Hi,

Tried to top up the oil on my wife's fiat 500 today and cannot undo the oil cap! :bang:

It's not stuck and I can turn it but it just keeps clicking. If I turn it clockwise or anti clockwise I get the same noise. It is harder to turn as if I was trying to undo it though but it still clicks.

Has anyone had this problem? Google shows no similar experiences. I'm wondering if it has been tightened up wrong and has somehow managed to cross thread??

Any help would be appreciated, thanks.

Your 500 has a 0.9 TwinAir engine?

Blu500 said:

Hi,

Tried to top up the oil on my wife's fiat 500 today and cannot undo the oil cap! :bang:

It's not stuck and I can turn it but it just keeps clicking. If I turn it clockwise or anti clockwise I get the same noise. It is harder to turn as if I was trying to undo it though but it still clicks.

Has anyone had this problem? Google shows no similar experiences. I'm wondering if it has been tightened up wrong and has somehow managed to cross thread??

Any help would be appreciated, thanks.

Click to expand...

Hello and welcome.

The oil filler cap has a built-in friction ratchet, which clicks when tightening (to stop it being overtightened). It should not click when untightening - it seems likely that yours has got a worn or damaged ratchet mechanism.

Try undoing it when the engine is either at running temperature, or stone cold. It might firm up in the cold weather, so trying first thing on a very cold morning might just do the trick.

Once you've managed to remove it, I'd say the best and safest thing to do is to replace it.

Don't try driving with it removed - the mess it will make of your engine bay would have to be seen to be believed.

Ok, I realise the following link is for a Jeep, but this might be a solution if you don't succeed with other methods:

http://www.stu-offroad.com/engine/oilchange/oilchange-3.htm

Clearly, anything you try is at your own risk

frupi said:

Ok, I realise the following link is for a Jeep, but this might be a solution if you don't succeed with other methods:

Clearly, anything you try is at your own risk

Click to expand...

Looks worth a try, though I'd buy a replacement oil filler cap first.

If you are in any doubt about being able to remove it cleanly without anything falling into the engine, I'd suggest also buying a new gasket, removing the cam cover and extracting the old filler cap on the bench.

My oilcap (TA) has always been difficult to remove, in fact It can't be undone by hand if tightened past the first 'click' and I have to use pliers. I suspect one day it will do the same as this due to the stress so I only tighten it to just short of the first 'click' now. It hasn't shown any inclination to come loose and I still sometimes need the pliers to get it moving.

Piccolo Nero e Bella said:

My oilcap (TA) has always been difficult to remove, in fact It can't be undone by hand if tightened past the first 'click' and I have to use pliers. I suspect one day it will do the same as this due to the stress so I only tighten it to just short of the first 'click' now. It hasn't shown any inclination to come loose and I still sometimes need the pliers to get it moving.

Click to expand...

With your words ringing in my ears, I went out to check mine.

I very nearly panicked!

It took all my finger-strength to turn it. Never had a problem before, but this morning was damned cold and I would normally have undone it with the engine still warm.

Maybe when the engine block/head/etc is stone cold, it's tight, and when warm, it's not so tight?

Thanks,
Mick.

Mick F said:

Maybe when the engine block/head/etc is stone cold, it's tight, and when warm, it's not so tight?

Click to expand...

The thermal coefficient of expansion for aluminium is very different from that of most plastics, so I'd expect the fit to be temperature dependent.

Linear temperature expansion coefficients ((10-6 m/(m K)):

Aluminium: 22.2
ABS: 73.8
Nylon (general purpose): 72.0

If you get into the habit of always opening the cap under the same conditions, it might help prevent this sort of thing from happening. If yours is stuck, try any combination you can think of - one of them might work! You could even try wrapping the cap in a packet of frozen peas when the engine is warm.

Damn ....thats too technical for me at this time of day !

Yep, my TA's cap has been very tight on occasions, but I've always (just) been able to undo it by hand. When I tighten it, I only let the ratchet click once, but I'm not sure if that's any different from multiple clicks!

Thanks for all the replies.

I have tried it when cold and at running temperature still no luck. If I twist it really hard I can see and feel the plastic cracking a bit. So as said the Rachet system must have failed.

We have booked the car in for a service on Friday at fiat as its due one so will report the problem then and see what they can do.

I feel that I will have to break it to get it off and don't fancy doing this without a replacement handy also with the risk of something falling inside I think it's better to leave it to the professionals

Blu500 said:

Thanks for all the replies.



I have tried it when cold and at running temperature still no luck. If I twist it really hard I can see and feel the plastic cracking a bit. So as said the Rachet system must have failed.



We have booked the car in for a service on Friday at fiat as its due one so will report the problem then and see what they can do.



I feel that I will have to break it to get it off and don't fancy doing this without a replacement handy also with the risk of something falling inside I think it's better to leave it to the professionals

Click to expand...

Hmm be careful with that, you may run the risk of bits falling in alright, I wouldn't risk it

I had trouble removing the oil filler cap, the ratchet kept slipping so I wound a large self drilling screw into it to trap both halves of the cap. I still had to use pliers to get it out, very tight. See pic.

Ripley said:

I had trouble removing the oil filler cap, the ratchet kept slipping so I wound a large self drilling screw into it to trap both halves of the cap. I still had to use pliers to get it out, very tight. See pic.

Click to expand...

I hope you're not still using the faulty cap? and its just the new one is a tight fit?

This helped me remove the top part of the cap with a plyers. Then I was able to unscrew the remaining part of cap. This worked with my Fiat 500 twin air also will work with panda twin air or Alfa MiTo twin air.

I had a similar problem on my new (2013) Twin Air - used pliers to get enough grip/torsion (?) to undo.

Wondering if it's worth replacing the oil cap, anyone know if these are easy enough to come by?