2005 Subaru Legacy 2.5 NA knock has me freaking the F out...

Sorry in advance for the piss poor grammar and likely spelling and punctuation errors. Kind of typing in a rush and a bit worried.

 

I have a 2005 Subaru Legacy 2.5 NA (non-turbo).

 

Today as I was getting off of the interstate I pulled up next to a car and heard a knocking sound coming from my car (deflected off of their car).

I pulled over and popped the hood and noticed it's coming from the engine compartment.

 

Engine oil was recently changed (full synth high mileage oil about 2300 miles ago) but a little low (not terribly low). Coolant was a little low, but again not at a problematic level.

 

The knock sounds very much like a rod knock (but I really hope it's not...knock on rod wood) but it's coming from front center of the engine as far as I can tell (don't have a mechanics stethoscope but used a tubular vacuum accessory to help localize the sound). It sounds like it's coming from just below and slightly behind the alternator. Could it be a loose pully/bracket/belt issue?

 

 

 

I just purchased a new house and can't really afford to buy a new car at the moment (well...let's just say I'd rather not..though I must admit the Crosstrek has caught my eye).

 

 

 

Any ideas?

Thanks in advance!

I would say to try and get an audio/video clip if you can. You can email it to me and I can host it up for people to hear/see.

I can try. I've actually never uploaded a vid from this phone so I can't guarantee audio/vid quality.

 

Email address?

youtube link

http://youtu.be/6mBb4qtUlmI

 

video only link

http://home.comcast.net/~apexigsx/subaru/JayInVA/VIDEO0007.mp4

Appreciate the help!

My 08 lgt is making the same noise and it sound it it's coming from the same spot. But on my car the noise only gets loud when there a load on the motor and will go away after 10 min. Someone told me it's probably a valve or a lifter needs adjusted

Go by mechanical breakdown insurance from your insurance company and then just keep driving the car.

 

In all likelihood it's not a simple fix and will involve pulling the motor.

The knocking sound seems to have decreased significantly since yesterday.

 

A few minutes ago when I started there were loud knocks for the first 2 or 3 seconds (long enough for the engine to fully turnover) and then no knocks at idle. The knocks pick up a little as I drive.

 

I also noticed that the knocks seem to increase in loudness/intensity as the RPMs fall (by letting off of the gas) vs during acceleration. I can't tell if it's perhaps just that they're masked by exhaust and engine noise.

Go by mechanical breakdown insurance from your insurance company and then just keep driving the car.

 

In all likelihood it's not a simple fix and will involve pulling the motor.

 

At 196k miles, I believe I may be beyond the limits of breakdown insurance, unfortunately.

That's harsh! Try adding a Lucas oil additive to thicken the oil see if that helps. If it does nothing may be a rod.

 

My timing belt tensioner makes a noise sounds kinda like that but not as loud get a stethoscope and see if you can't pinpoint the exact location.

 

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That sounds like valve train noise not knocking from a rod. If it were a bad rod/bearing, it would get louder with higher RPMs.

Have you always used synthetic? If not, that may be the issue. Synthetic 5W30 or 10W30 seems to be a little thinner than the conventional stuff and your engine may sound noisier when you use it. Try putting some oil treatment as previously suggested to thicken the oil a bit.

 

On a push rod engine if you hear loud valvetrain noise immediately after startup, it's usually due to a gummed up lifter that doesn't fill up with oil fast enough.

On overhead cam engines they call them cam followers or tappets, but the same issue can happen.

That sounds like valve train noise not knocking from a rod. If it were a bad rod/bearing, it would get louder with higher RPMs.

Have you always used synthetic? If not, that may be the issue. Synthetic 5W30 or 10W30 seems to be a little thinner than the conventional stuff and your engine may sound noisier when you use it. Try putting some oil treatment as previously suggested to thicken the oil a bit.

 

On a push rod engine if you hear loud valvetrain noise immediately after startup, it's usually due to a gummed up lifter that doesn't fill up with oil fast enough.

On overhead cam engines they call them cam followers or tappets, but the same issue can happen.

 

I would agree with you on the sticky lifters.

 

Your right about rod bearing noise.

 

At 2300 miles you might was well throw some seafoam in there clean it up a bit and after a week of driving change the oil to something a little thicker. I run mobil 1 full synthetic. Found that to work the best for my N/A 2.5 with 210,000 on the odo.

 

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I'm assuming you are referring to my comment on the synthetic likely causing engine to be noisier.

My father had a Ford truck with inline 6 engine. Most durable engine he ever had in any vehicle he owned. He put about 150,000mi on it before he sold it. It didn't seem to burn a drop of oil between changes...

 

Anyway.. after 50,000 or so miles he decided to give synthetic a try. He used Mobil 1, 10W30. Immediately you could hear a little clacking sound that was still present after it warmed up. He ran it for a week but was so concerned by the sound that he decided to drop the oil pan to see if he noticed anything wrong with the rod bearings. They were fine, he only noticed slight back and forth play of the rod sliding a tiny bit on the journal... So he buttoned it back up, refilled it with conventional 10W30...

And guess what, no more clacking... I witnessed all this..

Since then, he hasn't used synthetic. I use the stuff but only in 10W40 form.

Another piece of information, for your consideration (see what I did there?!) :

 

The knocking/ticking sound is very rhythmic (1,2,3,4,1,2,3,4,1,2,3,4) with every 1st beat hitting at .7 seconds. That gives an approximate 5.714 bps or 342.85 bpm. Because this measurement isn't exact (stop watch only measures to tenths of a second so the .7 seconds could be anywhere from .649 to .749), we'll estimate that the knock occurs at a rate of approximate 1/2 of RPM.

 

Is this significant? If this were piston or rod related, wouldn't the knock occur at RPM frequency? Correct me if I'm wrong (and it's quite possible that I am...I'm no mechanic).

 

Also, if this were rod and/or piston related, how loud would the knock be? I'm looking at other youtube videos of rod knocks and they appear to be very loud. In my case, on the other hand, I can't really hear the knock in the car unless I'm idling (particularly in my car port or next to other structures that deflect/reflect the sound back to me). Just driving around, I can't really hear it within the cabin.

 

Obviously, I know trying to diagnose this sound online is futile (at best....perhaps dangerous at worst), but this is what happens when your mechanic can't see you for a few days so you spend every waking hour thinking about what could be wrong with your car!

Low oil pressure light ever come on?

 

You could change your oil and send the old to Blackstone Labs for them to analyze. My girlfriend's 08 just cracked a valve guide, chewed through the oil, and threw a bearing a few months ago. Had to put a new shortblock in along with a new head (got cracked). Hopefully you have better luck!

Low oil pressure light ever come on?

 

You could change your oil and send the old to Blackstone Labs for them to analyze. My girlfriend's 08 just cracked a valve guide, chewed through the oil, and threw a bearing a few months ago. Had to put a new shortblock in along with a new head (got cracked). Hopefully you have better luck!

 

The oil pressure light has come on only once to my knowledge and then just briefly.

 

I was pulling into a toll plaza and some guy cut me off so I had to slam on my brakes. The light flickered on and then immediately off. Never had the light come on before or after that. Oil level was fine when I checked later that day.

Have you ruled out a frayed cam belt flapping against something inside?

Well no oil pressure light is a good sign.

 

As Donny said check the belts and pulleys. My Mom's Protege sounded like it was knocking and it ended up being something with the timing belt/tensioner (can't quite remember).

 

My VR4 also has loud "lifter tick", especially when the engine is cold and the oil is thick.

 

Not sure how to diagnose it online but good luck!

So...just heard back from The Subie Guy.

She is dead.

 

RIP

What was it?

 

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Rod bearing.

 

So now I decide if I should rebuild, replace or new car.