Watch And Listen How A Subaru Engine Rod Knock Vs Piston Slap Sounds Like
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- เผยแพร่เมื่อ 31 ต.ค. 2023
- Difference between a Subaru engine rod knock vs who a piston slap (which is minor) sounds like. They sound similar but very are very different.
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The New York accent shined through over that rod knock 👍 best comparison video online. thank you!
Glad you liked it!
You forgot to rev the engine knock so we can hear the difference.
Thanks for the video!! My Honda B20 has some bottom end tapping when the coolant is warmed up enough for the idle rpm to drop lower but the oil and metal isn’t very warm yet, and I was 98% sure it was piston slap (fairly common on the B series engines) because its never complained about me wrapping it out to 7000+ rpm, and this confirmed that and put my rod knock fears aside. Thanks!
Thank you for the comment. Yep seems like that to me too from what you explained.
Thank you Sir. I was able to identify the rod knock in a 2016 Kia at the used car lot. Didn't buy the car, of course, thanks to your video.
That’s great and exactly what I like to hear. No body getting scammed!
Thanks for the efforts
My pleasure, and much appreciated
Thank you for showing both! I don't have a Subaru but my Sebring is making a similar noise (210k miles) to the piston knock. Hopefully that's what it is but I guess I'll find out LOL
Good luck!
excellent video
Thank you very much!
Good video. I just seized my 2008 Subaru Impreza 2.0 engine completely. The mechanic had just a quick look because it was not worth it to do a full inspection but he thought the crankshaft cracked. It made the knocking sound as well before it seized. It already used excessive amounts of oil for months. Fixing it would break the bank so I'll bring it to the scrapyard.
Thank you! Sorry to hear that, if the vehicle is worth fixing, i have videos on rebuilding or replacing engine.
This is exactly right. I just built a 2008 2.5 SOHC engine using a good 2001 block and crank. Good used 2008 rods and new 2008 pistons. I put new rod bearings in but couldn’t get a good set of main bearings anywhere so I opted to use the old ones that were in very good shape. I plasti gauged all the bearings and they were all perfectly in spec. The wrist pins to small rod end were perfectly in spec. The new pistons had about 8 thou of piston to bore clearance which was a ways out of spec but I decided to give it a go since the ring end gap was good. The heads are rebuilt and surfaced. Anyway, what I’m getting at, is it had a small knock like the first example but not near as loud and it worried me but I know for sure it couldn’t have been rods because I went through all them. I know the pistons were sloppy so that’s gotta be what it is. Goes away when warm or when reved.
Yep, exactly right!
Picked up a rust-free 2006 Impreza 2.5i 6 months ago for my son. It had a rattle on start-up, and some noises, classic Subaru, they're all I drive. Now, he is gone all the time and I see and hear it infrequently. But when I heard it idle at times, I thought it sounded worse. I changed the oil, but no change in sound. I had access to the car just after Christmas and the loud tapping/knocking occurred in the following cycle:
Distinct at idle, increased upon accellerating, then gone while cruising along. When letting off the gas to coast approaching a stop sign, the noise returns when it gets to 25 mph > idle.
The local Subaru specialist had it today for some other things, and he checked the sound, confirmed no exhaust leaks, and suggested rod knock. When I drove it home, I wasn't sure if I'm now oversensitive or if the symptoms described were far more pronounced. Never had this with any of my Subaru's. Any opinions?
From what you’re describing it’s not really going away when fully hot so it’s probably a rod letting go. You can try to put some oil treatment like STP in there just to see if it gets more quiet,if it does then the rod bearings are failing.
@@MotorcarnutThanks for responding. I like my Subaru specialist mechanic, but we seem to have communication issues. Long story short, this knocking sound was apparently "quite pronounced" at the shop yesterday (and when I drove home, he was right, it was much worse than when I drove it there the day before.) I changed the oil last night and ran a big magnet around, and there was some tiny metal bits, but nothing dramatic.
The "communication issue" I referred to was a chat a couple months ago when he believed a coolant leak was my HG...but it was the radiator. It has not overheated at all. But he recommended yesterday new block and heads, citing "danger" the heads may have warped from overheating "at some point". I could order a long block...would save the machine work the shop would do...but it comes with a new timing belt kit, which means losing the money I just invested 24 hours ago. I should also note this guy lost his long-time machinist that did block/head surfaces...but he "could find someone" to do it. But again, he's rather hung up on the "get new heads" advice.
So is there any reason to bit the bullet and just get a long block? (Maybe I could arrange a long block w/o a timing belt kit...but doubt that's possible because most engine shops pre-run the engine before shipping it out.) Thanks for the advice...dealt with so many thinigs but this (especially with a non-turbo) is all new to me.
@tomasx9027 If the car is worth it to you and makes sense money wise a long block would be the best bet, less labor to rebuild your old one and should come with a warranty. Timing kit you have just keep it as a spare.
Or just throw so new bearings in UT if the cranks isn't chewed up to much.
Great video, my suggestion would have been to add the valve tick noise for the third option of what a lot of Subaru owners hear
I’ll make one of those when i get one in.
I have a 2023 Crosstrek with a 2.0 liter motor, with 20,000 miles on it and it runs like a top, and the motor is about as noisy as a top! Those 2.5 liter engines can start ticking and making other engine noises shortly after purchase, and most will eventually become noisy. If you want the little extra horsepower and torque that the 2.5 liter offers, you might have to tolerate some annoying engine noise(s) for the life of the vehicle. Not worth it! My 2.0 liter has 20,000 miles and is super quiet, even on start up. I'll take the smaller, quiet 2.0 liter motor, over the bigger, junky sounding 2.5 liter motor any day.
@Kragum24 yours will make noise soon too. They all do at some point.
Yep, I always have loved an engine that will blow up very quietly😆👌
Depends, engine knock, yes but piston slap could go on for years on Subarus with not problems.
Bought a 2015 legacy 2.5i a little over a year ago. Bought it at 108000 now has 145000. Engine gets a little loud when cold starting. Michigan weather for reference. Obviously cars hate cold weather but hearing what a problematic boxer sounds like helps a lot. Now i know what to look for in case something is actually wrong. That being said, these engines are noisy for a 4 cylinder
Yes, they are. I don’t like it as a mechanic but had many over the years and were very reliable.
Alright now stuntman hold her to the boards and get to it! LOL
thanks brother i thought it was knock 😂😫
No problem 👍 Glad it helped!
I've got a tapping sound on my 2006 scion tc that starts at 2000 rpms, and disappears when I go higher. A friend said it's probably rod knock. Doesn't make any noise until 2000 rpm.
Very well can be that would be a symptom.
my first car was burning oil and i had no idea, so one day my engine exploded on the highway, and it was very loud knocking sound. now 10 years later, im facing a problem with my hyundai kona 2020 burning oil, keep adding more every few days
Those engines are under a recall for free replacement you may want to contact Hyundai
My 15 Legacy is nice and quiet with 125,000 miles on it. My wifes 18 Legacy with 70,000 is loud. I treat them the same except, I take the time to warm up the engine, she doesn’t. People say warming up an engine is useless?
No it's not, As I explained in another video and you are experiencing, some Subarus make noise some don't but considered normal. Warming it up is key to longevity either if it makes noise or doesn't.
Thank you so much for helping me distinguish what an engine knock sounds like - and what a Subaru engine sounds like hahaha.
Glad to help!
Tengo un Subaru Impreza sport 2017, es normal que cuando lo encienda este acelerado y luego se normalize?
When you first start it, it is normal for rpms to raise a little if it’s too much the throttle body may need to be cleaned. I have a video on that too
Mine is odd its got a new rebuilt engine its quiet when cold then when it warms up it has a small knocking noise but only at idle if u give it any kind of throttle it goes quiet again
Normal
Nice video ! Will Piston Slap / Rod Knock make your car shaking a bit? Are there more hints that can help distinguishing them?
Yes it will. Piston slap is twice as fast as rod knock
@@Motorcarnut You are so helpful! What do you think about this noise? Planning to do a full check later this year, and i hope this is not some serious problem
th-cam.com/users/shortsb-_rA-0jx3M
i had this sound when knocking can be heard when accelerating especially at low rpm but not at idle. Any idea?
If it doesn't go away when hot, it's either a rod going or excessive piston slap.
Anyway to fix , either or both .. with engine additives .. engine restore
Unfortunately no.
Mine (04 Yukon )sounded just like that my starter went out just replaced it today when to boost the battery crank revved it a bit and I heard crackling noises and the engine died ! 😭
Sounds like it just seized up
My Subaru sounds like the second one when it starts up and is very loud, however after it warms up it sounds pretty normal 95% reduction, I can hear a little when I give it higher Rpm’s but with windows up can’t hear a thing. Would this still be piston slap since it goes away when warm?
Yes it would
It’s likely what your hearing is your valves ticking. This is also very common with Subarus
What’s worse to have. And is piston slap something you have to address right away.
Engine knock is much worse. Piston slap that goes away when vehicle is hot can last the lifetime of the vehicle. Piston slap that doesn't go away after warm should be addressed sooner than later.
Thats the subaru swag
Yep
If it was a rod knock would the
Engine light be on? My engine light is not on and I’m up to date with oil changes. I’m just still having trouble hearing the difference between the two
No it doesn’t have to be on. If the noise goes away when warm it’s piston slap if not it’s a rod knock.
hey how are you, I have a big problem, I have a Subaru Forester 2009, I just changed the head gasket and put it back together everything, I know everything is connected but my car doesn't run, the car has a crank, but I listen the pistons hitting the heads, and I don't know waths is going on, can you help me whit this
THANK YOU SO MUCH
Sounds like the valve timing is off. Their isn't any other way the pistons will hit the valves unless it is off.
I have a knock on 3000rpm only sti 2004 with a lot of power loss but no knock whn idle any idea ?
Sounds like pistons are failing
With rod knock, engine speed with changes the rate but not the intensity.
Depends on the severity of the knock.
Is Rod knock present at start of a vehicle? Can the knock noise come and go? I have a knock that isn’t consistent and comes and goes away
You have probably piston slap
Hi brtoher i have bmw the same noise you said piston slap came out in it....and the oil temperature is not normal its low when i visit garage they said to me its engine rod knocking sound from down but its not sound like rod knock not even near to that sound what can i do any advice ...thanks
Post a video of the noise on your channel and I can give a listen
Ok i will posted it soon
If the knocking is quieter, is it not rod knock?
I've had my engine go low on oil (dipstick completely dry) a few times.
But it's fairly quiet and only occurs at around 1,500 RPM.
Unfortunately it can still be a rod knock just not the bad yet.
It’s Definetly a big end gone (connecting rod bearing) engine is toast. Replace itl just get worse.
@@shawntee1859 fear-mongering for no reason. Chill out.
Que problema tenia ese motor ??
Donde estaba el problema
This was a demonstration. The engine with the rod knock needs to be replaced or rebuilt. The piston slap doesn’t require anything unless it doesn’t go away when fully warmed up.
What’s an easy way to get rid of a engine rod knock?
No easy way outside of rebuilding the engine.
Could I send you a video of my vehicle some how to see what it is I can’t tell
Yes, post it on your channel and let me know
There was a knocking on my hyundia tucson 2.0 petrol but after a few minutes it was gone but it sound like it was coming from the head of the engine must i worry about it?
Yes, it can also be from the timing chain hitting the oil squirter, not good
Thats piston slap, these are common on Hyundai's
@gicugigel3790 not really common on Hyundai
@@Motorcarnut from what i've seem, pretty common, both on diesels and gasoline engines. Their engines tend to develop piston slap or rod knock. My Hyundai engine had piston slap, replaced the engine and the new one also developed piston slap. I've seen theta 2 with piston slap and even V6.
The guy from 1st comment, says his engine knocks and gets quiet when warm, thats piston slap 100%. Thats the way a piston slap acts, at least before gets worse over time and wont get quiet anymore.
True about the piston slap getting quiet when warms up but no so many Hyundais came my way yet with this particular problem.
I get a tick that I assumed was lifter issue , it occurs a low revs and hi revs any idea why there is a sweet spot where the sound goes away ...is the con rod bearing likely?
That can be a collapsed lifter. Is there a misfire present?
@@Motorcarnut doesnt missfire
Could be piston slap, connecting rod won’t go away
@@Motorcarnut I am going to get it into my garage and check/set the OHC lifter gap ...what does a collapsed lifter look like?
@ziffification would have excessive valve lash between lifter and valve
is piston slap not slapping when doing engine brake? mine when i step the gas its sounds knocking like in the video, but when i do engine brakes its gone (sorry for my bad english)
It's less when braking but still there, yes.
@@Motorcarnut ahh i see, thanks for the answer
No problem
hi great video , piston slap is gradual or just suddenly starts one day ? thanks
Piston slap is gradual as it starts to wear.
Does a quiet slight knock mean you need a new engine?
On a Subaru probably not
Depend, if you have rod knock but you stop the engine soon enough you can just rebuild the internal and the engine will be good for a long time, sometime the block have no damage and can be save. It just cost a rebuild wich is cheaper than buying a brand new engine.
Sounds be like that, but everything works normal, right?
Most of the time, yes
Washing machine vs helicopter
I guess, lol
Does a rod knock mean engine replacement ?
Short answer, yes but also can be rebuilt
Hi. If it’s a rod knock. How long do I have before engine is defective?
Immediately
@@Motorcarnut the knock comes and go away. Sometimes I idle and I don’t hear it at all. At time at hear it. Also slight hesitation when starting.
Thanks for your reply.
You can’t play around with engine knock it will destroy engine without any more warning signs
Mine did that on my Corolla. I can’t drive my Corolla anymore. Lol.
@maegantucker973 nope
My motorcycle has only 2200 miles on it and there’s an engine knock. Not a bad knock, and it’s is hard to hear at times, but there is a knocking.
Considering the bike is new, could bad oil cause knocking ?
It could but it's usually from low oil or low oil pressure. If the motorcycle is under warranty I'd bring it in for service before any damage happened if not already.
@@Motorcarnut : it came out of service in this condition and they refuse to acknowledge the knocking.
Two days ago I brought the bike in, waited an hour and a half for the engine to cool down, the general manager and the service manager both came out to listen and the said it was normal and it was the valves. It does NOT sound like the valves to me. It’s a hard metal to metal sound.
The service manager says he doesn’t hear it. I say he doesn’t want to hear it.
Everything I say, they just deny.
I called Triumph in England and Patrick in the after sales department is as useless as tits on a bull.
I’m really stuck here with this dealership and triumph not willing to help.
I may have to use the news channel to solve this. They have a unit that solves problems for people.
@ginoasci2876 can you make a video on your channel and I can listen to it?
@@Motorcarnut : that’s a great ideas.
I have quite a few but I’ll upload one that is undeniable.
@@Motorcarnut : uploaded two short videos. If you listen you can definitely hear it.
Really appreciate the help.
I have a video on my page can you tell me if it’s a piston or rod knock
I just did. That definitely sounds like a rod knock. One thing you can do to rule out an accessory or pulley noise is to take off the serpentine belt and start it back up, if it sounds eacly the same its a rod knock and would have to be rebuilt or replaced.
I dont have a subaru anymore but i have an 02 accord im trying to flip, upon start it makes a knocking type sound but only on cold starts. After 10-30 secs it goes away and the car drive normally shifts smooth and makes no sound. Is it bc it’s basically oil starved on cold start and as oil circulates it goes away?
It very well can be. If you didn't already, try changing the oil and filter and using a oil additive like STP, should help.
@@Motorcarnut i did an oil change and the time it takes for the noise to go away is way shorter than before the oil change, im gonna try stp and see if it stops it completely
@Andy3x yes, it’s cheap and worth a shot.
I must have a bad ear on this stuff it sounds like my truck but my sound is constant and follows rpms i have a short clip on my channel
I’ll give a listen when I’m on my desktop.
@@Motorcarnut i'd appreciate that
Just happened to my car 10 days ago
Sorry to hear that, maybe it can be rebuilt or replaced?
@@Motorcarnut I must change the engine or I will sell the car
@alihasan-dg7vz Yes, but first get a second opinion from someone local
Hi is both cars cold start up
Yes
@@Motorcarnut hi is ther any way I can send videos direct to u for advise
Post on your channel and I will watch it
@Motorcarnut ok Thank's
@Zigggy87 no problem
Sounds like diesel clatter
Yes it does.
That’s garbage my 4.2l ford with 300k miles on it sounds quiet as a Prius compared to this thing. I’d be scared to drive that pos around the block both of them sound like the pistons are about to shatter from all the slack and vibrations. Really sounds more like a wrist pin knock instead of piston slap.
You never owned a Subaru.
Im definitely the second car 😢
??
What if the rod knock goes away?
You’re very lucky
@@Motorcarnut I used the wooden dowl rod method to listen to the inside of the motor. And it was clattering loud. The tensioner pulley started making a noise and the power steering went out the ps pulley started screeching and the knock went away at the exact same time. I changed the tensioner pulley and power steering pump (I used the original pulley) and the vehicle runs great. So I'm actually thinking it was the ps pump that went out causing the pulley to screech and knock.
Great diagnosis! That was probably it!
My car is doing this and just cut off ‘
Have it checked out asap hopefully you didn’t blow the engine.
@@Motorcarnut unfortunately I did 😭 have to get a new motor
Sorry to hear that
Makes me want to stay away from Subaru either way
That’s understandable, but they still make great vehicles. The design of these engines is what makes them more noisy than the competition. But the newer ones are more refined.
There's nothing wrong with a Subaru.
True
The newer F engines leak oil and have TCV failure.