Technical Oil leak issue classic fiat 500

[DDW1982]

Hi to all

My classic fiat 500 (running a 650cc engine) and a fiat 500R gearbox has developed a leak from the bolts as shown in the attached picture. The vehicle is an immaculate show car and has done around 5 miles in past 4 months (as an idea for how little it’s used). I’ve contacted some parts companies here in U.K. for advice who say they have never had anyone report a leak from this area before.

Has anyone else every experienced this?

Thanks in advance for help and pointers

 

[bugsymike]

Speaking as a retired motor engineer with no model specific knowledge I would say for oil to be running from those bolts that the gearbox reconditioner either didn't fit a correct gasket or used sealant instead and did not go around the bolt holes when applying the sealant. Other than a crack which seems unlikely at both bolt mounting points, I suspect as above.
I see bolts all appear brand new with new split locking washers, is it possible the originally came with flat sealing washers as well as the split locking washers?
If only place leaking you may be able to make a practical solution by removing bolts and placing copper or Dowty washers on them and refitting, check gearbox oil level and give good long retest so oil gets hot and thinner to show any leaks.
Another point on looking at your photo there appears to be black sealant on part of the gearbox flange which doesn't look like it came from a Fiat factory which also points towards my original thoughts.
Other Forum members may have more specific advice.
One small point, if that is the cause, other bolts higher up may start to leak after longer journey.
If top of car resembles the underbody then I certainly agree with you re your statement "immaculate show car"

 

[DDW1982]

Speaking as a retired motor engineer with no model specific knowledge I would say for oil to be running from those bolts that the gearbox reconditioner either didn't fit a correct gasket or used sealant instead and did not go around the bolt holes when applying the sealant. Other than a crack which seems unlikely at both bolt mounting points, I suspect as above.
I see bolts all appear brand new with new split locking washers, is it possible the originally came with flat sealing washers as well as the split locking washers?
If only place leaking you may be able to make a practical solution by removing bolts and placing copper or Dowty washers on them and refitting, check gearbox oil level and give good long retest so oil gets hot and thinner to show any leaks.
Another point on looking at your photo there appears to be black sealant on part of the gearbox flange which doesn't look like it came from a Fiat factory which also points towards my original thoughts.
Other Forum members may have more specific advice.
One small point, if that is the cause, other bolts higher up may start to leak after longer journey.
If top of car resembles the underbody then I certainly agree with you re your statement "immaculate show car"

Thanks very much indeed for your thought and input. I’ve read through a few Fiat 500 manuals and can’t find anything relating to this part to know if there are missing or incorrect washers.

Yes the car is completely immaculate. Had full restoration few years back which is why I’m surprised I have these issues with “new” parts.

Thanks very much for your pointers though sir, I shall indeed investigate further

 

[Goldnrust]

The use of sealant between along that join between the bell housing and rear half of the gearbox is correct, there is no gasket. It's common for the bell housing to need to be separated from the gearbox when driveshafts need replacing, or when fitting 650cc engines that need a different bell housing (not sure what bell housing design the 500R uses). Either way, I'd be very surpassed if yours has not been split at some point.

As already pointed out, the black silicone there that has been used is a bit messily applied, and possibly that suggests that it wasn't applied correctly around the inside edge of the bolt holes, which is allowing the fluid to seep through by the bolt heads.

The only 'real' fix would be to split the gearbox, and re-seal it. A rather major job for, what I presume is, a small leak! You could try various other bodges to try and seal the bolt head, either with a sealant under the bolt head or a sealing washer.

I doubt it's going to do anything other than weep a little, personally I'd not loose too much sleep over it!

 

[DDW1982]

The use of sealant between along that join between the bell housing and rear half of the gearbox is correct, there is no gasket. It's common for the bell housing to need to be separated from the gearbox when driveshafts need replacing, or when fitting 650cc engines that need a different bell housing (not sure what bell housing design the 500R uses). Either way, I'd be very surpassed if yours has not been split at some point.

As already pointed out, the black silicone there that has been used is a bit messily applied, and possibly that suggests that it wasn't applied correctly around the inside edge of the bolt holes, which is allowing the fluid to seep through by the bolt heads.

The only 'real' fix would be to split the gearbox, and re-seal it. A rather major job for, what I presume is, a small leak! You could try various other bodges to try and seal the bolt head, either with a sealant under the bolt head or a sealing washer.

I doubt it's going to do anything other than weep a little, personally I'd not loose too much sleep over it!

Thanks very much for the response and input. I didn’t know it was sealant and thought it was indeed a gasket. So that’s good to know for future lessons. I think I will try sealing the bolts better and see how that goes first.

Thanks very much again for your help

 

[bugsymike]

Just curious, would I be right in saying when the original 1957 Fiat 500 was introduced it would have been a thin paper gasket as in those days sealant alone was not as effective as currently the case, indeed it wasn't until I worked for a Mazda dealership around 1975 that I came across gearboxes using sealant and a face fit oil tight seal with success.

 

[the hobbler]

Thanks very much for the response and input. I didn’t know it was sealant and thought it was indeed a gasket. So that’s good to know for future lessons. I think I will try sealing the bolts better and see how that goes first.

Thanks very much again for your help

The factory didn't use either a gasket OR sealant at the bell-housing/gearbox joint,which is why they used to say that if the the bell-housing had to be replaced, one should also replace the 'gear-box' housing----but I sincerely doubt whether anybody actually did! When replacing a bell-housing, I always use a modern silicon 'goo' CAREFULLY spread on the 2 surfaces so that (a) it doesn't leak either into or out of the gearbox and (b) carefully spread around the bolt holes so, as 'Goldenrust' mentioned, no oil can leak up the thread of the bolt. The only sure way of curing the leak is to remove the gearbox and engine and have the bell-housing removed/refitted. For such a small leak, I wouldn't have thought that it warrants the cost of the rectificarion. Only 5 miles in 4 months?---may I suggest that you get it onto the road and enjoy the pleasure of driving a Cinquecento. I sometimes struggle to stay under the 3,000 miles p.a. that my insurance stipulates!

 

[DDW1982]

The factory didn't use either a gasket OR sealant at the bell-housing/gearbox joint,which is why they used to say that if the the bell-housing had to be replaced, one should also replace the 'gear-box' housing----but I sincerely doubt whether anybody actually did! When replacing a bell-housing, I always use a modern silicon 'goo' CAREFULLY spread on the 2 surfaces so that (a) it doesn't leak either into or out of the gearbox and (b) carefully spread around the bolt holes so, as 'Goldenrust' mentioned, no oil can leak up the thread of the bolt. The only sure way of curing the leak is to remove the gearbox and engine and have the bell-housing removed/refitted. For such a small leak, I wouldn't have thought that it warrants the cost of the rectificarion. Only 5 miles in 4 months?---may I suggest that you get it onto the road and enjoy the pleasure of driving a Cinquecento. I sometimes struggle to stay under the 3,000 miles p.a. that my insurance stipulates!

Thanks very much for the advice and input. Those extremities will be a last resort if the other smaller/simpler options fail.

The reason I don’t “drive” it is because it’s a concourse show car. And is used for that purpose only

 

[DDW1982]

Just as an idea

 

[Toshi 975]

Just out of interest did you remove the flywheel cover plate for the first picture in the thread or is it missing?

 

[DDW1982]

Just out of interest did you remove the flywheel cover plate for the first picture in the thread or is it missing?

I took it off to investigate the leak

 

[Bleeding Knuckles]

Hi DDW, as far as I can tell the lower three bolts do not access the oil in the diff area, the joint between the bell housing and gearbox is only sealant no gasket needed. Are you sure the oil is coming from this area alone???? In your pic the lower gearbox structure looks dirty (oil?) I would council you to clean the area well and run the car until warmed up. There is (can be) a problem with the drive shaft rubber seals not containing the gearbox oil leaking from the lower edge of the clamp on the bearing retainer. Driving the car will make any leak flow towards the flywheel and a small amount of oil will spread all over the place, clean it and test drive!!!!
Ian.

 

[DDW1982]

Hi DDW, as far as I can tell the lower three bolts do not access the oil in the diff area, the joint between the bell housing and gearbox is only sealant no gasket needed. Are you sure the oil is coming from this area alone???? In your pic the lower gearbox structure looks dirty (oil?) I would council you to clean the area well and run the car until warmed up. There is (can be) a problem with the drive shaft rubber seals not containing the gearbox oil leaking from the lower edge of the clamp on the bearing retainer. Driving the car will make any leak flow towards the flywheel and a small amount of oil will spread all over the place, clean it and test drive!!!!
Ian.

Hi Ian
Thanks for your thoughts mate.

I got underneath it and cleaned it all up and left it parked (without the movement potentially spreading the oil across the flywheel etc). Day later the bolts only were wet. Absolutely nowhere else

 

[the hobbler]

Thanks very much for the advice and input. Those extremities will be a last resort if the other smaller/simpler options fail.

The reason I don’t “drive” it is because it’s a concourse show car. And is used for that purpose only

At the risk of sounding rude----how sad! The Cinquecento was designed to be USED!

 

[Goldnrust]

That’s not really very fair is it.

Close mindedness in small communities of enthusiasts doesn’t help anyone.

If the challenge of competing in concourse competitions is what gives @DDW1982 the most joy from his 500, then that’s all that matters.

Much as others of us will modify our cars and not expect to be criticised by people who believe we are ‘ruining’ our cars.

 

[bugsymike]

Your car, your choice.

 

[the hobbler]

Your car, your choice.

I completely agree with both 'Goldenrust' and 'bugsymike' ---how one wishes to use their car is entirely upto them, as is the way that they wish to 'modify' them. I am just of the opinion that 'Classic'cars should be used--a well used piece of machinery usually gives less trouble than a rarely used one. In the wise words of Jay Leno "classic cars should gather memories, not dust".

 

[smart51]

There is a whole spectrum of classic car enthusiasts

Showmen - the car must be faultless and polished even in places you can't see
Rivet Counters - the car must remain exactly as it was on the day it left the factory
Conservators - the car must keep all its original parts, even if they are broken and irreparable
Authenticators - the car can be modified, but only with parts that are "authentic"
Modernisers - the car should have all the character replaced with big alloys and underglow lights
Sleepers - the car should look original on the outside but sportscar innards grafted on to it
Ratters - the car is too old to bother with maintenance, and should be allowed to rot while just about keeping it running

 

[bugsymike]

I always enjoy videos of J2 Allards and Mk 9 Jags being thrown around a race track, lots of lean, loud exhausts and tyres screaming etc. So unlike F1 these days. Having said that going to a car show and seeing beautiful examples of cars I used to own as a teenager when they were just old bangers for £20 or so always makes me wish I had had access to a big barn at the time, until I realise that even if storage was 50pence per week I would still be out of pocket.

 

[fiat500]

That’s not really very fair is it.

Close mindedness in small communities of enthusiasts doesn’t help anyone.

If the challenge of competing in concourse competitions is what gives @DDW1982 the most joy from his 500, then that’s all that matters.

Much as others of us will modify our cars and not expect to be criticised by people who believe we are ‘ruining’ our cars.

I agree.

But anyone who uses their car only for concours events is choosing to miss out on the main point of owning a classic Fiat 500.....namely the "fun" of anticipating where the next bit of bodywork welding will be needed.

Whatever it is about the little Fiat that gives you a kick, go for it as often as you can; the time comes all too soon when you won't be able to. That was made all too plain to me a couple of years ago when Tony, (who was a stalwart of this forum), died, having hardly driven his immaculately and authentically restored car. Having said that, his great pleasure came from working towards perfection, whilst mine came from turning my Fiat into a leaky pile of rust. But we got on really well because of our common interest in the phenomenon that is the Fiat 500.