4 was 20%
Thanks man, appreciate the support! I’m excited to see what the heck this is too!
Brilliant video mate thanks for sharing, my sti dip stick smells of fuel I've been told that is worn piston rings or leaking injector, I hope it's the injector, thanks mate
Thanks for the video. Just subscribed. Same issue on my 99 forester. Cylinder 4 no compression. Still runs great down the interstate. Lots of lost power starting from stop though. Deciding what to do next... Would like to upgrade power from stock ej25. Do you know of any engine swap upgrades. Probably buy a service manual from your website too. Thanks again.
This is my fourth car in a row that I have bought and I was unable to drive it more than a couple weeks
That sucks..... I'm doing an EJ255 now with a melted piston where they let the ringland failure go for a while. Aluminum splatter lining the cylinder wall.
I love my OTC tools. Never had an issue. I have their compression, fuel pressure and leak down test kits (in addition to other tools). The leak down tester is great at identifying the major source of the leak.
Thanks man. Both in the same boat, haha. Cheers!!! 👊
Props on the build tho! Everything looks and sounds amazing!
Ah thanks man. Gonna look even better now!!!
I have similar issue with my 2.0 DOHC EJ. Cyl. 3 has 90 psi and others have 130 psi though it runs REALLY rough on idle and the whole car is jerking and trembling. Any ideas on why that is?
Sounds like you know what you have with a used engine, unknown milage, raced. At least you got some use out of it. Now it might be time for a rebuild, we will see after the leak down test, I would love to see you rebuild the short block on the channel ☮️
Yes, it’s definitely a “used” short block. Plus there’s even more carnage to the backstory, stay tuned, more on this! Cheers and thanks for the support!
Oh and yes, maybe I’ll do a shortblock build in the future, not an expert. But what the hell, I’m not an expert in anything and that never stopped me.
What about doing a wet compression test just to compare results? Also, I would like to see results of the leak down before ruling out valve issues because I have seen a number of exhaust valves that tighten up after rebuild.
OTC tools are really good quality on most things too.
Yes, will do the leak down first thing. My be tight valve, that would be nice!!! 😉
OTC makes nice tools. That compression tester is $53.32 off right now.
That’s a smoking deal. Nice!
Beautiful build, really sucks you got this far and now have to pull the engine. Oh well that a project car, always tinkering, and never finished.
So true. Always was a potential. Now just pushing up the timeline! 😉
At the beginning of the video when you ran the test did you hold the gas pedal all the way down to cut off fuel? Or did you remove the relay/ fuse
Yes, pulled the replay.
Hi man love the show
Hello, Thanks so much for posting your very informative videos. PLEASE HELP!!! I will start with the question I am hoping you can answer, explain the backstory and end with the same question to keep things organized. I genuinely appreciate any advice and feedback you can offer. Do you think it is possible for a rodent nest (10"x6" mind you!!) to cause no compression in cylinder 5? I have an expensive problem on my hands. I was driving my 2015 Toyota Highlander (102, 000 miles well maintained with proof of service) it started shaking and check engine light, Check all wheel drive and check traction lights came on. Brought it to our local mechanic and they found a rodent nest on the engine (engine bay I believe), upon further inspection they found that cylinder 5 had no compression, but they weren't exactly sure why and suggested we take it to the Toyota dealership for additional diagnostic. They found the same issue (still don't know why, but they don't seem to think it could be rodent related, but again aren't certain what caused the issue). Because there is no other reason given, do you think it is possible that it could be rodent related? It just seems very coincidental, but because I don't know enough about cars it is hard for me to prove although I am trying to dig up what I can and found you :) Toyota and the insurance company didn't see any obvious wire chews so they closed my claim saying it must be "wear and tear" except I have our steady service records and the mileage is less than a standard lease contract- we have a 2010 Rav 4 with 30,000 more miles that is serviced the same and is running great- the mechanics said this is "very rare for a 2015 Toyota" and said I essentially got the short stick and that cars break, and now I was forced to replace the engine as the only solution ($8,200 +450 in diagnostic fees). Toyota was hoping they would find an actual reason (and of course I was hoping it was rodent related as it would be covered by insurance), but they took out the engine and still have no distinct reason for the engine failure/ cylinder misfire, but said maybe it could be debris that made it way into the engine somehow or a mechanical issue (broken arm??). Anyway because that differs from chewed wires, I reopened the claim thinking it could potentially be nest material (there was lots of material) or mouse food "debris"- there just isn't another explanation at this point. My family has been without our vehicle for almost 1 month and it has really made our lives difficult. Anyway, sorry for the long story, but the insurance company is sending out a "engine expert" tomorrow morning to look at the engine and prob try to disprove that it could be rodent related and it feels like it is my last chance to make a connection and prove that it is possible. I found some articles that say maybe an issue or obstruction in the intake?/ debris somehow getting by the air filter and clogging or making its way into the cylinder?/ debris getting sucked into the air filter then the intake (intake runners or intake manifold)?/ Debris getting caught in the valve train preventing the valves from closing causing no compression?/ a block in the throttle plates??/ Issue with the knock sensor injector?? I will ask more questions tomorrow, do you have any advice on how the rodent nest could have caused no compression in cylinder 5? Thank you in advance, Kristin
Hi mate, im currently trying to purchase a 2010 WRX, we did a compression test on the engine (it was cold, and we didn't use wide open throttle). Cylinders 1, 3, and 4 all had compression at 135-140, while cylinder 2 compression showed 120. Is this a concerning sign? Should we redo the compression test hot and WOT or skip it and try to convince the seller to do a leakdown test on it before I buy? Thanks!!
Don’t know why we didn’t do a compression test the motor WAS just put in new from Sunwest performance short block and single piped the kid put over 15,000 in this motor and I bought it and had issues immediately after purchase car ran super good on the test drive but ran completely different after transaction a week later it’s 2004 Subaru Impreza WRX 2.0 and I changed the MAF sensor and some oxygen sensors and I tried taking it down the road and it blew up
I just rewatched the video. It looked like it wasn’t holding any pressure. You double check if the test was fully teighted
Yes, redid the test a couple of times. Def holds no compression.
Sounds sweet muy bueno. Valves , ringland failure?
Yes, one of those for sure!
Thank you Luke.
I have similar problem on STI , one cylinder near zero compression, slow off mark, engine shakes at idle, but still goes well, still kills WRXs (maybe the power comes from the turbo that's why 2.0 and 2.5L engineer new not much different in performance? I think it's bent valve situation, I don't know how, also has already slight bearing knock, ( maybe extra play in rod has caused piston to hit valve? One theory), You can hear that one piston is low on compression when you crank engine too.
I should do a leak down test. Can't wait to see how to do it. Looking forward to next video on that subject
I'm wondering if you sell the OBII engine check scanners.or have any recommendations?
Could you please show us how to use? Also do you know how tune / remapping? Any recommendations?
Hi. Thanks for the support buddy! Yes, leak down test next. No, I don’t have any experience doing tunes myself. For the OBDII reader, check to the “Subaru Tools” section of my Amazon shop. Cheers!
Hey man I have a caddilac it has low compression in cylinder 5 but it does have compression but iam getting a flashing check engine what are your thoughts?
I have the same problem in my Subie
2007 legacy 2.5 turbo
No compression cylinder #4
Can somebody fix 😥
I don’t wanna replace the engine
166 K
I feel ya!!! We’re in the same 🚣 😂
Possible burnt valve. Id check for that after leak down test
Yes, will do for sure man!!
Hadn't watched the full video yet when I made that comment, so I heard after the fact you did the valve work and all.
You can also squirt some oil down the #4 spark plug hole and do another compression test (warm) if you get the jump in Psi that would lead you to piston rings. (I'm sure you know all this but been in this same boat a few times with my subies) still thinking it could be chipped valve. Will be waiting to hear what it is!
Also when doing leak down, get a nice big ratchet on the crank and see if you can nail down the #4 exhaust stroke and intake stroke for valves. If they both yield the same leak down % prob not a valve! GL!
Thanks man, much appreciated. Keep it coming! 👍
Great vid. Thx. Off topic but can u recommend a uel header for a gc8 non turbo thats not crazy expensive?
Not off the top of my head. And thanks!!!
I'm going with jumped time and a bent #4cyl exhaust valve if it isnt popping through the intake. Either that or the valve is just burnt and sticking.
Nice call... we’ll see. Leak down tomorrow (freaking rained cats and dogs today). Stay tuned!
Hi, I have compression loss after the engine is hot, one cyl/bal has only 0.64,,1.8 tdci Ford engine,tested with forscan ,,any idea
All depends where you are loosing compression. My advice is to do a leakdown test and go from there.
@@SubaruONLY ok, thank you
Look at sunwest automotive engine in Washington. I’ve purchased two Subaru short blocks from them. Come with a warranty. $1500
Nice. Thanks man!!!
With a compression tester it won’t lose pressure. Once it hits a number it will hold it until the release valve pressed. A leak down tester will leak down because it doesn’t have a Schrader valve but I would retry on another cylinder before saying anything is dead.
Umm...that’s all true for a compression tester, but you forgot about the engine! 😂😂😂
I’ll stay tuned. I just know a misfire cel is caused by so many misfires within so many rotations of the engine. It can be caused by wiring, injectors, plugs, or coils. Just seems very strange the cylinder is bumping to 30 psi and then totally gone. Like an issue with the compression tester leaking either at the quick connect, the schrader valve or the release button. The leak down test in a normal situation would be correct but if that compression tester is seeing any pressure it would start at that point.
Not an issues with the compression tester. What your seeing is what it looks like when the rings, gaskets or valves leak slightly. FYI.
Damn. Sorry to hear about the compression test. Bent valves, cracks in the journals? Or do you think it might be the piston rod? Edit: Just finished the vid where you ruled out a number of those.
Not 100% sure what it is. But should have a better idea in the next day or two. Thinking rings, there’s a little more to the backstory, stay tuned on that!!!
@@SubaruONLY looking forward to it!
👊
Other than the obvious check engine light how did it drive with zero compression on cylinder 4? Was it terribly obvious or just didn’t feel quite right?
Not too obvious, tbh. More like didn’t feel quite right.
I have a 05 Xt with 0 compression in cylinder 2 , idles not the best , but once moving over 1200 rpm it’s like nothings wrong … full boost stage 2 tune downpipe . I wanna say intake valve stuck ?
My #4 failed. Ringlands. after rebuilding a number of Subaru EJ25 i washed my hands of them. PIA and they never run the same after a HG failure or anything major. Just end up throwing part after part at them. As they fail continuously.
Ahhh that’s rough man. Get an LS?
Toyota and honda way ahead on engine reliability
👍
A so I have a p0546 got the car with a bad turbo new g20 turbo and can get rid of this code
Not sponsored yet you have a link to purchase from your store...hahaha😂😂😂😂
I poured everything I had and I lost my job because I couldn’t get back to work and now I have a 2004 lemon with no money on hand
Are you going to try get a V7 EJ207 short engine? and use original heads?
The v7 207 is a stout engine
Nailed one of the top options I’m considering. Exactly man 👌 ! Use the short block an EJ205 heads and new OEM 2002 ECU for BAR and all the legal stuff. Then pull it back out, swap back in the 207 upper end and ECU and be on my way!!!! 😉
Time for a leak down test
Yep! 👌
Ej207 time? Would be nasty with the addition of avcs!
Hell yea!!! 👊
Does it boost hard and accelerate fast still?
Or feels gutless?
Made decent boost, but it’s a stock tune OEM engine, so that’s not all that much.
I am so so messed up in the head today i can’t even function.
Not sure what to do
Man this hits home. Lost compression in cylinder 4 two days ago. I suspect it's valvetrain related.
That’s some crazy timing. Small world man.
Taking heads off and not do a bottom end that was very bad move. I knew it that will happebd from a day when u dine a video with your plans you gonna be do just a heads rebuild. Plenty of ppl learn the same on own mistakes. Anyway good luck with rebuild and I'll wait for next episodes.
Thanks, kinda of....
My Subaru doesn’t overheat but feels like it builds up a lot of pressure
How’s it behave under load is what I want to know
Drives decently. Bit of smoke.
That was just a dry compression test? Why no wet compression test?
Did it on a warm engine too. Same issue.
Wait a minute, did you retro fit a illuminated key bezel ?
Hahah, good eye man. Adapted the entire ‘05 WRX steering column, couple trim pieces to massage but otherwise, it’s a super clean OEM looking install! 😉
Ditto zero compression in cylinder 4
leak down test up next as I planned
How did it drive like that ? Apart from being under powered, cheers keep up good work
Drove so so. Didn’t hesitate or miss or anything. Just under powered and didn’t spoil up fast as it should.
@@SubaruONLY only ask as ive an 07 sti hawkeye and last 6 months shes got a strange surge feeling at very light throttle inputs only between 1900rpm to 2400rpm (dbw) thinking its in tune now as tryed everything apart from compression test but no really under powered under wot, seems in lower rev range, any help would be much apriciated, thanks
I thought you check the engine before you started doing the stuff to it???
Had a blown head gasket, can’t verify compression until the head gasket is replaced.
That much blowby (you have almost 0 compression)... i think you would see when you took of the heads.
I think that must be a stuck valve.
Might be. We’ll see. Stay tuned.
Might be a silly question, but would you be able to diagnose this via an access port? Not the exact cylinder just that one has decreased compression.
Thanks!
No. Access port would only tell you the check engine codes and allow you to monitor live data streams - no sensors monitor compression, you’d end up having a misfire code, which is the result of the low compression.
@@SubaruONLY thanks man. I dig the videos and your communicativeness. Subscribed
Thanks man. Appreciate the kind words. Cheers 👊
EJ207 Short block,factory forged internals. Such a shame.
This is a 205
I know! It was a helpful suggestion. But if I were going to replace the block then replace it with a bolt up the same better part that cost bugger all more.
@@gen3v8 the why you typed it sounded like you though it was a shame that the block was a v7 and blow up
Yes!!! 👌👌👌
@@jeff666p All good wolfy,. It was bad luck though will all his work so far
150 psi is warm pressure. Pressure when cold is lower. Didn't you rebuild the engine
Good call. No, short block is original OEM one from a 2005 WRX, no idea how many miles.
Do a leak down test.
It'll tell you exactly where the leak is.
Yes agree. Stay tuned. 👍
$50 bucks on ringland failure
What kind of exhaust is it on the vehicle?
Stock downpipe. Aftermarket muffler - not sure what brand. Magnaflow maybe!
Shame m8, I've been there myself!
Thanks man. Just pushed up the timeline, noting wrong with that! 😁
Just pull the engine already. Takes literally 2 hours not even to yank that piggy out. You'll want to keep an engine hoist and engine stand in your garage when owning a Subaru.
Hahah true. But I gotta make these videos too, litterally makes it take 3x longer, lol. 😂
Time the a leak down test... sorry man. That stinks, the car was so close to being finished
Thanks man. It’s still close! Gonna do this short block swap quickly!!!
Sucks:( but it’s just more videos to make! More money! How about that
Haha. Thanks man. Feel like I could make plenty of videos with a perfect running car too... lol. All good and will give me the opportunity to knock some other things out.
@@SubaruONLY I appreciate the reply! I’m definitely waiting for the leak down test video. I’m building a na/t 99 legacy outback and currently working out bugs and your videos help out allot! I’m thankful for the quality and work put into your channel! Your cylinder 4 cooling mod video is one of the ones in my playlist to make my car better! Thanks again for the content! Awesome stuff!
Thanks man! It’s great to hear these videos help people and this whole “making videos” thing was totally a random unexpected thing I never thought I’d end up doing, but it turns out I like the whole process a lot, plus now I’m meeting all kinds of cool people (like you!) that I never would have met with my normal day job and local circle of friends, so this whole YT thing is pretty amazing actually. Thanks for the support - cheers! 👊
Probably a bad valve
My guess too. That’s why it runs fairly well on the road. When the engine reaches operating temp the valve releases. Just a guess from an idiot. 🧐
Just heard the previous guy had a “big turbo “ changing my guess to ringland
Yep, very possibly. The leak down will tell all!!!
A 10 minute video to show a compression gauge registering zero compression. What a waste of time. This should be a 25 second video
Harsh man. But fair enough…
Subarus are horrible platforms. Absolutely horrible.
They can be. But they can be good too. Cheers!!!
I never undertand what you fix
What ? You do before put the battery
I poured everything I had and I lost my job because I couldn’t get back to work and now I have a 2004 lemon with no money on hand