Technical Gearbox Leak

[Idleboy08]

Hi guys

I'm looking for a bit of advice. I have recently topped up my gearbox oil as it seemed very low. I'm not exactly sure how much was in (nothing came out when I removed the plug) so put a full 1ltr in. Anyway, I have noticed that oil has started to leak from the boots on both sides (see picture). Do you think this is just overfill? I can't see any obvious damage to the boots. Is there away of checking? Any advice would be appreciated

 

[fiat500]

On level ground you need to unscrew the square plug that is just about in the centre of your image, just behind the leaking boot. It is probably overfilled and this will allow the surplus to come out.
You probably do have worn seals onside the boot and that might explain your low oil in the first place.
Incidentally, where did you fill it up?

 

[Idleboy08]

Hi Peter

Thanks for getting back to me. I filled the gearbox up by running a pipe from the engine bay, as I've only got axel stands and could get enough high from under the car. Like you say I think the first think to do is to remove any surplus by removing the plug and letting it drain out.

Is it a difficult job to change the seals inside the boot and would you change the boot at the same time?

 

[fiat500]

Hi Peter

Thanks for getting back to me. I filled the gearbox up by running a pipe from the engine bay, as I've only got axel stands and could get enough high from under the car. Like you say I think the first think to do is to remove any surplus by removing the plug and letting it drain out.

Is it a difficult job to change the seals inside the boot and would you change the boot at the same time?

The square, level plug is technically also the filler plug.

The seals are quite easy to remove and replace although it gets a bit involved. Basically you remove the four hex screws holding the flange at the wheel end of the drive shaft, remove a circlip on the shaft and then the flange. There are four small hex screws holding the securing plate for the rubber boot at the gearbox end and removing those lets the rubber boot slide off the shaft. The seal is in a carrier which is held by friction inside the rubber boot.
If the boot is in good condition I would retain it and fit a new seal in the carrier as the modern ones are useless in my experience.
It's worth getting good at this job as it is a favoured problem area for the 500.
https://www.fiatforum.com/500-classic/422377-seriously-no-gearbox-fluid-leaks-2.html

 

[Idleboy08]

Hi Peter

Brilliant - that is really useful information. I'm pretty good with the spanners so I'm confident I'll be able to do this task myself. Once again, thanks for taking the time to get back to me.