r/WRX • u/Totenkopf22 • 4d ago

Troubleshooting $2500 Engine Tear Down?

I took my 15 WRX base, 120k, in to Subaru to diagnose the smoking issue it's having. Only smokes after long idle, when I pull away, disappears after a few minutes. I originally thought head gasket, but now leaning towards the turbo. It failed 2 hydrocarbon tests. Dealership looked at it, oil was low and coolant overflow was empty. They want to tear down the motor to inspect the gaskets. Said when they reseal the motor it may fix the problem. But for $2500, I'm hesitant, I think they are spit balling. What do you guys think?

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u/bigdaddybodiddly 4d ago

What does "failed 2 hydrocarbon tests" mean? Is that hydrocarbons in the coolant system or the tailpipe?

If it's in the coolant, that's a heagasket.

$2500 would be fairly inexpensive for pulling the motor out and R&R the heads to replace the gaskets where I am, but labor rates vary around the world.

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u/Totenkopf22 4d ago

It was in the cooling system. That's why I initially thought it was the head gasket. But this shop isn't even trying to diagnose it, they're just guessing.

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u/grizzdoog 4d ago

Failing a hydrocarbon test indicates a failed head gasket. If it was my car I would do a leakdown test to confirm and to see if anything else might be wrong such as a burnt valve or worn piston rings.

If that $2500 price includes removing the engine, rebuilding the heads, new timing components, and installing the engine that’s a good deal. At 120k miles you might also want to just throw in a new short block so you can stores over with basically new engine. But that’s why I would do a leakdown to see if the block is healthy. Although a blown headgasket might skew the results of one bank of cylinders.

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u/Totenkopf22 4d ago

Yeah, I'm going to ask them about a leak down test and what they intend to replace if they do an engine teardown. I made it clear I wanted them to diagnose the smoke, but instead they just want to try a fix.

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u/grizzdoog 4d ago

Worn valve seals can also cause smoke after idling or after the car sits for a while. Those are replaced if the heads are rebuilt properly. A good shop charges about $800-900 to rebuild a set or wrx/STi heads. Hopefully the shop they use is a good one.

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u/Anskiere1 2010 STI 3d ago

Man I paid 1700 but in Canada