Rough idle and coolant reservoir leak

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Ferroplasm
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Rough idle and coolant reservoir leak

Post by Ferroplasm »

NOTE THE ERROR IN THE TITLE. SHOULD SAY "COOLANT RESERVOIR BUBBLING"

I have two major mechanical issues currently afflicting my '06 Baja Turbo AT with 135,000 miles.

The first I noticed was a misfire on cylinder 4, CEL code P3004 (I think). I took it to an independent shop and they replaced the coil pack and spark plug for that cylinder. They told me the plug was badly fouled. This was at the beginning of June. The CEL has not turned back on but the repair did not resolve the engine shake at idle. I took it back to that shop and they admitted they were unable to perform an more extensive repair as they were unequipped to do so.

Took it to the dealer and they found that the shop did not use genuine Subaru parts, no surprise, and recommended replacing the coil pack on cylinder 4 and spark plugs on cylinders 2 & 4 with genuine Subaru parts. I received the car back yesterday and there's no improvement whatsoever. The technician noticed some bubbling in the coolant reservoir and suggested there could be a minor head gasket leak. He also suggested the engine roughness at idle could be due to poor valve adjustment. I asked about them performing the valve adjustment and they said it probably isn't worth doing unless I also do the head gasket. Head gasket + timing belt repair was quoted at $4800 (yikes).

I declined to have the head gasket or valves repair at the moment. I need to decide whether the cost to do these repairs makes any sense on a 15 year old vehicle with a resale value less than $7k.

Here's my question, are there any additives I can use as a temporary stop-gap? I was thinking possibly Marvel Mystery oil to loosen any valves that might be stuck and also the Subaru OEM Coolant System Conditioner to possibly seal the minor head gasket leak. Thoughts?
SupeRoo Baja
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Re: Rough idle and coolant reservoir leak

Post by SupeRoo Baja »

That sounds like a head gasket leak.. is there white smoke out the tailpipe?

Wait till engine is cool, take radiator cap off, and start the engine.. if you get bubbling at the radiator, excessive white smoke out the tailpipe, or coolant/oil mixing (coolant will have oil floating, or be milky colored), then it's for sure a head gasket.

You Could do a Cyl#4 compression test as well just to verify low compression or water in cyl. This is normally the Cyl that pops due to heat build up. ( I did a Cyl#4 coolant bypass mod and aluminum radiator.. the fans don't even kick on anymore at idle it cools so fast.)

Now, the Turbos normally didn't have this issue due to the 'correct' head gasket being used.. but not impossible to blow one.

However, 4500+ is ridiculous for that repair. I got a whole new engine from CISR for 3k, with the turbo head gasket fixes and such. (This was an N/A, but I do think the turbo engine was about same cost, w/out turbo obviously)

Heads can be re-done while the engine is in vehicle, but is harder to pull due to clearance. Much ezr w/ engine removed. I would shop around to get prices.

Good Luck!
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