As it is beginning to get warm in southern England, I am beginning to suffer the consequences of a hot running engine. I have read many a post on the subject with a whole host of ideas and suggestions as to how to cure the various problems and have come to the following conclusion.

1) The FIAT 500 is 60 years old this year and made in a time where journeys were a lot shorter than today. Maybe the 500 was only ever intended for short journeys, thus little chance of the engine getting too hot.

2) The 500 & 500L instruction booklet describes how to start the car when very hot (no choke, accelerator fully down). This suggests the engine is known/expected to get hot.

3) It is not a modern vehicle with the latest cooling methods, it is a classic air cooled vehicle which will naturally get hot


In concluding my thoughts, in my case, I will just except the car will get hot, it is normal and there are little things I can do to try and stop engine cut out due to heat.

-- The most effective has been making sure ALL fuel pipe connections are as air tight as possible, replacing jubilee clips for good quality fuel pipe clamps solved 90% of the cut out problems.

-- Utilising the hand throttle has helped. When the engine is so hot it gets to the stage it feels it will cut out when I stop, I apply a bit of hand throttle which prevents a stall.

-- Making shorter, more realistic journeys.

In short, instead of worrying about an over hot car, I accept the car engine will get hot and just enjoy the car as it is.

Stuart.

1969 RHD FIAT 110F (Berlina 500)
Instagram: fiat_500f
A member of the FIAT 500 Owners Club UK.

I agree with your philosophy

I have to mention that I live in Rome, which can get very very hot in the summer (it's already 35 degrees right now) but I never experienced any overheating problems with my 500's, even when I take 'em to the beach and I drive 40 minutes at full throttle... I admit I never go for longer distances, but since I will have to drive 700 kilometers to go to the 500 meeting in Garlenda, I will have an update on that soon enough

Good fluid flow in and out of an engine always helps temperature. Clean air and fuel filters, reducing any other non design restrictions from vents and so on, a proper exhaust without clogged or displaced baffles etc... .

I live in Greece with summer temp up to 38 to 40 degrees, seems that those little cars can handle heat but what you can do to help it a little is to put a 3.5lt aluminum oil sump. It helps a lot and you can see the difference from the oil pressure light.

Stuart SDHXIII this crops up frequently on the Forum, which implies that some of your assumptions may be correct. Although my driving is mainly at the cooler end of the UK, I do a lot of it and for extended periods of up to three hours. The engine has only got really hot on one occasion in 18,000 miles; this was in summer on a very long incline of over two miles when I insisted on using 4th gear when third would have been better.

I think the engine would be expected by design to run hotter than a water-cooled, but this in no way implied that the car was intended to be of inferior ability to any other car. Look at the other common types of air-cooled vehicle, such as the Beetle or it's big brother van or the air-cooled Porsche.

If your car has a standard engine and everything else is as original and properly fitted and adjusted I am sure that current British temperatures should not cause problems.

Hi Stuart,

I have just resurrected a 1969 Fiat 500F after sitting in a shed for almost 10 years. My first drive of any consequence was a few days ago and overheating was one thing that was concerning me, mostly because of the oil smells from 10 years of crap burning off the engine. It didn't help that the thermostat flap has been welded open by a previous "mechanic".

The cylinder head got to about 110 C after a 20 minute run. It felt a lot hotter, probably because of the heat from the exhaust pipes. By comparison the maximum cylinder head temperature on our aeroplane (Yak 52) is 220 C. Air cooled engines run hotter than the water cooled ones we are used to. It is like the sound of tortured gearbox metal when the Mrs drives it..... something to be accepted.

Chris

Well I have decided to add 2p to this "Hot engine" discussion...
Only drove my sort of roadworthy (now not) 500 short distances and yes it does get hot (500N with 650 engine and original gearbox)
However i also have a VW Splitscreen van and the same hot running relates that that..
like most people I tend to drive a modern daily.. pulling about 2500-3000 rpm doing 60-70mph cooling provided by airflow through the radiator, so we are used to these low rpm quiet cars...
Drive an aircooled and you apparently are supposed to keep it revving as the direct cooling to the engine is provided by the engine driven fan and the oil, problem is they are noisy and we tend to change up to keep the revs down..
If anyone wants to run an engine without the fan to see how long it would last or measure the temperature rise that would be interesting...
These aircooled vehicles were daily drivers and work horses and I don't think they broke down every other day perhaps we treat them with kid gloves more than we should...
A question... How many people have the Engine Under tray fitted with the exhaust shield?
I know on my VW that the seal between the engine and the body was important so air was drawn in and blown out rather than recirculated around the engine, and this made a considerable difference, perhaps no so significant on the 500 design as there is no seal...but there must be some airflow design..
I wonder what the air flow path was designed to be on a 500, like most I would think the larger sump would help, and perhaps on a daily driver a smaller dynamo/alternator pulley to spin the fan more at our modern lower rpm driving styles.

Bigvtwin996 said:

How many people have the Engine Under tray fitted with the exhaust shield? .............
there must be some airflow design..
.

Click to expand...

I 100% agree with the thrust of that argument and as I have said before, I think the undertray will have a ram effect to help push heated air out through the engine cover louvres.

Apparently the 900e Fiat van I have has a reputation for overheating....also engine at the rear but water-cooled. It has a selection of undertrays and cowls to direct airflow and if any of these are missing or seriously corroded it leads to problems.

Drive quickly, drive often and keep the kid gloves dirty.

I would also add the following (after spending the day trawling through factory books)....
the similarity with the VW engine is no coincidence...
the VW engine (beetle if my memory serves me right) draws air through the vent below the rear screen and the engine cover and blows the air over the engine/cylinders and exits under the car. The Fiat 500 is similar in design (not sure about the drawing in through the engine cover though) but also blows air on to the underside of the sump, (hence that little bit of metal plate on steel sumps is important). the fitting of the larger alloy sumps would probably outweigh this by the fact there is more oil and the sump sticks out lower in the path of the cooler air flow underneath, but there would also be some air blown onto the side from the existing fan and air outlet for the old sump.
The internal design of the tinware is such that the high pressure air goes over the engine and the internal ducting prevents the air to the carb being pressurised too much.
So the condition and sealing of the trunking to this vent below the screen must also be good and the retaining clips must be tight and not allowing leaks or you will be sucking air from within the engine bay back over the engine rather than fresh cool air from outside...
the same could be said for the heater trunking so that this must not be allowed to leak hot air back upwards into the compartment...
Also the shape of the car is no coincidence either.. note similarity with the VW beetle... (yes various derivatives have a different rear end design.... but we do not know if they have problems...)
As the air passes over the roof and the velocity increases, so it is more easily drawn into the engine through the vent, (that's the VW effect)
at the same time the forward motion of the vehicle causes low pressure immediately behind the car and in theory helping to draw hot air out away from the car when in motion.

The big difference that I am not clear about between the VW and Fiat design is...
on the VW Air is drawn in through this vent and through the engine cover louvres and over the cylinders and exits under the car...
I note that there is no "Scoop" ability of 500s engine under tray so I can't see how it would direct any air upwards...
also the Exhaust tin also serves to partly separate the upper and lower part of the engine
and I believe the 126 under tray has some louvres too pointing towards the rear thus allowing air out not in (unless going backwards ).....
and if all the hot air is intended to exit through those little louvres on the engine cover... their area is not that great...
So perhaps the design is such that the under tray and exhaust plate are to channel the hot air under the car or stop some of the hot air from the sump being pushed back into the engine bay so as per the VW is it sucked away by the air flowing under the car aided by the low pressure behind...
Air cooled engines tend to be built using components that are more tolerant of higher temperatures...
to add some facts...
in all combustion engines about 40-50% of the heat exits through the exhaust and about 7.5-10% is dissipated through the oil...
In air cooled engines about 10-15% is dissipated through the metal fins of the engine.. so 25% goes somewhere else.. I presume through radiation from the rest of the engine block/sump/gearbox etc so the importance of all these major components can be seen in the cooling of an aircooled engine.

So my conclusion would be that hot air is meant to exit through the louvres in the engine cover and under the car, but without the tin wear in place there would be a lot of recirculation in place....

Also note the tinware internal design is also different (thermostat is in a different position)and the Sumps also had a sort of channel pressing in the bases on N's compared to later engines and the whole arrangement is very different for the US spec cars. so lessons have been learnt...

i had a horrid experience with highly tuned - newly rebuilt Porsche 911 3.2l air cooled engine.
I hadn't finished running it in when an invitation from a friend to a popular concert on Brighton beach had me stranded in stationary traffic for 4 hours.
Engine got hotter and hotter - smoking hot....
Air cooled - don't like low revs......

Solution - drive it like you stole it.....!

I'll start this reply by stating that I know nothing whatsoever about the Fiat 500 or it's engine... but I do come from a background in aircooled VWs and 2CVs.

This is a common subject on VW forums ('will my engine cook in the summer heat????')

General rules for a happy aircooled engine are:

Let it rev.

All tinware must be in place.

Keep it clean.


Letting it rev means not labouring the engine, when climbing a hill, drop a gear (or two) and keep the revs high. High revs mean the fan spins faster, which means more air flowing over the engine. Higher revs also mean the exhaust gasses are moving faster, which should help to keep the exhaust temperatures lower, aiding cooling. The flywheel is spinning faster, so it's better able to help the engine make it around to the next 'power' stroke, particularly important on a 2-cylinder engine as you only have half as many...

Or, to look at it the other way, if you stay in 4th up a long hill, the revs drop, the engine is struggling to complete the rotation between 'power' strokes (only one per rotation on a two cylinder), it's motion becomes less of a smooth rotation. Each compression and ignition stroke dump a spike of heat into the head that the slower exhaust gasses (exhaust & compression stroke is the slowest part of the engine's rotation) struggle to carry away. A lower engine speed also means a slower turbine, so the cooling airflow is lessened, just when the engine needs it most. EGT and CHT climb rapidly and you have a hot engine.


'Tinware' is essential for directing the cooling airflow where it's needed most, so it all needs to be there.


Clean means not having 50 years of fluff in the cylinder head cooling fins and having clean oil of the correct grade.



I think half the problem people have is that old cars have less soundproofing. Couple that with the lack of a water jacket to further reduce engine noise and 3000 RPM sounds like the end of the world to our ears. You're probably running the engine 500 or more RPM lower than you think you are.

A rev counter is a useful addition, even just a temporary one that can be removed later to keep it original.

When I was driving my VW van, I made use of the gearchange dots that were on the speedo, they show the speed to change up, which is also the speed to change down, if you see what I mean.


Both VW and Citroen engines have been run in the Sahara and other deserts and both can cruise happily all day at motorway speeds (if you accept 56mph as 'motorway'), I don't see why the slightly more modern Fiat engine should be any different.


Other things that are common to all engines also apply, a richer mixture will help with cooler running, as will making sure the timing is spot on. If the ignition timing isn't advancing properly as revs rise, retarded timing will give you an overheating problem, so this needs to be checked.

Italian summers get very hot. Hotter than England.
I live in Australia bloody hot in summer, generally I don't drive it around on days that are hovering over 30 but what I do during the summer or if I go on a longer than usual trip add another half litre of oil.
That extra bit aids the cooling process.

I have today been out on my first run in my restored 500 and this was worrying me as here in Spain the temp is currently 35-38 °. I kept the revs up and although i covered about 6/7 kilometres only she ran well and on getting back home the engine was quite hot compared to a modern watercooled engine. We'll see how she copes.

I drove 1600 kilometers (Rome-Monaco-Rome) over the last weekend with 35 degrees and sometimes even more. No overheating problems at all, and I have the stock oil sump