Water Pump, 2000-S40

[uhlan]

My S40 has been running rather rough for the past ~6 months. Not too terribly bad, but just enough to irritate me. Most noticeable when I'm, stopped and idling. I also notice what I thought was a sound similar to a small cheap air pump. Intially, I thought it might have been something like a vacuum leak or the like. Now I notice just a little bit of antifreee down beneath the front of the engine.

Does anyone think that a bad water pump could be giving me this rough idling and "~air wisping" sound?

[MadeInJapan]

When was your last tune up? How many miles on your S40? I ask because you say it runs a bit rough...usually a sign that you need new plugs, wires, rotor or cap, or even that the air filter needs changing. You might also check for leaking vacuum hoses. All of these could set a diagnostic trouble code that you can get read at auto zone for free (sometimes these codes get set without turning on your check engine light so it's worth checking out).
What you hear is probably a secondary air pump...it is fairly common on my S70 and it may be on yours as well...it tends to come on when the air/gas mixture isn't right and so it blows more air into the system- always at start-up and sometimes when you're stopped. It's no concern unless it sets a trouble code, then it could need servicing. In regards to the leaking coolant, yes, it could be your water pump but also check your larger hoses from your radiator. I've had mine leak a bit and needing tightening. If you don't see a leak from them, then you'll need to get under your car to see if it's coming from below the timing belt area (water pump). If you're close to a timing belt change then go ahead and get the water pump changed too along with your tensioner.

Good luck and let us know how things are.

[uhlan]

Thanks for the reply.

New plugs already in. May have helped somewhat but not enough.

Air filter? I do that about every 10-15K miles and looks real clean yet. So that 's not the issue.

Plug wires? Considered replacing them but they looked too good, so didn't think that was necessary. Above what Ohm resistance should they replaced?

Coil and rotor? Actually I didn't see these on the car (admittedly - don't recall looking). Also didn't see mention to this in the Haynes S40 repair manual, so suppected that my Turbo-Charged model didn't have them?

[MadeInJapan]

You are correct...no rotors or cap...your car has coil packs at the plugs. Sorry about that. Your wires may indeed be fine. A good way to check is to turn your car on in the dark and see if you see any electricity escaping them by arcing out as small blue electrical charges. If you don't see these, then most likely your wires are fine.

[uhlan]

Thanks for the reply. I feel much better that I didn't over look this rather basic potential cause to my problem.

Any thoughts on determining when the coils might be bad? That potential root cause to rough idling is suggested in my Haynes S40 book.