Many of you followed the saga of the noise coming from my timing belt area after I changed the belt and the water pump.

The noise eventually went away on it's own, and I think we determined with a pretty high level of certainty that the source of the noise ( metallic clicking at a uniform 16 Hertz ) was the water pump.

The water pump is a GMB, which I understood to be a pretty reliable company.

So why would a brand new water pump make noise like this which after a few hours of operation goes away on it's own?

  • A tight bushing on the main shaft. Commented Nov 24, 2016 at 11:46
  • @Pᴀᴜʟsᴛᴇʀ2 So that could cause it to initially make noise which then goes away after a certain amount of run time? Do you want to expand that into an answer? Commented Nov 24, 2016 at 14:42
  • It's just a "gut check" answer. Yes, just saying it was a bit tight and now has broken in a little bit so is no longer making any noise. I'm not saying I'd like it anymore with it now being quiet, but it seems the most likely thing to have occurred, IMHO. Commented Nov 24, 2016 at 14:48
  • A friend of my father has a great term for this; "It's just the newness wearing off" he says... Commented Nov 24, 2016 at 15:07
  • @SteveMatthews Is this a common occurrence? Just so I don't freak out next time and waste a bunch of everyone's time? Commented Nov 24, 2016 at 16:16

1 Answer 1


Water pump noise is not common but does happen. Steady tone noise is more common such as groans or squeals. Rhythmic noise is less common. There are three rotating parts in a typical engine water pump. Two standard type ball bearings and a spring loaded seal. The seal has flat faces that slide over each other. The seal material is often ceramic. The seal needs to slide smoothly, if there is extra friction a stick-then-slip rhythm can occur, resulting in noise. The spring in the seal can be the driver for the rhythmic nature of the noise.

New seals need some run time to burnish and hone the surfaces. Before this they can be noisy and exhibit some seepage.

This is what I learned from a pump seal manufacturing representative some time ago.

  • The thing is, that it seemed like it was the bearings making the noise because the frequency ( 16 Hertz ) matches the speed at which the WP pulley was turning. Commented Nov 24, 2016 at 18:04
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    I do not think the frequency rules out the seal nor rules in the bearings. Experience and research teach me that seals will wear in and quiet down but loud bearings do not usually get better with use. Commented Nov 25, 2016 at 5:57
  • Sounds good to me. Commented Nov 25, 2016 at 7:58

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