Technical Strange noise on heavy acceleration..??

[peterp]

Hi all
I've noticed over the last few weeks that when I accelerate from second gear on I can hear a kind of 'metallic,crunchy,whispery' noise which seems to come from engine bottom end.Goes away when I reach upper levels of rpm in each gear or when I take my foot off the accelerator...definitley louder when the engine is under stress,like on slight uphill in highter gears etc...
Doesn't seem to effect performance,though I'll need to monitor this.

Any ideas on what this could be...sorry for the description by the way..!!

Pete

 

[alexGS]

Could be a gearbox bearing. I take it you can't hear the odd noises while revving engine with car stationary?

Check the gearbox oil level...

-Alex

 

[peterp]

Hi Alex
Cheers-my first thoughts were the gearbox oil.Quite right too,no noises when stationery.
Without the benefit of the owners handbook could you please explain where I would the level indicator for this?Oh,and would this be responsible for the diffculty sometimes in getting it into 1st gear?

Thanks as usual for the help and advice.

peter

 

[alexGS]

I just happen to be online at the right time - for once!

The correct level is up to the fill plug on the front of the gearbox with the car parked on the level. It's just above and to the left of the reverse light switch. You may need a 12mm Allen key to fit it, with a few taps from a hammer to undo.

It's worth getting the original FIAT oil (ZC90) if you are new to these gearboxes There are alternatives - Castrol VMX on our market, don't know if that's available in the UK.

In our accessory shops, it's a minefield of old-style EP (Extreme Pressure) gearbox oils (smell of sulphur) which should be avoided. Unless - you have a later Mk2 Uno (with the push-down-to-select-reverse), some of these may use the 80EPX type of oil. Worth checking with your FIAT dealer. I rather get the impression that FIAT engineered the later gearboxes to 'tolerate' the more common EP oils; I don't believe that they 'require' them.

If really stuck, you can use engine oil (of a fairly 'heavy' weight such as 20W50). Better that than to risk damage from running low. However you may find that synchros don't work as well as with the FIAT oil (or, they may be fine - it's hard to say for sure, I've had both results).

EP oils, by the way, became necessary in the days of Hypoid Bevel RWD differentials, and the sulphur or phosphorus additives can have negative effects on bearings and synchros.

Common cause for low oil level is a leak from the driveshaft boots. The seal runs on the (swinging) shaft, and often wears a groove into the shaft. A new boot may provide a reasonable fix, but a replacement shaft would be better.

At least the correct FIAT oil is fairly cheap. Total capacity 2.4 litres (Mk1 gearboxes).

Cheers,
-Alex

 

[Chas Uno]

Hi all
I've noticed over the last few weeks that when I accelerate from second gear on I can hear a kind of 'metallic,crunchy,whispery' noise which seems to come from engine bottom end....definitley louder when the engine is under stress,like on slight uphill in highter gears etc...

If it's a sort of 'tinkling' metallic sound, and especially as you mention it is worse under engine load, then it could be 'pinking' (pre-detonation of the fuel). It could be something simple like you need to check/ adjust the ignition timing as it might be running too advanced.

Oh,and would this be responsible for the diffculty sometimes in getting it into 1st gear?

Uno gearboxes, especially mk1's, were never that smooth shifting and 1st gear can often be a bitch to get into! My gearbox was never that good (I seem to think that the 4 speed box in my old Uno was better for some reason ), so when I had to do a clutch change a few months back I took the opportunity to swap my gearbox for a spare 5 speeder I had. Result? Bugger all difference Well, maybe a little better at shifting gears, but then the original gearbox clutch arm was seized which didn't help matters. Strangely, sometimes it shifts gears really well, then other times it baulks. Like with you, it can be particularly stubborn getting into 1st, but all other gears seem to be ok.

I just put the 'reluctant' gear change down to 'character'