Diagnosing squeak/squeal from timing belt area (suspect water pump)

**h4l** · 24-10-2015,04:24 PM

Hey, I'm trying to pin down the cause of a squeak/squealing noise from my engine. It's a 1.6 AZD code.

The noise is a high pitched squeak/squeal which is continuous, but oscillates up and down a little in volume and pitch a few times/second. Here's what I know:

1. Only starts once the car is fully up to temperature.

2. Only happens at idle, as soon as the RPM raises it stops. Turning on the AC raises the RPM enough to stop it.

3. I've tested various areas with a mechanic's stethoscope. The loudest areas are:

the water pump body itself
the plastic coolant manifold on the opposite side of the engine to the water pump (but there's a pipe going straight to it from the coolant pump)
the small idler pulley which is connected with the same bolt as the water pump

I can't get the stethoscope to the idler pulley below the water pump as as only the top timing cover can be removed without taking off the crank pulley...
None of the aux belt pulleys are loud with the stethoscope.

4. When the coolant gets hot enough for the fans to kick in, the squeaking gets louder as the fans run then gradually goes back to old volume level over 30 seconds or so.

6. If I (carefully) take off the coolant expansion tank cap when it's hot and squeaking, the squeak gets a lot quieter and almost stops.

To me it points to the water pump failing. I replaced the pump with a genuine VW one 4 months ago after the previous one started leaking. Anyone know if these pumps do fail by squeaking like this, or have any other ideas for what it could be? Anything else I can do to confirm it's the pump?

I spoke to my VW dealer (where I got the pump from) and they said they'd replace and fit it under warranty (even though I'd fitted it), but if it turned out not to be the pump I'd be liable for the cost.

Many thanks.

**zollaf** · 24-10-2015,04:31 PM

it does sound like the pump. try taking the aux belt off to rule out anything driven by that, then make certain nothing is touching the lower belt cover. even go so far as taking the crank pullley off, removing the cover and obviolsy having a feel of the pump, then replace the pulley and start her up, see what happens.

**h4l** · 24-10-2015,04:40 PM

Cheers, I'll give it a go. Only concern with the crank pulley is that the crank bolt is supposedly a 1 time use stretch bolt, and I've always replaced it in the past. Should I worry about this? I guess it's not going to run for long before it's off again to be replaced anyway.

**zollaf** · 24-10-2015,05:01 PM

indeed, don't worry. its like an inch thick, you won't snap it.

**Rob69** · 24-10-2015,05:12 PM

I replaced a pump in a hurry and reused a big bolt on a 1.4 polo and it ran for another 18 months and 15k until I next did the belt.

**h4l** · 24-10-2015,06:21 PM

OK, thanks, I'll whip it out then. I've just had the aux belt off after warming it up and the noise is still present with the aux belt off.

**Rob69** · 24-10-2015,06:56 PM

Carefully check the belt edges for fraying, tensioner and idlers for any misalignment, belt maybe being overtensioned and bottom belt cover rubbing as you get the pulley off and further in towards the pump. I'd say it's pretty rare for a new genuine pump to be faulty after a few months. When my pump went after 70 odd k, it gave an intermittent rumbling noise, then started leaking badly very quickly. The bearing was shot, It didnt squeek, not to say that your squeeking isnt the new pump though.

**h4l** · 24-10-2015,09:29 PM

I've been looking over the belt and pulleys. No sign of any rubbing of the belt, no marks at all on the inside of the lower cover.

The tensioner pointer was slightly lower than the middle of the cut out, so slightly low tension.

The belt looks OK to me, it's 2 and a bit years & about 25k miles old. A little bit of fraying on very close inspection, do you think it looks ok? (See the photos below).

I've listened to all the pulley bearings with the stethoscope, the big idler and the tensioner sound the smoothest. The water pump sounds a bit rougher, but can't hear anything with the naked ear. The small idler pulley above the water pump sounds the roughest, you can hear a bit of roughness with the naked ear. It also has a little bit of visible play if I grasp it and move it around. The water pump has a tiny bit of play if I pull it back and forth, but so small that it's not visibly moving, you can just feel a tiny movement.

Can't get anything to squeak by manually pushing/turning.

Here are some photos: http://imgur.com/a/SdipC

The small idler seems like the weakest link at the moment...

**zollaf** · 24-10-2015,11:11 PM

so you replaced a water pump but didn't replace anything else , like the belt or pulleys ? last time the belt was replaced, 25k go, were all the pulleys and tensioners replaced. to me that belt looks like its scrap, the fraying on the teeth looks terminal. i would suggest a new belt and kit. its probably the guide roller thats squeeking.

**h4l** · 25-10-2015,12:04 AM

Correct, I changed both timing belts, all pulleys and the water pump 2 years/25K miles ago. It was an SKF brand kit. Water pump was Circoli. A few months ago the water pump started to leak so I swapped it for a VW one.

I think you're right. The guide roller certainly needs changing, so I might as well do it all. I'm surprised that the belt would be damaged and the pulley wearing out after this length of time/mileage.