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Okay here goes:
I have been chasing a rattle in my engine compartment. It started off really quiet several months ago and has slowly gotten worse. I have cleaned my vvti screen and OCV, replaced my belt tensioner and my drive belt (it needed it anyway.) I just did an oil change (it was due), replaced the PCV (for good measure, they're cheap anyway), and my timing chain tensioner (it was leaking). During the oil change I used some large hose clamps on a couple of heat shields around the exhaust just to see if that would help. It did not.
If anything, the noise has gotten worse after I changed the drive belt and tensioner. Today I put a big hose to my ear and stuck the other end in the engine bay with it running to try and isolate the noise. I think I read about this trick from this site somewhere... Anyway, according to the diagram above, the water pump seems to be making the most noise. Through the hose, everything is a dull roar until I get it up next to the WP pulley. Then it gets so loud that it almost hurts. I guess my last trick will be to remove the drive belt, start the engine briefly, and see if the noise has subsided. I'm just waiting for the car to cool off for a bit before I go sticking my hands down in there again. I should also mention that I never see the coolant temp spike. I have even data logged for 30min at a time and everything seems to be normal.
Anyone have any other ideas? The noise has become a very load rattling sound that can be heard from quite a ways away now. It can only be heard during idle or really low rpms while the car is stationary. It goes away completely at cruise, acceleration, or any other state of travel other then idle. Is it normal for a bad water pump to make a sound like this and still pump coolant? When I have found a bad water pump on other vehicles they make a loud whining sound, not a knocking sound like this...
2003 Spyder with 96k miles on it. I'm the second owner and have had it for the last 4.5 years. It is stock except for lots of bracing and a Che header. When I changed the oil, I sent it off for analysis. It just shipped out today, so it'll be a little while yet.
Any advice is appreciated! It's starting to drive me nuts! (By the way, what is the "VP" pulley in the diagram?)