Squeaking while engine is cold & at low revs

[Richard Davies]

I have a 2001 1.3 Yaris & recently it's started to make a squeaking noise when the engine is cold & running at low revs.

Once the engine is over about 2000 RPM it goes, & after the engine has warmed up it doesn't come back even when idling.

A quick search on here comes up with other Toyotas (couldn't see it on the Yaris forum) having similar problems.

On one of these threads someone suggested it was an alternator belt that needed adjusting or replacing.

[MikeSh]

Quite possibly the belt. Also the easiest to check and fix, so eliminate that first.

Quick test: before starting pop the bonnet, check how to get to the belt and have a can of WD40, with extension nozzle fitted, in hand. Start the engine, listen to squeak, squirt a bit of WD40 onto the inside of the belt or the contact face of a pulley (obviously keep ties, fingers, etc, out of the moving parts). If the squeak stops - it's the belt. Then decide if it needs adjusting or replacing (condition? tension?). If the noise doesn't change it's something else, maybe water pump or alternator.

 

[Richard Davies]

OK I'll give that a try

 

[bathtub tom]

Please don't use WD40, it contains a small amount of oil and if it is the belt slipping then oil ain't going to improve it! If the WD40 does make a change, then you've got an oily belt that you'll definitely need to replace.

I'd recommend water. If that quietens it then you can tension it a little tighter (if you can) and the water will disperse.

It's quite common at this time of year to experience belt slip. Tired, old batteries combined with use of heated rear windows and glow plugs on diesels puts a lot of extra load on alternators and belts that haven't had to do much since last Winter.

[Cyker]

Almost certainly one of the belts; Very very common issue on the Yaris Mk1 as they get older.

 

There are two belts - One that drives the alternator, water pump and A/C (If you have it), and a second smaller one that drives the PAS hydraulic pump.

If they've not been changed for ages (Or at all), I'd recommend getting both changed and retensioned, otherwise just retensioning is probably enough.

 

[Richard Davies]

I'll get it checked out, the Battery was new this summer but the alternator belt is a few years old.

[Mooly]

Its actually new batteries that put more load on an alternator, not old ones.

In an old one, the internal resistance has increased (which is why it struggles to supply current to start the car) and that factor also works in reverse, it is unable to take in much current when presented with the charging voltage from the alternator. The new Battery takes as much as the alternator can supply current wise for a short time after starting as the charge is replaced. That heavy loading makes the alternator harder to turn, hence the belt can slip.

When I had my Corolla TSport, that developed a squeak after starting from cold and the culprit was the tensioner pulley for the belt. I cheated and mixed some grease and oil together and then trickled that down the blade of a long handled screwdriver into the opening on top of the pulley. Plenty of paper  towel to absorb what ran through and out the other side onto the pulley. That one off 'fix' was 100% successful throughout the 8 yrs I owned the car, the problem starting around 3 to 4 yrs old.  

 

[MikeSh]

On 15/12/2016 at 11:05 PM, bathtub tom said:

Please don't use WD40, it contains a small amount of oil and if it is the belt slipping then oil ain't going to improve it! If the WD40 does make a change, then you've got an oily belt that you'll definitely need to replace.

WD40 is not a significant lubricant. It does light duty for a while but rapidly evaporates/disperses. I've done this trick with belts many times over 40 years or so and it's never been a problem ... well, only to the extent that within a few minutes to a few days the belt starts squeaking again. It's purely diagnostic.

[bathtub tom]

From Wiki:

Formulation    <25% petroleum base oil. Presumably a mineral oil or light lubricating oil.

I wouldn't want to put anything that's 25% oil on a belt that depends on friction.

[Richard Davies]

I've now sorted this out be replacing the belt as the old one was looking worse for wear.

[Mooly]

Pleased  to  hear you've sorted it and that it was as many suspected just the belt.