Well referring to the EA82... obvious cylinder compression bypass.. you can *hear* the air escaping... it feels as though it's escaping through a cylinder head bolt hole (see pic) and somewhere else... is this a diagnostic bypass or something? Fwiw the car is also now putting out oil smoke through the exhaust... this random compression bypass is new to me... anyone? Bueller?

 

Thanks

 

Here's the pics:

the noticeable compression leak is from the bottom bolt hole; this is LHD pass side

There should be no exposed bolt holes on the cylinder head that penetrate into the engine block, much less the cylinder. Perhaps you could highlight which hole you are referring to in the picture?

 

On second thought, perhaps you are referring to the intake manifold, where it meets the head?

 

I would ask if it is a turbo engine, but I don't see any sort of turbo stuff and that is the side it would be on if you had one (iirc).

You will have to be more specific about where you are feeling air escape. Are you sure it's not an exhaust leak?

 

GD

It would be nice to know what year your car is or if it is FI or carb. With FI, it is possible a bad intake manifold gasket would cause that noise, but not an oily type smoke. If you are talking about blowby, where oil is passing by your piston rings into the combustion chamber, then you are probably due for a new engine. I personally don't believe these things are worth more than doing a head gasket job on.

 

However, I really don't understand what you are saying and how you are diagnosing your issue. If there was air escaping from a head bolt, your engine would more than likely be up ************ creek and coolant and oil would be everywhere. Have you checked your spark plugs? air might escape and cause some misfire issues if they are not tight enough.

 

Otherwise, your picture shows about normal Subaru oil leakage after 20 years.

spark plug may not be fully seated or could be stripped, causing an "escaping of compression" sound.

 

not going to be a bolt hole.

Apologies, it's a 94 non Turbo with SPFI. I'm on a phone so I can't highlight, but it's the lower hole directly to the left of the spark plug wire. I removed and reseated the spark plug and I'm certain it's not coming from there, as well as the exhaust Mani and intake. With the engine still relatively cool I placed my finger over said hole and the sound got noticeably quieter, although not completely. The compression coming through this hole is puzzling to say the least and is leading me to suspect a cracked head. I was just curious if this hold had any diagnostic relevance as it is apparent that there is something going on with it.

Also to be a bit more clear, it's the hole that the flashlight is focused on

there's supposed to be a bolt in that hole....how long has it been running/driving without that bolt in place?

 

how long were you previously driving this car without issues?

 

what lead you to finally start tracking this down...symptoms, etc?

That hole is not used for anything. both heads are the same casting, and this hole would be for the alternator mount on the other side.

 

if you can see into the hole, it is open with the drain hole on the back of the head, to drain off anything that pools up around the spark plug.

 

are you encountering this noise with the engine running, or when cranking it by hand?

It sounds like either you are feeling air that is being directed through that hole from around the spark plug or from around the EGR pipe or the passage the EGR pipe threads into.

 

Sometimes there are casting flaws that can lead to leakage even years after the car was made. It could be that some of the post-casting machine work punched into the exhaust port....

 

What symptoms are you haveing that would cause you concern other than this apparent leak?

 

GD

What Miles Fox said. That hole should bottom out with a dead end, or open to the air (to drain) but should not be open to the cylinder or valves at all.

 

If it is I'm going to recommend a new head .

soapy water squirted all over the area makes for a great leak finder... no good with vacuum leaks though.

 

I am leaning towards the tube connection behind heat shield next to hole... soap it down......

I will try the soapy water technique. What started this concern was an obvious and sudden change in engine sound; definitely compression leaking to atmosphere. It was after this that I noticed the oil smoke from the exhaust. Car was driven a MAX of 5 miles like this; just enough to get off freeway, diagnose, then drive home. Car has RELATIVELY low miles (114k) and very recent timing belts replacement. The opposing bank belt broke. I'm genuinely hoping it's something simple that won't require head removal, but it seems as though it's inevitable. I will report back with today's findings

double check to see if the exhaust gaskets are leaking. A blown out gasket will sound like a misfire, and can sometimes be mistaken for a knocking sound.

 

you may as well get new exhaust gaskets and studs and replace them for maintenance sake. You will thank yourself for doing this the next time you need to yank the engine or service the exhaust pipes.

 

new studs are crucial for keeping torque on the exhaust gaskets, and to not rip out the threads in the head.

 

also, there is an exhaust mount at the back of the trans. If it is not connected, the weight of the y-pipe will start to rip out the studs and compromise the gaskets.

Will do this, thanks. Also, just double checked my findings.. there is compressed air definitely coming out of one of those two bolt holes next to the EGR(?) pipe and not from the pipe itself. This is confuzzling; the soapy water trick only confirmed this and failed to yield any other obvious external leaks. Let me get back under and check exhaust for leaks again, just in case.

OK it's no external leak; it's coming from the head. Head is getting pulled off and inspected

I was going to say slap some JB Weld or a bolt in there if you MUST drive, but that would only be delaying the inevitable (and probably make things much, much worse). Money says you're going to have to replace the head, sorry

Yeah I was afraid of that... here's hoping!

PHEW! Turns out it was a blown head gasket. Very odd and concerning symptoms!