Used the 500 at the weekend as the sun was out and the roof folded back. I had a 4ft sheet of wood to move and some large bags of rubbish to take to the tip and a large gas cylinder to get refilled. Yes....it all went in.

The problems started on the way back. Each time I stopped and had to restart the engine it wouldn't start without several minutes cranking with my foot hard on the throttle. I'm guessing fuel evaporation as the engine bay was very hot. I have the 28imb carby and generator, and the two (unshielded) fuel pipes fun above the throttle linkage/below the inlet pipe. Is there a better/correct routing or do I go for shielding?

I alos noticed that the ingnition leads had dropped onto the rocker cover and the black shielding was melting. The two brackets/grommets don't seem able to keep the leads in mid air (they get hot and flop), so I may have to build a support/bridge.

Most concerning was the oil pressure light which came on unless the engine was revved. Oil is 20W50 mineral, so should be thick enough and is upto the full mark on the dipstick. My guess is the oil pump is a worn and outside tolerance or the pickup has a leak somewhere, but before I go into spanner mode, is there any collective wisdom?

The engine bay does get very hot - i'm thinking of making up some standoffs to hold the lid open by a few inches - anyone tried this and does it make any difference? We had a thread about exhaust wrap - I'm still thinking these used to run in Italy, which is a warm country, so I must be missing something on all of the above.

These annoyances are limiting my use of the 500 as I don't trust it - need to get them resolved.

Cheers in advance.

John

Hmm I had similar problems today John, the first time I have driven the 500 on a really hot day for years. It's about 26c today here and once I was moving it was great to begin with but after a short while I could feel the engine start to miss the odd beat. I only went a few miles as I was concerned if something else was causing the problem. I got home okay, it wasn't that bad but it definitely felt like fuel starvation.

Once the engine was turned off, I tried to restart it but after 30 seconds or so gave up. With the engine not running, looking on the in-line filter by the carb I could see fuel bubbling through which backs up the idea of fuel starvation.

I left it 30mins or so and it started first time and was running really smoothly.
I think one mistake I made was I had the car idling over for about 15 - 20 mins before I set off, so it was not getting and air flow over it to assist and was all ready suffering before I set off.

I sort of remember in my dim and distant past when I last used the car that it really didn't like really hot days. I am not sure if this is just a quirk of the car with it being air cooled or there is something that can be done to improve the situation. I guess all the Aussies on the forum would be much more used to running in really hot conditions.

Oh and I am running with exhaust wrap.

Tony

All my old Italian friends always remind me that the 500 does not like hot days and it has been rather warm up by you recently.

Luxe said:

All my old Italian friends always remind me that the 500 does not like hot days and it has been rather warm up by you recently.

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True it has been warmer than normal up here. I don't think me leaving the car idling for 20 mins did me any favours though.

I will double check all the obvious bits tomorrow. I forgot to look if the thermostat flap was opening on mine.

John I wouldn't prop the engine lid open at the top because you will potentially make it worse, the hot air will flow from the engine bay straight into the air intake grill above. If you notice on some Abarths they prop the engine lid open from the bottom for this very reason.

Tony

It seem strange they suffer from hot weather...
I remember going to the beach in middle August in Rome few years back with my friends, the roof down and the temp was 33/35C!!!
Cant remember my grandad 500D ever suffer from hot weather in sunny Livorno during the summer months...

I'm sure the 500 was designed to take into account the fact that temperatures in many of the regions it would be operated in would regularly be over 25*C. I remember some discussion in my other car club regarding the higher volatility of modern fuel making it more likely to develop a gaseous lock in the fuel line.

Evening Konrod;
To answer 3 of your queries:-
(1)---Fiat advise in the workshop manual (a pukka, original, beige Fiat publication) that the oil light can flicker when the engine is HOT idling, as long as the light goes out as soon as the engine is revved.
(2)---MBG recommended that I use 10/60 oil in the '126' engine in my 500
(3)---The easiest way to prop open the engine cover is to fit a pair of the short (about 6in) bottom lid supports. They fit onto, and between, the pivot pins on the bottom of the engine lid and the pivot tubes on the rear cross-member. The original engine cover release handle can be retained which give the lid a triangulated support.
If you haven't done it already, I would suggest that a 3.5 litre alloy oil sump is fitted--not only does this stiffen up the crank-case, but the extra oil helps keep the engine cool.

fiat500 said:

I'm sure the 500 was designed to take into account the fact that temperatures in many of the regions it would be operated in would regularly be over 25*C. I remember some discussion in my other car club regarding the higher volatility of modern fuel making it more likely to develop a gaseous lock in the fuel line.

Click to expand...

I read somewhere that there is a Summer and a Winter grade of fuel , maybe OP is using old (Winter grade) fuel in Summer?

Al.

Leaving aside the issue of heatsoak causing percolation/evaporation of the fuel which could certainly be the problem, could the carb. be flooding the engine after shut-off due to a worn carb. float valve (needle and seat), also due to amount of engine turning to get it to restart, could the fuel pump spring be weak or internal valves leaking?

Thanks for the input guys, it really is appreciated. I'm sure it was fuel starvation so I think I'll have a fiddle with the routing and shielding of the fuel lines to start with.

I'm also sure the black cover for the HT lines had melted where it touched the rocker cover so I'll make some mods there (probably a supporting wire between the grommet posts running through the black cover).

I think I'll leave the oil pump alone for now but look at the bigger sump and thicker oil - there hasn't been any problem up until the
weather got warmer and I plan to strip the engine out this winter for an overhaul anyway and tidy up the engine bay.

Cheers

John

I had a further look at my car today to see if I could improve the hot starting issue I discovered yesterday. First port of call was to check the valve clearances and I was surprised that a couple of them had closed up considering they were set not long ago.

Reset them all again and double checked and then double checked again. The other favourite seems to be the mixture screw, I found very little affect from adjusting the screw. Took it out and found the little tip had broken off, so that explains why nothing was happening. Fortunately I had a spare.

Connected up the strobe to check the timing. Started first time adjusted the mixture screw and it was now having an affect, so screwed it all the way and backed it out the recommended 1 and a half turns, then tried a further half turn out and that seemed to be the sweet spot.

Checked the timing and ended up retarding it a touch from 10 BTDC as it seemed smoother and more responsive. Let the car warm up til the thermostat was fully open. Then switch off and try restarting. Restarted straight away. Left it a little longer, the sort of time it would take to fill up and pay so 5 mins or so. Again restarted straight away. As an engine tends to get hotter for a period of time after being switched off, I tried different time periods 10' 15' 20' minutes and again started first time.

So the moral to this long winded post, is set your valve clearances on a cold engine on the hottest day you can and you should be fine.:idea:

Still struggling with this one. Re-ran the fuel pipes around the air filter housing and wrapped them in foil to try and refelct the heat. That seemed to make a difference although it still cranked a lot before starting when hot. I also did the full setup (timing, mixture, idle - the valves were done when I changed the rocker cover)


The test run was a short jaunt to a pub (effective use of time ), perhaps 10 miles. The engine cover handle was too hot to touch, and the ignition leads had sagged onto the rocker cover and melted the black sheath and started on the leads themselves. The oil pressure light was also on when idling.

I have to sort out the engine heat issue as that is the crux of all the problems. It's more than the heat from the headers so I guess I need to look at the thermostat and flap mechanism - one thought that occurs as I write this, we obviously had the cabin heater closed as the weather was warm, but previously we've had it open - a clue there perhaps. I also notice there are no covers where the ignition leads go through the covers and some smoke is coming through the holes when hot.

Can you test the thermostat in an oven i.e see it working? The engine is harder to work on when it's hot (read - I'll get burned) so I'm looking for ways to test it off the car.

Thanks in advance.

John

Excessive heat could be down to weak mixture so dodgy carb or air leaks at base of carb. Timing too advanced but my worst overheating happened when the fan blew. Could it be that for whatever reason the fan is not giving the cooling air flow required? You can test a thermostat with a mug and a kettle of hot water.

Toshi 975 said:

Excessive heat could be down to weak mixture so dodgy carb or air leaks at base of carb. Timing too advanced but my worst overheating happened when the fan blew. Could it be that for whatever reason the fan is not giving the cooling air flow required? You can test a thermostat with a mug and a kettle of hot water.

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Yeah agree with Toshi. It must be something to do with the fan if the engine lid handle is too hot to touch. It could be something as simple as a slipping fan belt??? It sounds far too hot for a simple thermostat failure.

I agree with the above. Also check if the huge air intake pipe is properly connected at both ends and does not have splits in it nor has partially collapsed.

Progress.....of sorts.

First test was the flap. It was open, and when I started the car it remained open, which seems wrong to me. With the engine cold I would expect the flap to be closed.

Removed the thermostat cover and undid retaining nut in the center and you can see what came out. It is like a hard set of bellows, which I can't compress them by hand. The upper part you see in the photo next to the bellows, wasn't attached to the bottom part you can see attached to the rod in the second picture.

So it seems I don't have a working thermostat , and to connect one to the rod I think I'll need to take the compete duct off. I failed - there is obviously at least one fixing I couldn't find. I took off the one by the header and the one that is equivalent of where the earth lead connects at the front - is there an equivalent to the drilled bolt that lets gas out at the back, and anything connecting the two ducts (left and right?). Can't find any diagrams that show the back and ran out of daylight. Of course, I'm assuming it will come off without the engine being removed

I also started the engine with the thermostat cover off and the flap held closed. There is a good breeze coming from the fan, but I wouldn't call it a gale - how strong should the airflow be?

The last picture shows the current state with melted ignition wires - plan was to remove the engine this winter and strip/clean/paint/powdercoat it, so apologies for the lairy condition.

And of course, if the flap was always open, fixing the thermostat won't resolve the overheating problem. Back to square one.

Thanks in advance or any advice.

Cheers

John.

John, there should be a hollow bolt on both sides and I think it is possible to do everything in-situ. However, it looks to me like you may as well remove the engine and dismantle all of the external engine components and methodically check them over.
Removing the engine is not that hard and made easier, in my opinion (take a deep breath) if you take out with the transmission still bolted to it. You can even test run the engine whilst out of the car.
There seems to be an accumulation of oil mist on the inside of the cowl and everything looks very tired.
Unless there is a blockage in the airflow, missing intake pipe or very loose fanbelt or loose or damaged impeller the airflow should be OK.
You will soon see any oil leaks or things that aren't right once the cowling is fully removed.

fiat500 said:

......, it looks to me like you may as well remove the engine and dismantle all of the external engine components and methodically check them over.......

Click to expand...

Thanks for the reply, I've resigned myself to that now. I wanted to run it over the summer and then tidy the engine bay and a few bodywork bubbles this winter without it becoming a full on resto - my wife will have a fruit if I do that again. Looks like the summer fun is over.

So open to ideas on how to remove/renovate the engine/box but making it look like regular maintenance/oil change to the boss I won''t be able to do much until the autumn though, so may just remove the thermostat cover to have a look - if the pushrod seals are leaking it should be visible.

Looks like I bought a pup.......:bang:

John

If it was running okay before, i would be tempted to replace the thermostat mechanism and give it a run. It was obviously overheating, but at least you will be able to check if it runs okay before dismantling it later.
You might even get the rest of the summer out of it.
What's the worst that could happen?

Thinking of more things that could lead to overheating; oil soaked fins on the barrels and head would attract dirt that would impede the transfer of heat and might partially block the flow with dirt. Likewise on the sump which has tubes through which cooling air passes. These passages also get blocked with misuse and heavy handling. There is a small piece of cowl under the engine connecting to the sump which might be missing which directs the air.
That engine must be amazingly hot. The only time I had plug lead damage like that was when they fell on the exhaust.
PS. Will you actually see the pushrod tubes with the thermostat cowling removed?...wrong side.
No such thing as a "pup" with 500s..they're all little teddybears, it's just that they've been loved so much that their stuffing is falling out.