General Weird rattling/ tapping noise

[cliffy71]

Hi , I’ve got a weird one here, when I start my car ( 2.4 ) from cold There is a weird tapping noise which seems to be coming from the cam cover area . It almost sounds like a belt hitting plastic .
The weird thing is after about a minute the revs start to drop ( sounds like the auto choke is turning off ) the noise then stops , it won’t make any more noise even if you rev it , the noise returns when it’s allowed to go cold And then re-started !!
Weird , any ideas ??? If it was a belt it would make the noise constantly!

 

[Abarth L]

Hi
If your oil level is low the hydraulic lifters will be "empty" and create a tapping noise,then after short time ( auto choke ) be quite due to oil been pumped into the lifters again.

 

[cliffy71]

Well I checked the Oil , it was full , started it up , no noise , just about to pull off the drive and the belt came off again ! One third of it shedded, I had just replaced the belt and tensioner 2 weeks before ,this is the third belt that has shredded in exactly the same place , has anybody got any thoughts as to what could cause this .

 

[Abarth L]

Well I presume you are talking about the aircon belt.
Inspect the pulleys surfaces, you moght have damaged it and now it is eating the belts.

 

[cliffy71]

I’m talking about the main aux belt , the one from the crankshaft pulley

 

[Abarth L]

On the crankshaft you have 2 belts.
1. On the outside mostly running horizontal to the front over the aircom pump.
2. Timing belt which run vertical to top over cam pulleys.

If it were no.2 Timimg belt then you would have damaged your valves since it would hit the pistons if that broke.

So I think belt no.1 broke. (Aircon)

Maybe you can post a picture?

 

[cliffy71]

It’s not the timing belt, it’s the main auxiliary belt (The long belt )that runs from crankshaft Pulley to the air con compressor, the belt from the air con compressor to the alternator is fine .
I will check all the pulleys at the weekend for damage .

 

[Maxcaddy]

just about to pull off the drive and the belt came off again ! One third of it shedded, I had just replaced the belt and tensioner 2 weeks before ,this is the third belt that has shredded in exactly the same place.

Without an obvious obstacle in the path of the belt's run, the likely cause is misalignment of the pulleys. However to shred a belt in 2 weeks would take significant misalignment, i.e. it would be very obvious to see with the engine running . So at his point in time it's somewhat of a mystery, noting that its not unknown for Magnetic Aircon pulleys to fail and wobble, but if that's what it was it would surely take the Alternator drive belt with it ???


.

 

[Abarth L]

And a picture tells a thousand words ?

Ok so the mistery has been solved ?

Look at the flow of the aux belt difference between your picture and mine.
The extra tention is what is shredding the belt.

The belt needs to go below the static pully.

 

[cliffy71]

Thank you , That’s very interesting, but the pictures my son pulled off google showed it the way I’ve done it,unless I’ve mis- interpreted it . I will check all pulleys for damage and re-fit belt your way

 

[cliffy71]

This is what it shows on the net

 

[cliffy71]

That’s how I’ve done it

 

[Abarth L]

This is what it shows on the net

Nope, this is not for the 2.4 Abarth, the image you have attached is for a coupé.

Also that extra tention might have shorten the life expectancy of the bearings on that aux system.

 

[Ralf S.]

It looks quite obvious to me. That belt is shredding because it's incorrectly fitted.

Look at the photos in Cliffy's post #7 .


The crank pulley has ribs on it. The balance shaft (?) pulley has ribs on it.

The belt must ONLY pass over the ribbed pulleys on its ribbed side. The bottom pulley in Cliffy's photo looks like it's ribbed, yet it had the smooth side of the belt on it. It's gonna die...

Abarth's photo is the correct routing.

*** The little graphic is wrong or for a different model.. although if you look closely, that graphic's bottom pulley is smooth. Yours is ribbed. ***

Ribbed face to Ribbed Pulleys.. smooth face to smooth pulleys. Then you will find the belt can only fit one way.


Tension will probably be okay, once you have fitted it correctly.


Ralf S.

 

[cliffy71]

I accept the belt may be on wrong but it seems funny it always shreds along the length of the belt about a third in from the engine face , I am currently running on two thirds of a belt situated on the pulleys away from engine face , so a third of the pulleys have no belt on ( the inside as you look at the engine thru wheel arch ) if that makes sense , I have previously ran the car for a year like this !
When I first bought the car the tensioner bolt sheared, so I had no reference to go off, and very little can be found online.I will get new belt tomorrow, inspect pulleys and put belt on the correct way , I’m sure I’ve tried and it wouldn’t fit , but I’ll give it another go

 

[Ralf S.]

One of the ribs is sharper or taller than the others and is cutting through the back of the belt, that’s all.

When you fit the new belt, route it over the ribbed pulleys and then pull it down as far as it will go over the tensioner pulley, enough so that you can get a 15mm socket/breaker bar or a long ring spanner over the loop of the belt.

Then rotate the tensioner clockwise as far as it will go (use both hands since it’s a beast and you’ll have zero leverage). Your glamorous assistant should then be able to just loop the smooth face of the belt under the pulley and you then just have to release the tension you’re holding on the bolt. It’s spectacularly simple after you’ve done it.

Be careful with the tensioner bolt and do t use an extension on the socket or it’ll fall off with much swearing.

Ralf S.