Technical Irregular rattle from accessory belt and sluggish turnover speed

[Poperon]

Hi,

A couple of weeks ago there was a horrible irregular rattle coming from the accessory belt area. Worst on cold start up and gets quieter when the engine has warmed up (but never quite goes altogether).

Also, for the past couple of years the speed of engine turnover when starting has been sluggish.

So today I put it up on the ramps, took off the under engine cover and sure enough the noise was coming from this area.

Took the accessory belt off and started the engine...noise had gone...and the sluggish turnover speed was back to how I'd expect it to be.

Something here is causing the rattle and sluggish turnover.

The belt and tensioner are 2 years old and still good.
The steering pump turns freely (slight oil weep from here)
The alternator turns freely
The AC pump turns freely, but there is a very slight rattle from the pulley when bashed with a hand (clutch mechanism?)
The crankshaft pulley looks ok.

I'm missing something, baffled.

Any ideas on both counts much appreciated.

Cheers

Ron

 

[bugsymike]

Power steering should only be under load when turning steering so probably not that , ditto air con.
My suspicion would be the alternator, when started can you put a "listening stick" against it safely to hear any strange noises?
A further test may be to see if noise gets worse with headlights etc. on, electrical loading.

 

[Poperon]

Thanks Mike,
My plan is to firstly eliminate the AC pump by fitting a shorter belt to bypass it, if its not this then I'll get my auto stethoscope on to the alternator as you suggest.
Thanks
Ron

 

[bugsymike]

Generally if aircon off the pump clutch should be disengaged so it can freewheel, I have heard of alternator armatures delaminating I think it is and dragging on the sides of the casing as the start to fail.
If it was just a rattle I would go for the aircon pump clutch as I have had that on customers cars in the past but I can't see that causing sluggish turnover when starting.

 

[Poperon]

Hi,

One thing I did notice before taking off the belt was that there was quite a bit of up/down movement/oscillating of the belt tensioner.

Could this be due to the alternator pulley packing in?

Cheers

Ron

 

[varesecrazy]

Hi Ron,

Seen a few cases of laboured cranking being down to the alternator..

Could you wind a string around the pulley and spin it like a mower starter..?

That will highlight:

Resistance
Vibration : noise
Pulley runout

 

[bugsymike]

The old screwdriver stethoscope trick if you can access safely may help pinpoint it.
I have not seen that but if alternator trying to jam it could cause the tensioner to kick about.

 

[Poperon]

Hi and thanks,

At the moment it's pouring....when it dries up (tomorrow?) I'll have another look.

Cheers

Ron

 

[Poperon]

Hi and thanks,

It stopped raining....

First thing was to check every pulley/tensioner/idler with the string trick. All are free running and no signs of arthritis.

Next I did the freewheel test on the alternator pulley. This works as it should.

Finally, I had a look at the new belt (replacement 2 years ago) and compared it to the original old one. The New one is now 4mm thick and the Old one is 5mm. The New one looks like the points of Vs have been shaved off (accounting for thickness difference).

Could this be anything to do with the noise I'm getting and possibly sluggish starting. I'm thinking that the belt gets firmly wedged into one or all the pulleys?

Cheers

Ron

 

[Poperon]

Oh, another thing. The v grooves on the steering pump, alternator and crankshaft pulleys all look clean without any rust. However, the AC pulley is a bit rusty at the bottom of the grooves and my guess is that this is like sandpapering the v-belt.

I'm thinking that seeing as the AirCon packed in a few years ago and never got used before that I could bypass it with a shorter v-belt and remove the fixed idler.

Any thoughts much appreciated.

Cheers

Ron

 

[The Panda Nut]

Our Panda 169 does / did this exactly as described. I have repeatedly soaked the alternator bearings with all manner of light lubricants, sprayed on with the engine running. We had the cam belt changed and likewise were told everything in order.... Anyway since the idlers were cleaned and the alternator oiled while access was good its now been quiet for months. Famous last words. Dry alternator bearings can run as smooth as silk for ages and then get out of phase and cause mayhem. Its where I would go, then the cambelt and aux belt idlers.

 

[jackwhoo]

The vees of the belt should not reach the bottom of the pulley grooves . The flanks of belt vees transmit the drive.

 

[bugsymike]

You may have a problem bypassing aircon compressor depending on how the guides are positioned on your vehicle, so that the belt doesn't foul something else.

 

[Poperon]

Hi Mike,
Many thanks for the photo. I had studied ePer drawings for my engine, there are variants for engines with air con and those without. To bypass the AC pump I plan to remove the fixed idler and fit the belt sized for the non AC engine. Lets hope it works!
Cheers
Ron

 

[Poperon]

Hi,

This is definitely a game of snakes and ladders.

Fitted the shorter belt....noise still there. Damn.... That eliminates the AC pump.

Took off the crank pulley, it seemed to be running true when on the engine and generally looked ok on the workbench.
But, there were marks on the back of the pulley where it had been incontact with the plastic cambelt cover. What's odd is that there's a good 2mm gap between this cover and the inboard face of the crank pulley when the engine is running.
I'm not too sure what to look for in a failing crank pulley. The rubber bits all look OK and it flexes a bit when shoved about. There's a bit of a ring (metal on metal sound) when tapped by hand on its face.

To me it looks OK but can any of you experts confirm this or tell me how to check it properly?

Cheers

Ron

 

[creon]

Couple of years ago the aux belt tensioner broke off on my doblo and took the aux belt with it, I replaced both. Then with the new equipment there was a metal rubbing clonking noise I was a bit lost. Belt off no noise belt back on noise.

Anyway the tension from the new belt etc was putting strain on the old crankshaft pulley so I replaced it with a cheapo noise gone.

The other month the clutch on the alternator pulley seized so I replaced and put a new belt, I've now got the same metallic noise. I'm replacing the crankshaft pulley again tomorrow with a febi branded part, I'll see how it goes.

The OEM crankshaft pulley are known to fail in 2 years apparently.

I should've gone to the scrappy but for some unknown reason there's a scarcity of Fiat there but Saab and GM use the same pulley.

Maybe the torsion vibration damper has failed on your pulley?

 

[Poperon]

Hi,

Thanks.

I had heard that the crank pulleys do go but I can't see anything wrong with mine, the rubber bits all look sound.

My latest suspect is the steering pump, it's been leaking for sometime and I tried some "Lucas power steering stop leak" a couple of years ago. It worked for a time but the leak came back.
I've got an auto stethoscope and everything in the car sounds bad! However when touching it on the steering pump from behind the diesel pump it seems like the noise I mentioned earlier was coming from here.
Yesterday I got the pump out and there's definitely noise coming from inside it and there's also a few millimetres of end float. So, at the moment I'm trying to find an ok aftermarket one to replace it with.
If it doesn't stop the noise then I'll probably be on replacing the crank pulley.

Cheers

Ron

 

[creon]

Hi,

Thanks.

I had heard that the crank pulleys do go but I can't see anything wrong with mine, the rubber bits all look sound.

My latest suspect is the steering pump, it's been leaking for sometime and I tried some "Lucas power steering stop leak" a couple of years ago. It worked for a time but the leak came back.
I've got an auto stethoscope and everything in the car sounds bad! However when touching it on the steering pump from behind the diesel pump it seems like the noise I mentioned earlier was coming from here.
Yesterday I got the pump out and there's definitely noise coming from inside it and there's also a few millimetres of end float. So, at the moment I'm trying to find an ok aftermarket one to replace it with.
If it doesn't stop the noise then I'll probably be on replacing the crank pulley.

Cheers

Ron

Ye the rubber on mine also looked fine

 

[Poperon]

Update:
It was the crank pulley after all, thanks @creon.
First I replaced the steering pump, it was already leaking from the main shaft. Noise still there, leak gone and sluggish starting definitely better. I think it was worth all the effort.
Then replaced the crank pulley, noise gone. Who would have thought that it could make such a racket when it looked ok, well it did to me.
Thanks for all the help
Ron