Technical Loose cooling fan?

[GrahamH2]

Each time I look at anything on my newly acquired 500R I seem to find yet another bodge or at lease evidence of a first time mechanic. This time I am replacing the Abarth sump as it is leaking, but that's not the real problem. Whilst under the car the red cooling fan can be seen where it blows onto the sump and in an idle moment I touched the fan and it moved. It will rotate loosely about 40 mm at the edge of the fan but isn't it supposed to be fixed tight on the dynamo shaft? I'm pretty sure it should not rotate even a little bit and to fix it means taking out the engine but before I do this could the experienced 500 mechanic out there confirm I have a problem.

Graham

 

[Toshi 975]

Yes you have a problem but you should be able to fix it with the engine in situ if you can get good safe access under the car. As you can only move the fan 40mm it suggests that the fan has worked loose and worn the shaped mounting hole of the fan which would normally be a close fit on the boss. The boss is driven by a key way and woodruff key set in the Dynamo or alternator shaft. You won’t know until you strip it out which also involves removing the rear fan housing and probably the top fan housing . Bit of a faff but if the fan fails completely the engine will overheat really quickly.

 

[the hobbler]

Yes you have a problem but you should be able to fix it with the engine in situ if you can get good safe access under the car. As you can only move the fan 40mm it suggests that the fan has worked loose and worn the shaped mounting hole of the fan which would normally be a close fit on the boss. The boss is driven by a key way and woodruff key set in the Dynamo or alternator shaft. You won’t know until you strip it out which also involves removing the rear fan housing and probably the top fan housing . Bit of a faff but if the fan fails completely the engine will overheat really quickly.

As Dave (Toshi) has said, it CAN be rectified in-situ, but as you are not sure which part is the faulty one--usually the actual fan elongating, as Toshi mentioned, the shaped part of the fan by the dynamo /alternator shaft. As you are re-sealing the sump as well, it might just be easier to heave the engine out to carry out both jobs. With regard to the sump sealing, I (and a number of other people) now use a silicon sealer rather than a gasket. If you DO use a gasket, use the rubberoid version and not the cork type. When using the silicon sealer, put the sealer just on the outer half of the sump-flange and around the bolt holes. This is to prevent sealer being squeezed into the sump. I use 20mm x 6mm stainless cap-head (allen) screws and the original oblong Fiat washers to secure the sump.

 

[GrahamH2]

As Dave (Toshi) has said, it CAN be rectified in-situ, but as you are not sure which part is the faulty one--usually the actual fan elongating, as Toshi mentioned, the shaped part of the fan by the dynamo /alternator shaft. As you are re-sealing the sump as well, it might just be easier to heave the engine out to carry out both jobs. With regard to the sump sealing, I (and a number of other people) now use a silicon sealer rather than a gasket. If you DO use a gasket, use the rubberoid version and not the cork type. When using the silicon sealer, put the sealer just on the outer half of the sump-flange and around the bolt holes. This is to prevent sealer being squeezed into the sump. I use 20mm x 6mm stainless cap-head (allen) screws and the original oblong Fiat washers to secure the sump.

Thanks for you and Toshi, I guess I did know as soon as I touched the fan and it moved that it was a not good omen. As I said so far everything I have looked at has had some fault, for instance the previous owner (not the ‘restorer’) found that there was no support fitted for the silencer so it broke the elbows connecting to the head, and later I realised the big air inlet tube to the fan was also missing, and I could go on.

The Abarth sump was leaking from a hard plastic gasket and lots and lots of RTV. The fan shroud was pushing on one side of the sump so the holes would not line up, one of the holes in the sump was drilled out of position, and the sump had been held in place with allen capscrews without washers. The screws were tightened until they dug into the aluminium and distorted it so the 7mm holes in the sump flange needed to be drilled out as they had distorted under the pressure. I have a new rubberised gasket and thick washers so I think that should be OK.

When I drove it home (170 miles) it went quite well at first but was running quite roughly at the end. I didn’t want to stop as I was unsure it would start again and as it turned out the engine cover was so tightly stuck I could not have done anything to fix it. Without the big tube I think the cooling must have been somewhat compromised.

But also about 100 miles in I could detect a clicking sound in third gear, then later also in top gear and very close to home it was all the time. A quick check has shown that when the offside rear wheel is spun in neutral there is a clicking noise, (not on the near side wheel) but I’m not sure if it is the same noise. Any ideas where to start to look for it?

So the engine will come out to fix the fan and also I hope I can track down what is making the noise.

Graham

 

[Toshi 975]

If you are removing the engine then I would be inclined to remove all sections of the fan housing as you may find that they need a good clean on the inside where oil and grout deposits can build up, not to mention the odd spanner or spark plug. Those deposits can send some pretty smelly air into the cabin via the heater tube. Let us know what you find with the fan and the mounting. Incidentally I have a pal in the Halifax area who has a few bits and bobs should you need anything, you can message me if you would like more info.

 

[GrahamH2]

I have read that the engine could be removed in 45 minutes, well it took me a bit longer but without any serious problems other than the workshop manuals need a pinch of salt when working on a type R, (the missing link between the Fiat 500 and the 126). I have a small red scissor lift which is a brilliant tool when working on motorbikes and again on the little Fiat, highly recommended.

The fan shrouds came off OK although I lost count of the number of screws and certainly would not recommend doing this with the engine in the car. The problem was now obvious, the M10 nut holding the fan in place was not tight and also the friction washers were non existent so the fan bore is somewhat compromised, (that’s polite for knackered). So a new fan and washers and we will be back in business. But that leads to a couple of thoughts and questions.

There are two prices on the interweb for fans, either about £35 or £95. The expensive fan is touted as better construction and balanced, is it worth the extra cash?

The friction washers look like double sided emery cloth, could they be home made from emery cloth? Or perhaps simply coating the flange intersection with coarse grinding paste?

With my old bikes I have been able to find parts manuals and they are invaluable, certainly as useful

as the workshop manual; but I have yet to come across a Fiat 500 parts book, do they exist and if so where can I find a copy? It is tricky to order parts without part numbers and the parts books show where they should fit. I tend to believe whoever connected the fan did not even know about the friction washers; a parts book could possibly have avoided the whole problem.

 

[the hobbler]

I have read that the engine could be removed in 45 minutes, well it took me a bit longer but without any serious problems other than the workshop manuals need a pinch of salt when working on a type R, (the missing link between the Fiat 500 and the 126). I have a small red scissor lift which is a brilliant tool when working on motorbikes and again on the little Fiat, highly recommended.

The fan shrouds came off OK although I lost count of the number of screws and certainly would not recommend doing this with the engine in the car. The problem was now obvious, the M10 nut holding the fan in place was not tight and also the friction washers were non existent so the fan bore is somewhat compromised, (that’s polite for knackered). So a new fan and washers and we will be back in business. But that leads to a couple of thoughts and questions.

There are two prices on the interweb for fans, either about £35 or £95. The expensive fan is touted as better construction and balanced, is it worth the extra cash?

The friction washers look like double sided emery cloth, could they be home made from emery cloth? Or perhaps simply coating the flange intersection with coarse grinding paste?

With my old bikes I have been able to find parts manuals and they are invaluable, certainly as useful

as the workshop manual; but I have yet to come across a Fiat 500 parts book, do they exist and if so where can I find a copy? It is tricky to order parts without part numbers and the parts books show where they should fit. I tend to believe whoever connected the fan did not even know about the friction washers; a parts book could possibly have avoided the whole problem.

View attachment 437454

I have read that the engine could be removed in 45 minutes, well it took me a bit longer but without any serious problems other than the workshop manuals need a pinch of salt when working on a type R, (the missing link between the Fiat 500 and the 126). I have a small red scissor lift which is a brilliant tool when working on motorbikes and again on the little Fiat, highly recommended.

The fan shrouds came off OK although I lost count of the number of screws and certainly would not recommend doing this with the engine in the car. The problem was now obvious, the M10 nut holding the fan in place was not tight and also the friction washers were non existent so the fan bore is somewhat compromised, (that’s polite for knackered). So a new fan and washers and we will be back in business. But that leads to a couple of thoughts and questions.

There are two prices on the interweb for fans, either about £35 or £95. The expensive fan is touted as better construction and balanced, is it worth the extra cash?

The friction washers look like double sided emery cloth, could they be home made from emery cloth? Or perhaps simply coating the flange intersection with coarse grinding paste?

With my old bikes I have been able to find parts manuals and they are invaluable, certainly as useful

as the workshop manual; but I have yet to come across a Fiat 500 parts book, do they exist and if so where can I find a copy? It is tricky to order parts without part numbers and the parts books show where they should fit. I tend to believe whoever connected the fan did not even know about the friction washers; a parts book could possibly have avoided the whole problem.

View attachment 437454

There is such a thing as a 'Fiat 500 parts book' I have been lucky enough to obtain both a "Catalogo Partico Di Ricambi" (mechanical parts) and a "Catalogo Parti Di Ricambio Carrozzeria" (body parts), Being that both books are in excess of 80 double-sided pages I am not able to copy them out for people, but if anybody wants original part numbers for specific parts I am always ready to try and help. Just contact me direct on--- [email protected].
I like the the little scissor-jack; not having one of those, I made a plate that sits under the sump and has little 'lump' on the underside to locate into the top of my small trolley-jack. I have heard of people being able to take an engine out in very short times---I take about 1-1/2 hors to remove my engine from start to having it on the floor.

 

[GrahamH2]

There is such a thing as a 'Fiat 500 parts book' I have been lucky enough to obtain both a "Catalogo Partico Di Ricambi" (mechanical parts) and a "Catalogo Parti Di Ricambio Carrozzeria" (body parts), Being that both books are in excess of 80 double-sided pages I am not able to copy them out for people, but if anybody wants original part numbers for specific parts I am always ready to try and help. Just contact me direct on--- [email protected].
I like the the little scissor-jack; not having one of those, I made a plate that sits under the sump and has little 'lump' on the underside to locate into the top of my small trolley-jack. I have heard of people being able to take an engine out in very short times---I take about 1-1/2 hors to remove my engine from start to having it on the floor.

Thank you, it just took the correct words to search and I found a parts list, well illustrations at least, at 'http://nuova500.free.fr/tecnica.html'

 

[Toshi 975]

I have read that the engine could be removed in 45 minutes, well it took me a bit longer but without any serious problems other than the workshop manuals need a pinch of salt when working on a type R, (the missing link between the Fiat 500 and the 126). I have a small red scissor lift which is a brilliant tool when working on motorbikes and again on the little Fiat, highly recommended.

The fan shrouds came off OK although I lost count of the number of screws and certainly would not recommend doing this with the engine in the car. The problem was now obvious, the M10 nut holding the fan in place was not tight and also the friction washers were non existent so the fan bore is somewhat compromised, (that’s polite for knackered). So a new fan and washers and we will be back in business. But that leads to a couple of thoughts and questions.

There are two prices on the interweb for fans, either about £35 or £95. The expensive fan is touted as better construction and balanced, is it worth the extra cash?

The friction washers look like double sided emery cloth, could they be home made from emery cloth? Or perhaps simply coating the flange intersection with coarse grinding paste?

With my old bikes I have been able to find parts manuals and they are invaluable, certainly as useful

as the workshop manual; but I have yet to come across a Fiat 500 parts book, do they exist and if so where can I find a copy? It is tricky to order parts without part numbers and the parts books show where they should fit. I tend to believe whoever connected the fan did not even know about the friction washers; a parts book could possibly have avoided the whole problem.

View attachment 437454

Re part numbers whilst they are useful for identifying old stock items that you might turn up pretty much all the suppliers these days have either invented their own stock codes or just go by description but as you say parts books are useful in identifying exactly what you should have.
As for the fan friction pads I have come across the abrasive ones but more frequently they have been a kind of rubber impregnated cloth material.
The standard fans have an odd construction in that the vanes just slot through back and front plates and are then twisted to hold them in place in slots. They are known to fail especially in high mileage engines (as I found out) where everything has worked loose or where corrosion has taken hold.
The more expensive fans generally are standard fans that have been welded for extra security then balanced. The other option you did not mention is the cast alloy fans. I went down a different route by having some standard fans powder coated to give them a bit more structural integrity.

 

[the hobbler]

Re part numbers whilst they are useful for identifying old stock items that you might turn up pretty much all the suppliers these days have either invented their own stock codes or just go by description but as you say parts books are useful in identifying exactly what you should have.
As for the fan friction pads I have come across the abrasive ones but more frequently they have been a kind of rubber impregnated cloth material.
The standard fans have an odd construction in that the vanes just slot through back and front plates and are then twisted to hold them in place in slots. They are known to fail especially in high mileage engines (as I found out) where everything has worked loose or where corrosion has taken hold.
The more expensive fans generally are standard fans that have been welded for extra security then balanced. The other option you did not mention is the cast alloy fans. I went down a different route by having some standard fans powder coated to give them a bit more structural integrity.

I contemplated putting an alloy fan into the '695SS' engine that I am building. However, when I received it, I was not impressed with the quality, so instead 'bit the bullet' and bought a 'welded and balanced' fan. The alloy fan is available if anybody wants it---it had never even been fitted, so it can be had for 1/2 price.
As David ( 'Toshi') has pointed out, the common;y available 'fan friction pads' seem to be a sort of rubber-impregnated cloth; I would obtain a couple and fit them. I think that Mark at 'Motobabmbino' has them for sale---it might also be wise, if he has them, to get a new 'cone-shaped' spacer washer (the one that goes between the fan and the retaining nut)

 

[Bounding Bambino]

I also have a alloy fan. I had it installed for a few runs while i was troubleshooting my carb. I ended up swapping back to a standard fan thinking i was having an overheating issue (i wasnt). but the airflow difference is significant. I really wish i had done some airflow tests before/after. To me, in my opinion, the alloy fan is on the verge of not providing enough cooling for day to day driving (stuck in traffic, low rpm, stop and go). It really didnt have much flow until the engine was really starting to rev. I could see it being used perfectly in a racing application where the engine is typically 4000rpm+ all the time. But i had my suspicions for a road car.

The fan not being a welded type does concern me slightly, as my car does see significant rpm when driving. I will eventually test and see how out of balance a factory fan can be.

 

[the hobbler]

I also have a alloy fan. I had it installed for a few runs while i was troubleshooting my carb. I ended up swapping back to a standard fan thinking i was having an overheating issue (i wasnt). but the airflow difference is significant. I really wish i had done some airflow tests before/after. To me, in my opinion, the alloy fan is on the verge of not providing enough cooling for day to day driving (stuck in traffic, low rpm, stop and go). It really didnt have much flow until the engine was really starting to rev. I could see it being used perfectly in a racing application where the engine is typically 4000rpm+ all the time. But i had my suspicions for a road car.

The fan not being a welded type does concern me slightly, as my car does see significant rpm when driving. I will eventually test and see how out of balance a factory fan can be.

I rather agree with you Jacques---in my opinion also, the alloy fan is maginal for day-to-day running. I have a 'standard' steel fan in my current engine (the one you drove) and have never had a problem with it---and it has been known for me to take the engine to "over 5,800pm" ("only occasionally officer").My '695SS' engine has a"welded-blade and balanced" fan

 

[GrahamH2]

A new fan arrived from Ricambio, welded type, and has been fitted with new washers, woodruff key and nyloc nut. It seems to spin OK and I also did a trial fit of the other half of the shroud so we are moving on. I noticed in the workshop manual a special tool for holding the dynamo shaft whilst working with the fan nut so made one out an odd bit of scrap. The dynamo shaft can now be held in a vice and the nut tightened.