My local specialist has just told me that the misfire on my 53 plate WRX appears to be an exhaust valve issue - p0304 - (compression test 50psi vs 180psi on other cylinders).
Obviously this is an engine out issue while the cylinder heads are sent for some TLC.
My thoughts then run to clutch, belts, pulleys, water pump, alternator, etc. The car is completely standard and happy with that, but wondering what preventative work should be done while the expensive labour is already being paid.
Bearing in mind the car is probably worth less than £5000, I don't want to be spending excessive money.

 

I would Polish and clean the engine bay up etc but that’s just me

 

i would also look at engine mounts and possibly up pipe depending if you plan on modding it.

 

rear crank seal might be worth a look while its out as its a cheap part but engine or box out to do it

 

Me too.SJ.

 

Change the clutch and power steering fluid while you have easy access.

 

I changed to an rcm lightweight flywheel last time mine was out.

Might be worth doing the clutch too depending how much is left on it.

 

Just so you know, I had the same code come up because of a failing head gasket.

If the engine is out I'd at least change the belts, tensioners, thermostat and water pump.
Maybe get the turbo checked, depending on the mileage.