Engine grind when driving

[Thoric]

Hi Everyone,

My wife owns a 53 plate Corolla 1.3 VVTi with 133k. It's a great car, we love its reliability. Very recently she's had a sudden engine noise issue that's intermittent but fairly worrying. The school run is about 2 miles, so the car performs 4 mile round trips twice a day, plus the occasional food shop trip (to give you an idea of the road usage). These short trips are enough to warm up the engine and when that happens sometimes this metallic grinding noise eminates from the engine bay. I've just taken the car out for a test drive to see if I could hear it and it took about 10 minutes of driving before it occurred, and it lasted for only 20 seconds, but it was awful while it was going.

My wife made a recording and I've put it on YouTube (ignore the tinkling noise at the end of the video - those are the car keys). You can hear a grinding noise in her recording. I heard the same thing during my test drive but perhaps not quite so loud. It's a weird grinding like a failed bearing, but the symptoms are odd:

1. It's not continuous - it comes then goes.
2. It never occurs when the engine is cold
3. When it happened to me I immediately started to slow down (country lane, I slowed from 40mph to about 10mph and it stopped sounding).
4. The pitch of the sound didn't change with speed (car speed or engine RPM)
5. The loudness of the sound didn't change either, it was equally loud at 40mph as it was at 10.
6. It doesn't appear to be affected by whether the brakes are being applied or not.
7. When making the noise there are no noticeable affects - ie there's no loss of power or braking effectiveness.
8. When it's not sounding the car seems like it always has been, no issues whatsoever.

I touched the wheels to test for temperature, in case it's wheel bearing or brake related. The two front steel wheels were hot to touch (but not unexpectedly hot), and the rears were cold (these are drum brakes). I guess this means my front brakes are doing all the braking work, perhaps they're not properly balanced, but that should be an unrelated matter, right? And they've probably been this way for many months and this noise is new and (seemingly) from the engine bay.

It's worth noting that I changed the fan belt about a month ago, without any problems. I didn't notice anything unusual and looking at the belt now it seems perfectly fine.

If it can't be made to happen often then I'm not sure how I can demonstrate it to a mechanic to get their opinion, so I was wondering if anyone on here had heard the same thing or had an idea what it might be? I'm hoping it's something I can investigate myself, I have a fair few tools and have worked on cars a bit in my lifetime, but without a clue of where to look I'm already stuck for ideas.

Thanks for reading, I hope someone can help, and I look forward to your replies :-)

 

 

[oldcodger]

While the brakes do seems an obvious source, the fact it does not change if you apply the brakes kind of discounts them.

Would suspect one of the idler pulleys on the aux belt.   If you replaced  the belt for a new tighter one, it might be that, thats showing up the bearing noise/wear once its gets warmed up ?

Slip off the belt and give both idlers a feel for play and smooth running; also check that little tensioner 'cylinder'  has minimal play in its connecting bolts.

Literally have both idler pulleys in front of me now as I can feel play on mine and do get sound rattley sounds from that side of the engine bay.

Think you will find your engine is a 1.4 or a 1.6,   1.3 on the older models.... ?

[Thoric]

Hi oldcodger,

Thanks. Firstly, yes, it's probably 1.4, my memory isn't what it used to be and given the capacity isn't written directly on top I can't quickly check haha

I took her out for more test driving this morning and got it to make this noise very regularly. It turns out it does stop when the car stops, and restarts when the car moves off again.

I took it straight home, jacked up the far side front corner and tried to turn the wheel. It was barely moveable.

So I think it's either the brake disc/pads or the bearing. Still not sure at this stage.

I took the wheel off and can see that the disc is pretty rusty (I can't remember when they were last changed, and the MOT was in February so they could have been ok back then but now warped/thin). They've had a good wire brushing and I've knock the rust off the rims and caliper housing, plus the rotor guard. I can now turn it, but in the meantime the disc has cooled down so it could still be either the bearing or the brakes. Ultimately I think we're due new front brake discs and pads (not looked at the pads yet but makes sense to change it all I guess), but I want to take it back out for a drive to see if the issue is the same. I'm hoping it's not a bearing, I don't have the equipment to change that :-/

I'll keep the thread updated with my findings!

[mickburkesnr]

If you can't move the wheel I would think it's a brake caliper that's stuck rather than a bearing.

[Thoric]

I think you're right mick. 

I cleaned up the rust as best I could, tried to take the caliper off to inspect but there's a rounded bolt head. Not amused. But it seems the pads are actually very worn, and when I rifled through the paperwork we can find no record of them being replaced in the last five years! So, given the knackered bolt is beyond my repair skills I took it to my local garage and they're replacing the pads and discs, so it'll soon be sorted.

During the clean up the rotor (disc) guard fell off, it was rusted through. So that's now absent and not being replaced - too much effort.

So I think the noise is either the pads or the rusted through guard. Not sure after all that, but glad it will soon be sorted out.

[Thoric]

Got her back from the garage. New pads and discs on the front. No more noise. So I think it was the worn out pads afterall. Sorted.