Technical Abarth engine noise (not normal)

[Ralph2]

The other day the wife complained about a noise from the engine. So far my investigations have found:
1) The noise is not there all the time
2) It is best described as a growling noise related to engine speed.
3) It appears to be coming from the cambelt end of the engine
4) I have noticed this end of the engine cover is much hotter than the nearside. It may have always been so, never compared it before.
5) A test drive just now only created the noise once, stayed for maybe 30 secs, then went again..
6) It seemed to me the engine was producing less top end power than I remember, but I rarely drive it these days so not 100% on that.

Does any of this ring bells with anyone? Loss of performance could be variator I know, but never heard of it making a noise. It is certainly not an exhaust noise, or intake for that matter. It is mechanical, quite interesting, the sort of noise I wouldn't mind all the time. But it deffo ain't right.....

 

[giggler]

if you are mechanically minded, i would remove cam cover and look.

 

[giggler]

also if it run's ok without cam cover, just test it, but avoid floods water, and refit, checking for no wear to the cover, and all bolts are secure. ps you may find it hasn't had a bolt re-tigthen'ed, and has jumped out, inspect the cam cover once removed.

 

[Davren]

Don't rule out the variator, there have been several posts about noisey variators on the 1.8 and 2.4 engines.

 

[Ralph2]

Well had the cam cover off, no evidence of any problem. If I was picky I'd say that No1 exhaust cam (Cambelt end) looked a little oil starved. Lobes were all OK though. Cam cover unmarked.

It's not like a diesel rattle as often described in variator failure. Tickover is perfectly quiet. The growl is most noticeable when dropping the revs towards tickover. Like a toy teddy bear growl, but not so gurgly, and deeper.

 

[Yellow Peril]

Belt pulley bearing?

 

[gadge]

I know you said it wasn't but from all that you have described, are you defiantly sure it's not an induction fault? Like maybe a problem with the VVI? I don't think it's the variator personally as like you say, they kinda "tick". Does it run lumpy?

 

[Ralph2]

I guess it could be either of those things (idle bearing/induction). I need to drive it some more to try and get a better diagnosis. If I could make it happen on idle, I might be able to pinpoint more accurately with the usual 'stick of wood to the ear' probe. Start, idle and run all sound fine. I could lean towards induction as it sounds similar to the 5 pot burble at low revs/wail at high revs. I see there are variator checks one can do with simple test gear so that's my next step. I also have ECUScan, does a shot variator throw up error codes of any kind?

Thanks for the suggestions guys , thinking by oneself can mean you miss the obvious.

 

[Ralph2]

Update: Extended test drive could not recreate the problem. Hooked up FiatECUScan and found a lot of stored errors due to my unplugging and replugging the looms. (One of the errors was P1653 Phase Variator.) Ran checks and tested the Variator relay and the V.I.S operation, everything working fine.

I tried the put the variable intake manifold in the wrong mode with the engine running to see if that was the noise, but ecuscan wouldn't let me. So now I have cleared all the fault codes and will see if the problem recurs. I'm wondering if the variable intake mechanism stuck in the 'power position' due to not enough use. Wife drives very conservatively, maybe I should take it out for a blast more often!

If I get any more information I will post it on this thread. Speaking from experience, logging resolved problems can be very helpful to others further down the line.