Knocking Sound, help with diagnosis?

[iammike]

I've never owned one of the boxer engines before so I don't know anything about their normal ins and outs. Just bought a 1998 Legacy Bilstein Edition today, EJ20H or EJ20R TT (picture later, can you tell which one?), automatic. This is JDM by the way.

Ok, the car has a knocking coming from the engine area that I'm having trouble diagnosing. It wasn't immediately apparent when I first drove the car but I noticed it over time. Car makes good power, no hesitation, the knocking doesn't seem to get louder as the RPM's ramp up. When I'm sitting in the car, I can only notice the knocking at idle and it's more pronounced when in gear at a dead stop as the video will show. I have noticed no smoke, exhaust smells normal, no coolant in the oil. Got a fresh oil change to make sure it didn't have super old oil but no help.

I'm hoping this isn't something that will require me to do some kind of rebuild of the engine but I've got nothing to go on right now. If I'm lucky, maybe it could be an exhaust leak. Maybe it's injectors...but doesn't sound like it to me.

Thanks for any help you guys can provide.

Video of the noise:
http://www.youtube.com/watch?v=W74cuGPfJGw

Engine pic, is this EJ20H or EJ20R?
http://i265.photobucket.com/albums/ii21 ... 000645.jpg (http://i265.photobucket.com/albums/ii215/iammike08/Temp/P1000645.jpg)

[iammike]

Recorded a better video with light this time. This sound really concerns me!

http://www.youtube.com/watch?v=aMUc3TUwFWU

[Perkul8r]

That sounds pretty bad, sadly usually when i have heard a deeper thud like that its a main or rod bearing. You could drain the oil to see if there is any metal chunks or large shavings in it. I mean without pulling the oil pan that would be the easiest.

[iammike]

I'm really hoping against those types of things. Every video I listen to on YouTube either involves a much louder, much sharper knock (the kind that would prompt an immediate pull over and shut down on my part, or an irregular knock meaning it doesn't keep a rhythm. Mine stays in perfect timing with the exhaust note and doesn't get noticeably louder with RPM...or to say it doesn't sound as bad, definitely not worse, at 1500 RPM and by 2000 RPM and up, I can't even hear it anymore.

One thing is for sure, it's driving me nuts. lol

[Perkul8r]

That is true, it would vary with rpm if it were a rod knock. But on the video(maybe its just my shitty computer) it sounds just like y old as V8 did when it threw the middle four rods. lol. I used to have a car that had a slight knock at idle, but went away when you were driving it. I can remember what it was.

[iammike]

Well the speed of the knock varies with RPM but it doesn't seem that the volume does.

Maybe I'm gonna get real lucky here though. I had a lot of driving to do at lunch today, I noticed towards the end that I wasn't noticing the knock anymore. Upon closer listening, the knock is still there but much less noticeable.

Only thing I've done in the 2 days I've had the car is to do an oil change to 10w-30 Semi-synth and put in some fuel system cleaner.

Is it possible that there could have been enough crud on a valve seat that it was causing that kind of noise? That would explain why it was in rhythm with the exhaust. Maybe that cleaner broke something loose.

[Perkul8r]

its a possibility. The oil change might have even taken care of it. Now that i think of it, the knock kind sounds like my 04 leggy at start up. I have talked to a couple Subaru techs and they all tell me that its just piston slap. But dam when its cold it sounds like a diesel truck. But after driving it goes away. I know i need to change the oil. I cant remember what the previous owner put in it. So maybe it was just some sludge causing a slight lack of oil somewhere and changing the oil took care of it.

[iammike]

Maybe, it came back again last night after the car had to idle for awhile when I was parked. I'm supposed to drop it off at a shop today to see if they can tell what it is.

[iammike]

Soooo, shop visit resulted in my being told "it's not a knock, it could be a valve or something in the head on the left side". By left side, that would be the passenger side for a right hand drive vehicle.

Doesn't know exactly what it is because the engine has to be pulled to pull the head.

Figured I needed to be sure it wasn't something more simple before I start digging inside so I went out tonight to make sure all the plugs looked good and were not loose or something...the lack of a 12mm socket stopped that project cold.

I'm sure I would get some kind of check engine light if either of those were the case though.

Still don't have an answer on the oil pressure. Garage didn't check it (rolls eyes, I asked them to). I figured, hell, I'll just add a gauge in the car, well the cheapest gauge I found on the shelf was over $200. YIKES!

Was going to pull the 10mm bolts and check the one timing belt...can't reach the bottom one to put it back in if I were to take it out.

Uggg, this car is beating my arse at the moment and driving me nuts.

[Perkul8r]

I know how it goes man. I am currently turning my NA 1998 Legacy l into a turbo car. They are a B**ch to work on, but i look at it as a challenge. At least you got a factory turbo car. I would love to have one of those. lol

[iammike]

Well I pulled the timing belt cover from the passenger side bank today...everything in there looks perfect.

I'm pretty much down to oil pump or something internal. Gotta find someone around here that can check my oil pressure for me.

[Robbks]

OK.
1
hard to tell what engine it is from the pic.
does it have yellow or grey injectors?
yellow = 440cc = EJ20R
grey = 380cc = EJ20H

however, being an auto GTB would lead me to assume it's an EJ20H.
ONLY the manual GTB's got the EJ20R

My EJ20R has the same sound but not as bad, and only when very very cold.
it's piston slap from the forged pistons.

given yours is also EX JDM (How many KM's?), they don't like so service cars very well and it could well be piston slap from worn rings.
as the engine heats up and clearances tighten the slap gets less.
have it compression tested.

it could even be as simple as a stuffed water or oil-pump

[iammike]

I found out on the under-hood code that it's a EJ20H. Forgot to mention that.

As far as mileage, 108,000km's. Been pricing out a timing belt change and they said that with all new belts, new tensioners and new waterpump along with some new seals I'm looking at like $600. Wondering how much it would cost to replace the oil pump while they are in there.

Also, as I posted on another forum:

"I've been noticing lately that this sound is not constant either. Not in volume anyway. Sometimes I can't even hear it in the car...other times it's rather noticeable in the car.

Seems to be that if I let the car sit and idle for awhile, or go through a lot of stop/go, which is basically everywhere here in Japan, it gets louder. Sometimes I can come to a stop light and go from barely hearing it and it will slowly get louder while I sit at the light.

On the flip, it also makes the noise while the engine is dead cold like the first start of the morning.

This all makes me think oil starvation in one or both of the heads, what do you guys think?"

[Robbks]

it doesn't sound like the usual oil starvation noise
aswell as the Gen2's don;t have the HLA's which were prone to being noisy.

as a test, i'd throw some nice thick oil in it and see if it makes it better or worse

also if you're worried about blockages causing oil starvation, use some "Diesel Engine Oil" which has lots of detergents in it and is good for removing carbon build-ups in the engine.

get an oil pressure gauge on it and see if it has sufficient pressure

[iammike]

This problem confounds me. lol Well, I would think anything seriously wrong internally would generate a knocking despite engine temp or RPM. Am I wrong to assume that?

[Robbks]

the only issue i can really see is if it's a dying pump (water or oil) which leads to oil starvation or overheating and killing the engine completely.

meh, it's only an engine. good excuse to drop a 2.5 in it.. :D :D

[MiikeC]

I have the same problem, and am going to change spark plugs soon to try to start eliminating possibilities. Oh yeah, I have the same car with 60,000km.