Bartek

Well, hello everybody. I am quite new to scoobys world. Still being a big saab's fan. Location: Poland. Need some info since my knowledge of subaru is close to zero but I'm a fast learner and I like to mess under the hood sometimes so now to the point . Subaru's '97, 2.0 N/A, over 200.000km which means more than 120.000 miles I guess. Correct me if I'm wrong - it's EJ20 engine. 1 year old LPG instalation - quite modern, Italian. What's wrong? Noises. Let's call it metallic tapping, louder when cold, quieter when warm, but it is still there. I know it is hard to describe and diagnose without hearing engine but I think you could point me some directions I can how the things are.
What could be involved? After my carefull reading of others' posts I can see some options - some are good, some very bad.

1. Quite good - TB tensioner. Cons - I can't hear noise is going from front of the engine. Noise doesn't go away, sometimes it could be heard near left wheel arch, sometimes both. Call me a newbie but I don't know how to check it and if THAT specific noise spreads through whole engine bay that could be hard to locate. TB wasn't changed through last 100.000 km but I would feel more comfortable if I know that this is NOT TB tensioner. If I change it and it will be more serious, replacing TB set would be useless (e.g. engine swap).

2. Rod bearing - tapping becomes faster when rpms go up. Cons - are bearings audible when idling? Oil looks clear but I suspect there is more than it should be - about 1,5 litre more. Also - oil light acts well - after shutting off engine and turning ignition on it appears about 1-1.5 seconds later, so it could mean bearings hold oil pressure.

3. Piston slap - after hearing mp3 with 'proper' piston slap I guess it's not my case - I have just tapping - no 'roooar' when decelerating. But - can I properly check it unplugging HT leads from coil?

4. Burnt piston - I hate to say it but it could be the most probable problem. Still know nothing about noise it could generate.

As I said: I need a help. I know it's like reading from stars but perhaps some answers could give me more clues and I'll be able to exclude some failures. Thanks.

TonyBurns

iTrader: (3)

Silly question but are you running a 5w30 rated oil?

Tony

Bartek

Not so stupid . No. Car is quite fresh and I can't get any info from previous user. I don't even know what grade of oil is used. You think it's not too thin for a car with 120.000 miles on the clock? Why oil could have something to do with noises?

st3v3

Usually oil would be thicker when its cold, as the car warms up the oil warms up aswell so the oil would get a bit thinner.

Can you make a recording and post it up on a website for us to listern to?

Bartek

Of course I can . I'm happy anybody wants to help me with that.

Bartek

Well, I've got two files - recorded by my dizzy mobile, but I hope in this one tapping/clicking/whatever should be audible even with this poor quality. Please listen and judge what could it be.

http://uploadhut.com/view.php/275041.wav (ca 500kb)

dan83590

To me the pitch sounds too deep to be anything from either of the Heads. It sounds to me like it may be a worn Con-rod, Big-end. A worn Big-end would be audible at idle, espeicially when the engine is cold.

st3v3

Hi Bartek, finally got wav. to work as dan /\ says it sounds a bit like a big end, does it get alot lot worse as you rev the engine??

Bartek

Thanks guys - actually I noticed something's wrong with this upload site. I guess it's getting a little worse in 1200-1500 rpms range, but then it gets quieter. Con-rod you say? If it is so, what should I do? New con rod, bearings, anything more could be trashed? And what about oil pressure light? Shouldn't it be lit?

If you've got another spare minute there's another audio file with a little revving - I hope this time should be no problems with it. Still poor quality

YourFileHost.com - Free hosting for ALL your files

Heple

If thats a big end bearing it SERIOUSLY knackered that is a hell of a lot of knocking going on there!

Craig

Bartek

It is quite loud but not so one couldn't stand it. You hardly hear it from inside car, but when I stood about 5-6 meters from the car I could hear only silent tapping from under the hood - engine wasn't audible. Any tests I can do about con rod? Compression?

And one more thing - how about simple swap? Can any of subaru's engine be painlessly put into '97 forester N/A?

st3v3

back up for our foreign friend......and an expert opinion on this would help him alot.

dan83590

Expert opinion anyone??

Bartek

Anyone? I assume there's a distance between bearings and conrod so it is possible piston's crown might hit valves. Still I am not sure if this is situation I've got. Is there a way to check it? And what about crankshaft?

mattjbvfr

I just ran your wav file through a spectrum analyser.
The knocks are occurring at at about 7Hz (or 420 knocks per minute).
The rate of knocks is therefore at half engine speed assuming your car is idling at about 800 or 900 rpm. So this suggests that the noise is either coming from the valve gear which operates at half engine speed or if it's coming from the bottom end then it is every other crank rotation - possibly the power stroke of a particular cylinder. You could try disconnecting each spark plug lead in turn, if the noise remains then it suggests the problem is valve gear. In my experience bottom end noises usually increase dramatically with engine revs due to the increased forces necessary to accelerate/decelerate the pistons during each stroke. Hope this helps.

Matt

Bartek

I thought my knowledge of English is enough to understand all technical talk, but....errrr....it's not. Matt, please enlighten me a little. Math is simple - one whole turn of crankshaft - two knocks, right? Assuming it's quite regular it could be one particular cylinder rod? I tried to disconnect 2 (one after another) of HT leads at the coil, but...I chickened...sparks were going through one socket to another causing quite loud knocking itselves. I could here knocking is still there - they were 2 RH cylinders. I'll try to be harder and disconnect 2 another. What's power stroke? You mean knock occur when rod is up and down? Sorry for these question...they might sound silly a little.

mattjbvfr

No, it's 2 whole revolutions of the crankshaft equal 1 knock.
(2 whole revolutions of the crankshaft equal 1 revolution of the camshafts).
Therefore it is likely the noise is coming from the camshafts/valves.

If the knock is coming from the con rod it is not occurring on every crankshaft revolution.

Matt

Bartek

OK. You're right. Don't know should I be happy or not? Stuck/bent valve? Or something else? Everything not concerning my big end is some kind of joy. Do you have any suspect, Matt?