Originally Posted by leftlane
Thanks everyone - it appears that it is coolant, and my expansion tank is right at the minimum level right now. It isn't leaking very fast at all. I am concerned about the noise though - would a failing water pump make some kind of noise? It was almost like a rough exhaust brap at very low speeds - I at first thought I got something stuck under my car or on my tire. It went away with any revs at all.
I'll most likely flatbed it to my local indy next week. I don't want to make anything worse by having WP fragments running through the system.
Any ideas on costs to replace the expansion tank and/or the water pump?
Noises are hard to diagnose. If the tank is leaking the noise could have arisen from coolant leaking onto some of the accessory drive hardware.
It could have been something got momentarily caught in the belt/accessory drive system. Don't laugh.
Last Monday drove my Boxster 30 highway miles to the office. A few blocks short stopped to pick up some breakfast. The car sat just maybe 5 minutes. Upon restart there was a low pitched intermittent but regulator growling noise. The noise was slower than engine idling speed and slow enough that it really had me thinking a bad serpentine drive belt. But no warning lights and everything was otherwise ok.
I drove on to work and parked the car. An hour and a half later I was back at the car. I started the engine and the noise was still present. I decided to flat bed the car to the dealer (30 miles away) vs risk driving it.
After a 30 mile ride on the back of the tow truck and back on the ground with the SA and senior tech there I started the engine. Dead quiet other than the normal engine noise a healthy engine makes.
Since the car was due for a 5K mile oil/filter service I left the car there. Tech did the oil change and road tested the car. Still no noise.
We talked and left the car there another day during which time he checked the belt which was fine. No signs of rubbing, of coming apart.
The accessory drive pulleys showed no signs of rubbing by the belt and there was no bearing/shaft play. Even the water pump which has 138K miles on was fine. Not even any leak sign.
So I picked up the car one morning right when the shop opened and drove the car 30 minutes and got it fully up to temperature. Even stopped to fill the gas tank to duplicate the 5 minutes the car sat while I was getting breakfast back on Monday.
Even after the 30 minutes still no signs of the noise I heard Monday.
Both the SA and tech told me likely something blew into the accessory drive system. The SA and tech said they see maybe 5 to 6 cars a year in for noise suspected to be from the accessory drive area that proves to be non-reproduceable.
Have had the car back now this entire weekend and have driven it some with still no noise.
Just my way, my long-winded way, of highlighting how a noise may not mean anything at all.
But still to be *safe* I'd not risk a drive of the car. Any runnning the engine gets should be in the presence of a qualified tech with the goal of him making a quick and accurate diagnosis as to what is going on with the noise, if anything.
Besides the leak is real enough. Get that addressed. At the same time a check can be made of the accessory drive system. If it was truly the source of the noise the cause should be easy to spot.
Well, unless the source of the noise was something that momentarily got caught then got loose again. But if there is a real problem the tech will spot it.