Duane, If the engine/compartment is dirty; Ie.grease/dirt/oil, Spray the area with a grease remover (aka. 'Gunk' from Cdn. Tire) or something similar first and let it sit for 5 minutes so it gets a chance to loosen the muck.
When pressure washing or steam cleaning DO NOT have the engine running. There is always the hazard of having water sucked up through the air intake and into the engine.
Don't spray water directly at the alternator or the fuse/relay box. You can (if you wish) cover these components with a plastic bag for the wash period, just remember to remove them before you re-start the engine.
Everything else, feel free to blast away at, using common sense of course. If in doubt, stay away from it. NOTE* after washing, check to ensure ALL the vacuum hoses, spark plug wires, etc. haven't been removed/loosened during the cleaning process.
When finished washing down, dry off the wiring with a dry towel/rag. Ideally, would be to use an air pressure nozzle and blow the entire engine/compartment dry.
Even so, there will be a drip-dry period after this. So let the car sit overnight and do a complete leak check the next day. Warm the engine up to the full operating temperature then shut the key OFF. You don't want the fan to start as the moving air will spread any leak to a different location and perhaps causing you to think THAT is where the leak is.
If you have an electric cooling fan be wary of getting any part of you too close to it as it can start at ANY time (UNLESS you disconnect the battery). You don't need to do that for the leak check.
The main thing is to make sure everything is dry before you start hunting for the coolant leak. You don't want to be under the engine checking for bad hoses or loose clamps and have water dripping on your face.
If you don't locate any coolant leaks anywhere (including the rad itself AND the drain valve at the bottom) with the engine shut off, Start the engine and look everything over again while the coolant is under more pressure and is circulating.
Check around the RAD cap. Is the cap on tight? If not, perhaps the gasket is worn and you need a NEW cap.
The heater core looks like the radiator core (the section which is all fins). Sometimes these leak causing a film to form on the inside of the windshield when the defroster is turned on. Other times the coolant will leak down the firewall and soak the carpet (on the passenger side).
At any rate, check the heater hoses where they connect at the firewall (passenger side, underhood).
If the heater core is leaking be prepared for a large labor intensive bill as the dash has to be removed to gain access. UNLESS your CIVIC has the heater core on the engine compartment side. (I doubt it) Have fun.
I'm sure Barrie will have some good ideas for you.
Duane, it's been my experience when having to repair something is to replace the old with NEW not used(?). Used is ALWAYS doubtful.
