Engine problem - expert advice appreciated

[Nobody]

Haiya,
knocking sound of my engine was finally recognized by local subaru mechanic - it seems there are bad crankcase bearings or even crank itself. It is mainly on 6th valve, when disconected, sound is not so sharp. Car has 192k KM on it, engine is in perfect shape except knocking...
Is there somebody who changed crank shaft and crank shaft bearings? I need to set up some preliminary budget for desicion repair it or not. Also some hint of doing such a work is very appreciated. Local mechanic is quite familiar doing such a job on Legacys but no experience with SVX engine. I uderestand that engine has to be taken off - so many thing can go wrong. Thanx pals for any information.
Peter

[oab_au]

Hi Peter, I read your description of the noise on the European board. You say it is only there when it is running slow, at idle speed. Stops when the speed is faster.? You say that it stops when no. 6 plug is pulled,is this right?

Is the noise there when accelerating, or when cruising at a steady speed.?

I would be supprised to find that a crank bearing has gone bad.

Tell us a bit more, about it, did it start suddenly or has it slowly got louder. Is it there when enging is cold or hot?

Harvey.

[SVXer95]

Originally posted by Nobody
It is mainly on 6th valve, when disconected, sound is not so sharp.

Even when a plug or injector? (how did you disconnect?) is disconnected, the crank is still moving and would still make the sound. I too would be very surprised if it was the crank or a main bearing.

[TomsSVX]

sounds more like a personal problem.

is the sound a knock or a tick. a knock will seem deep rooted in the engine while a tick is more like tapping a screw driver on a cement floor. it sounds like you might have a funky injector or maybe a falty spark plug. make sure it's not something stupid before you tear apart your engine. Also, what grade fuel are you using?? you could be runnign too low of an octane and causing whats known as a ping. well hope to hear back and best of luck.

[UberRoo]

The movement and forces upon the piston and rod is very different during the power stroke. The forces are much more extreme. In fact, I think Subaru has offset the wrist pin slightly to reduce the stress and wear on the piston and cylinder primarily during the power stroke. I believe it is offset ~2mm towards the trailing side of the crank's stroke after TDC. Gosh... I sure wish I could remember where I read that. ...at least I think it was Subaru who did that - on the SVX no less.

Anyway, I saw the same symptoms on a small-block Chevrolet. Opened it up. Bad main bearing. I'm more familiar with piston slap, as I've seen it on motorcycle engines before. Same symptoms again. Rod knock, also the same. Sometimes a leakdown/compression test can expose piston wear which would indicate piston slap. That test will also give you an idea of just how "old and tired" your engine is, and how worthwhile a rebuild might be to you.

I would definitely try the spark plug test myself before getting excited about opening up the engine. On conventional engines with main bearing caps, it's common to simply remove the cap, slide out the old bearing, and slip in a new one. This only requires removing the oil pan and the caps for whichever bearings need replacing. With the oil pan off, it's also possible to check for piston/cylinder slap or clearance, as well as wrist pin knock.

For those of use familiar with the opposed engine design, there's a problem. You have to split the block to slip in a new bearing. I would think that a very clever mechanic might be able to change a main bearing by cracking the block only slightly and reaching in. Then again, that might also be quite difficult. Unfortunately, you still can't avoid pulling the engine, and once you've got the engine out, pulling the wrist pins and opening up the block just isn't that big of a deal.

Again, try the spark plug test yourself, just to be sure. If your test is consistant with the mechanic's test, I think he's probably right. It's one of four bearing surfaces. In order of what I think is most likely:
1.) Rod bearing
2.) Wrist pin
3.) Piston slap
4.) Main bearing

I hope the test comes out negative. Good luck.

[Nobody]

Wow, so many posts I have not expected :-).
I consulted this problem with my friend who specialize on engine repairs/repass but especially European cars like Audi, Mercedes or BMW. He has no experiance with boxer engines. He was not completly sure about the sound but probably agree with subaru mechanic.
This sound is really knock - it comes from engine deep and sounds very sharp, let´s say metal to metal (I thought first it is someting wrong with water or oil pump when the sound was no to sharp, it means it is getting more and more loud and sharp...)
What is strange to me it can be heard/recognized only on warm up engine and only at idle revs. When climate engaged or I rev a little it disapper (in engine sound? :-)) I use only 95 octane fuel.
Thanx guys I will do plugs check (and let you know). Do you think that crank shaft would be bad too? It is most expensive part...
Thanx, Peter

[NomadTW]

that octane you mention is it the traditional octane as we measure it in the usa, (RON+MON)/2
or is it just the ron value? i notice your in europe...

is that the best gas you can get?

[Nobody]

Yes, it is gas used for majority of cars here. We have Natural (means unleaded)92, 95, 98 (recommended for cars with turbos-WRX,STi, etc.), 99+ and some companies offer also 100+. I use only 95 from OMW or Shell. As for me it is not question of fuel. Engine works really fine (smooter than my Impreza), iddle revs are stable, runs perfect (except this ... noise). I can record this sound via my cell phone and post the .wav file here so maybe it will be more clear what is behind. Really appreciate all your help.
Peter

[Nobody]

So back again, plugs are ok, so being pessimist a lot of work and money in near future. Mechanic told me that there is possibility that crank is OK or will need to grind it little bit. Bearings are as for him 99% bad and have to be replaced (it is whole set, does not matter which is bad). I captured sound sample by my cell phone, but it seems that it is clear. Next question is what to be aware or to do else when engine is taken of and apart. Thanx for advices.
Peter

[TomsSVX]

i let this play for like 20 minutes and listened carefully. Yes, it involves a bottom end knock. Whether it is a rod or crank bearing i am unsure. I would say you will need a bearing kit for a rotating assembly. Thats crank bearings and all rod bearings and piston pins. this will not be a short project nor a fun one but good luck. Before you take my advice though, wait for a little more feadback to be completely sure.

[Nobody]

Yes, it is the same result we find out with local dealer. I would be very lucky if crank shaft will be ok and will not need to replace. They will remove cover to check it out so cross fingers. I have checked prices here and in states. It is unbeliveable, in states are prices on 50% on Europe prices. Wow! I have checked www.subaruparts.com (they do no except non US credit cards so I need to pay in advance:-() Did somebody does business with them?
Definitely, I will visit my and my wife´s famillies in California on September so my only souvenirs will be sets of bearings and other needed stuff :-(
Peter