Honda Civic - mysterious noise




I have a 2000 Honda Civic with 70K miles that has been making a noise that I can’t figure out. About a year ago, I began hearing this medium-pitch hum in the 1500-2000 rpm range, only after the car has warmed up for a few minutes. I was told that it was probably the water pump, so I took it to a mechanic and had the water pump and timing belt replaced. The mechanic confirmed that the pump was bad and the noise went away.

A few months later (just after the labor warranty expired, of course), the water pump started leaking coolant, so I took it back to the shop and they replaced the water pump. After that, the original noise came back.

Frustrated with the original mechanic, I took it to the Honda dealer, as I should have done in the first place, and their shop diagnosed the problem to be the water pump. So, I took it back to the shop again, this time completely under warranty, and they replaced the water pump again. However, the noise did not go away.

Just today, I took the car to Midas for an oil change and asked that they diagnose the noise. They suggested that the noise was the timing belt.

I talked to a knowleadgeable person about the noise and he suggested it might be the tension on the water pump belt causing a noise in the bearing in the water pump, but of course this can’t be investigated without a significant cost.

Any help on this problem would be much appreciated.



When you had the timing belt/water pump changed did they replace the belt tensioner and idlers?
I would guess that either the timing belt is to tight or you have a idler or tensioner bearing going bad. I understand the cost to tear it down and find the noise is expensive but not as expensive as it would be if the bearing goes out. If it does it will shred the timing belt causing internal engine damage.
~Michael (dartman69)


Thanks for your response, Michael. I don’t think the belt tensioner and idlers were replaced. Would the tensioner have been adjusted during the course of installing the water pump? This might explain why it went away and then came back with the 2nd water pump installation.

One other piece of information that I left out is that the noise has not changed or gotten louder during this time.