Subaru Head Gaskets...today's carnage

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Sorry I didn't add the explanation, but here it is.  Bought a 99 with a bad engine as there was a spare engine in the garage to donate.  Had to see what was wrong, PO just said it died on the highway.  Head gasket actually looked pretty good, especially compared to the carnage in the cylinder.  Three of four had the chunks blown into the coolant passage.  

Not sure what happened, but the gasket is pretty much intact.  Heads look great but the rest of the motor is scrap metal.

What exactly are we looking at?

In reply to Knurled. :

Bottom of a cylinder.  Looks the same for 3 of 4

Here is a better shot

Boosted?

Technically that's the top    Neat, never saw an open deck block torch the block like that.

IS that a wet liner that's melted away into the coolant passage?  What the hell are Scoobie liners made of, cheese?  How did a steel liner melt and not the head?  

In reply to Adrian_Thompson :

Looks like the steel liner is still intact and the lip of the aluminum block blew out into the coolant passage. I still wonder what brought that about.

Head gasket failure and a hot spot formed on the outside of the liner. It looks near the exhaust valves so hot exhaust gas escaping past the gasket.

JohnInKansas said:

In reply to Adrian_Thompson :

Looks like the steel liner is still intact and the lip of the aluminum block blew out into the coolant passage. I still wonder what brought that about.

This ... we see most aluminum block designs these days have aluminum extend up past the top edge of the cast iron liner, as machining a cohesive sealing surface in all aluminum for the head gaskets is much easier to control vs. machining a composite aluminum / cast iron surface if the liner projected all the way up.  I always wondered if there would be a performance / durability downside to that design decision ... maybe this is it.

In reply to einy :

In reply to JohnInKansas :

Ah, thanks guys.  Does anyone have a pic of a virgin same series block that we can see if this is the case?

Stock 2.5 in a 99 outback with under 100K miles.  Engine was rebuilt at some time, head gaskets are MLS and the inside of the engine is pretty clean.  I agree that the head gasket failed and a hot gas leak ate the block but here is the wierd part: the head gasket looks great.  It is perfectly flat, no warp or missing bit.

Here is a pic of the block with the gasket still on it.

I wonder if someone replaced the head gaskets and scratched the deck by hamfistedly scraping, instead of using carb cleaner and a rag like you're supposed to.

In reply to Knurled. :

I like that idea.  I know when I was a a dumb kid I used to clean the deck of my Hillman Imp blocks with chisle.  Imp block pic for comparison (not, this is the 'big bore' 998cc not the normal 875cc!!!)

Knurled. said:

I wonder if someone replaced the head gaskets and scratched the deck by hamfistedly scraping, instead of using carb cleaner and a rag like you're supposed to.

I am going with you on this.  The valve cover gaskets looked like new, yet there was a bunch of leakage because they didn't goop the corners like the pros do.  The head bolts looked new also, I think someone did head gaskets and didn't know how to do it right.  The theory was also mentioned by a buddy that works for subaru.  

The replacement engine is running fine, but thought we messed up something doing gaskets on this one.  Turned out there was so much coolant and oil in the exhaust pipes it took 20 minutes to boil it all out.  

I had another thought...  Normally when you lose a spark plug ground strap, if it doesn't blow out the exhaust, it stays on top of the piston and melts its way through after you replace the spark plug.

On a boxer engine, it might melt its way through the block if the top is bare aluminum.

Hmm.

In reply to Knurled. :

Not on 3 of 4 cylinders though.

Oh my.

I have seen that on marine outboards before. Usually caused by crevice corrosion where the head and block meet. The corrosion eats the aluminum back far enough that the gasket fails. From there it's a short run to burning it out the rest of the way. 

You'd really have to chunk the deck surface with a razor blade to cause that kind of failure, especially with composite head gaskets.  With MLS gaskets sure, the surfaces need to be more flat  and clean but composite is more forgiving.

In reply to engiekev :

Those are MLS.

Knurled. said:

In reply to engiekev :

Those are MLS.

My mistake, I thought the older subaru gaskets were composite, with the popular fix being the STi MLS gasket. Porschenut's pic looks like a composite gasket.

Are all the newer subarus MLS?

In reply to engiekev :

AFAIK, all EJ engines are MLS.

another thought, they missed a part when they cleaned up the block, leaving a small high spot on the deck that allowed exhaust gases to slowly leak past?