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Discussion Starter #1
Went autoxing yesterday for this first time since May. I have been doing more road course stuff lately with it.

The autox was going well. Car was being two driven by another local driver who is very good. We got about 12 runs in and the car started to idle very roughly. Turned the car off and back on and we were greeted with a spy hunter cloud of smoke out the exhaust. (the left side of the exhaust flows much better than the right btw) This was followed by a missfire code on #2.

Great!! Sounds like all the classic signs. Get it back to the shop and pull the plugs. They all look very good. Do a compressor test with the results of 125-130 on 1,3 & 4.....all normal. We did #2 last.....35psi. Sounds like another cracked ringland.

We are pulling the motor today to take a look at the condition of the block and other bits. New pistons at least are going in...possibly a sleeved block.

Pics to come.

Tony
 

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Discussion Starter #2
Sorry for the late reply. Been taking the motor out. Everything is ready to go, just have to get the engine hoist on and remove it from the car. Been working slowly taking mental note of everything and inspecting as I go.

As far as the condition of the car. It had 633 miles with the stock tune. During that time the motor never went above 4500 and never went WOT. I could tell the tune was crappy from the start and didn't want to chance it. Car is a pre-stop sale engine. It was purchased in the middle of Feb and was one of the first in the mid west.

At 633 miles it received a stage 1 tune from P&L Motorsports. At 3500 or so it got a stage 2 tune. At 11000 or so it got a P&L Intake and another tune. Car has run flawlessly during this time. Problem ocurred at 17011.

The car has seen 4 or 5 track days and a few autox's. Most of the street driving has been pretty easy for gas mileage concerns.

I am fanatical about maintenance!!!! The oil was changed at 400 miles with regular dino oil. It was changed again at 3000 to synthetic. Since then it has been changed every 2500 - 3000 miles or before a track day. Oil was last changed 500 miles ago using Motul 300V 5W40. Before that the car has always had Castrol 5W40 starting at 3000. The engine did not burn any oil between changes....not a drop!!

By the fact that it is piston #2 that seems to have died, I really see this as being an issue with crappy pistons. If it were 3 or 4 I could see heat being an issue as everyone for years has talked about (not saying I completely agree with this or not).

As far as the plugs and O2 sensor goes, they all look perfect. They are all a light tan color and show no signs of detonation. I also have not felt any det while driving the car on the street or track. In no way do I feel this is a tune issue. Jorge is a great tuner and has always done well with the car.

I would never even consider taking it to the dealer to have them fix this. What would be the point of having them put in crappy cast pistons again? Plus I know I do better work than the techs that would be rebuilding it.

More to come as I start the tear down.

Tony
 

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Sorry to hear about this guys. It was a great performing car.

Were you using the Stage 2 Protune for autox? If so, that kind of puts holes in the theory that it's the tune that makes the engines pop.
 

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Thanks for the update Tony - that's pretty much the scenario I was afraid of. I only had the stock tune on my pre-stop sale car for ~200 miles, never went WOT, and changed the oil at 2000 miles to be safe. Now I'm thinking stage 2 will have to wait until I can pull the block and do the cams as well. :mad::mad: Awaiting news on whether the cylinder walls are ok.

Frank
 

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You know Tony, thinking about this, if the compression is THAT low, it's almost like there's something major like a hole burned into the piston. Or a dropped valve. Usually ring lands drop 30-40 PSI... Not RUN 30-40 PSI.

Regardless, if it IS a piston, I say just toss in some good forged units (with the mileage, you could probably get a way with it).

Interesting to see what you find when you tear it open.

-Jorge
 

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Discussion Starter #6
So - to go back on topic.

Motor is out of the car. Tony is continuing the breakdown. Jorge, I had thought of the cracked piston. We'll see once we get it out. Overall I'm just curious. Either way, I hope we didn't drop a valve, as that would be major suckage.


The car had FTD before retirement from the event.
 

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Discussion Starter #9
Hi,

Sorry to hear about your trouble. Can you post pics of the rings and pistons , please. We have seen a similar issue before but would like to see some different incident.
Oh believe me - we'll be throwing up pics of those in great detail. :)

We also need to figure out what pistons and rings to go with. And then it goes on to the question of the bearings....

And then we need to wonder if we should have the heads flowed and ported.....

We seem to go through a huge decision tree on all of this whenever we end up pulling one of the motors on our own cars...
 

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Discussion Starter #10
Sure is nice to have your own shop to be able to do these things!

Much luck to you guys!
Yes. Yes it is. :)

Sad part is we're suspension guys, but we've had more motors out of scoobies since we've moved to this new location than we've had suspensions out of scoobies. :(
 

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Sorry to hear about this guys.

What HP and TQ was your car making? And what did you use to tune it?

Looking forward to see the pistons. Hope the cyl. and the heads are still good.
 

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Discussion Starter #12
Sorry to hear about this guys.

What HP and TQ was your car making? And what did you use to tune it?

Looking forward to see the pistons. Hope the cyl. and the heads are still good.
i don't remember the exact numbers, but it was somewhere around 300 whp, and 360 wtq. it was a protune done by [email protected]&L

Update coming up next.
 

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Discussion Starter #13
Update - it was #2. both second and third ring lands were so cracked that they just fell out of the piston. Fortunately, the cylinder looks ok, but I have not had a chance to really clean it and look at it under a bright light.

Another thing that I noticed was the thrust wear on the skirts. It's higher than I would like to see on a 17K mile car. I'm going to mic those out along with the cylinders and see if I can figure something out. From the look of it I personally think they are rocking a bit more than they should (but that's just my opinion).

As for the dead piston - I know we have a couple of folks bouncing around who do metal failure analysis for a living. If either of those guys run across this then please contact me. I would like to hire you to look at the start and cause of this failure. I have a theory, but I'm no metallurgist.

-Clint

Now, on to the pics:















 

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How do the piston tops look at 17,XXX miles?

bytor's pistons were caked with carbon at only 1,987 miles. It'd be interesting to see what a 17,XXX mile piston looks like.

Gary
 

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Update - it was #2. both second and third ring lands were so cracked that they just fell out of the piston. Fortunately, the cylinder looks ok, but I have not had a chance to really clean it and look at it under a bright light.

Another thing that I noticed was the thrust wear on the skirts. It's higher than I would like to see on a 17K mile car. I'm going to mic those out along with the cylinders and see if I can figure something out. From the look of it I personally think they are rocking a bit more than they should (but that's just my opinion).

As for the dead piston - I know we have a couple of folks bouncing around who do metal failure analysis for a living. If either of those guys run across this then please contact me. I would like to hire you to look at the start and cause of this failure. I have a theory, but I'm no metallurgist.

-Clint

Now, on to the pics:


Quick question, when the rings were still on, could you move them around significantly..? Amazing how the middle land broke. Second time I have seen pictures like that from these engines.

I think I know what your micing :) Are you thinking the second land wasn't smaller than the top land..? :confused:

Thanks for the photos!




-Garrett
 

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Discussion Starter #16
yikes!

it's moments like this that make me wonder why subaru still isn't using stronger pistons in these engines.

back on topic though. do you think that it was detonating?


J.
I don't think it was a det problem. plugs look fine, and piston surface looks fine. I think it's a crappy casting.

Sadly, Subaru used to do all forged internals. I don't know why they stopped.
 

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Clint and fellow TIC gang,

Sorry to hear this. This really does amaze me...I'm sure everyone is as shocked as I am. Considering the performance level of this vehicle, I agree with everyone else when they say Subaru should have put something stronger in these engines.

When did Subaru stop putting forged internals in?

Kind Regards,
Ryan
 

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Discussion Starter #19
Quick question, when the rings were still on, could you move them around significantly..? Amazing how that top land broke.

I'm wondering if the expansion of the rings isn't the same as the piston.

:confused:
Thanks for the photos!




-Garrett
The rings looked just fine, and end gap looked ok so I don't think that was it.
 

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cost, plain and simple :(

(and yeah, it would probably only cost them a few dollars more per car to put in forged pistons :( )
honestly, I'm starting to think the argument bytor and others should make with subaru is that all these broken pistons need to be replaced with forged ones. This would make getting the warranty service done worth it, but I figure subaru has already figured that out.

Frank
 
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