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2005 Subaru Forester - Ocassional Smoke from Engine

I have taken this car to two mechanics (including the local dealer) and no one can figure what is wrong. After driving from more than 5 mins I will ocassionally see smoke coming from the turbo vent in the hood. My latest theory is that condensation or rain water is building up under the hood and splashing on a hot part of the engine/exhaust. Both mechanics said the engine looks clean underneath and my oil light has never come on. I was a bit low on coolant after a hot summer but have topped it off and it is not leaking. Please help!

Smoke or steam? There’s a big difference.

Is the car moving or stationary when this happens?

How much coolant did you have to add to the radiator?

I could be steam but it has a bad smell every time (comes through AC vents and stinks up the car). It seems to go away after a few minutes (water evaporating?). Car is moving whn it happens. Added about 1/2 to 1 cup of coolant. Mechanic said he pressure tested coolants system and it was fine. Coolant level has not changed since I added about 1 month ago.

If it smells like stale curry it’s coolant. Pure steam would have no smell. I suspect you have a small coolant leak somewhere. Such a small leak would not show up on the engine.

The cooling system should be pressure tested first to identify the potential leak. I had a simlar situation with a Caprice, which had the dealer baffled, but a long distance call to a mechanic friend identified the problem (heater core)and he even gave me the amount it would cost within $3!

Does this car have an intercooler in the intake system? If there were a tiny crack in the intercooler a small amount of coolant may escape. As the intercooler warms and expands the leak might stop.

Wild theory, I admit, but I’m having a hard time figuring out how steam or smoke can escape from the hood scoop while the car is in motion unless the place from which the smoke or steam is coming is directly under the scoop, and the only thing I can think of that might be there is the intercooler.

This would also explain the slight coolant loss.

Have you tried starting the engine and watching under the hood as it warms up? Maybe you can see where the smoke or steam is coming from.

Thanks for the replies. Sorry, I see the smoke when I pull up to a stop light (the car is stationary).

Every time I stop at a stop light these days I am watching the scoop for smoke. Not what I had in mind when I bought a Subaru!?!

I will keep checking the coolant levels but it has been stable for a while now (>4 weeks) and the first mechanic said they had pressure tested the system.

Intercoolers exchange air not coolant. Not sure where idea of coolant is coming from.

You’re right, the Subaru uses an air-to-air intercooler. There aren’t many air-to-liquid intercoolers on cars any more, but there were a few in the past.

I said it was a wild theory. Now it’s an invalid theory.

My (wild) guess given the locality of the problem and knowing the turbo location vs intercooler is that one of the two turbo’s coolant lines is leaking a bit likely at the turbo itself.