Technical Help! Oil light on 1970 Fiat 500F

[Tommeezoom]

Hi everyone,
New member here with a 1970 500F, I have only just purchased the car and after a short drive (10 mins) the oil light comes on. I have replaced the oil pressure switch and an oil change with Duckhams mineral 10W40, and after the same 10 minute drive the light comes on again. It begins to flicker, and goes off with hard acceleration but eventually after around 15 mins of driving it is on and stays on. Any suggestions to fix this? The engine does not seem hot and no nasty smells. It’s just been restored and is in very good condition. Thanks in advance.

 

[Toshi 975]

Unfortunately nicely painted parts do not necessarily mean that the engine internals are in such good shape. Car looks very nice but what you describe are classic signs of the bottom end (ie crankshaft & bearings) showing signs of wear with the loss of oil pressure when warmed up. I had exactly the same problem when I bought a car which the seller assured me was perfect. Unfortunately he had gone to great lengths to hide the problem by fitting the wrong switch and actuall destroying the warning light bulb in the dash. Guy was a magistrate by the way !
If that is the case I am sure that you will be gutted but don't panic yet. With those symptoms it is not a complete breakdown but early signs of advanced wear and on an engine that has not had a catastrophic breakdown whilst there will be some wear on the main bearings it is normally the big ends that start to go first. With my engine I removed a big end bearing by just draining and dropping the sump which can be done in situ, check the size from the big end shells and fit a new set. I got shells from a local motor factor for just over £20. That restored the oil pressure on mine. A full bottom end rebuild means an engine out total rebuild and is expensive.

 

[Tommeezoom]

Brilliant, thank you so much! Do you have any pictures of the work or bits I'd need to check/replace? That would be very helpful.

 

[jackwhoo]

Very pretty .
Buy from a dealer?
If yes go immediately back to dealer and ask them to fix it pronto.

Not from a dealer?
Pay cash?
Find an older mechanic who understands old cars with no computers.

Where are you located?

Cheers
Jack

 

[jackwhoo]

Very important, don't drive it at all till it's fixed.

If you bought from dealer get them to collect it, tell them you stopped immediately the no oil pressure light came on.

 

[jackwhoo]

If you doing big end check yourself.
Follow
1 toshi's advice he knows these engines inside out.

2 ask toshi which manual to buy

3 follow the manual

4 if not sure about anything in manual come back on here and ask

Welcome to fiat forum
A friendly place to be

Jack

 

[jackwhoo]

The hobbler and bleeding knuckles also know these inside out
And others who will now be mad at me for not mentioning their names.

 

[Tommeezoom]

Private sale, it won't be driven anymore until it is sorted but there is no way of knowing it is sorted unless it's driven for 10 mins to know if the light will come on or not so a tricky one.

Thanks for such a warm welcome, I'll keep you all posted with progress.

 

[Tommeezoom]

Located North Norfolk.

 

[jackwhoo]

Its almost certainly not the cause but check the insulation on the wire to the oil switch hasn't rubbed through to the copper wire somewhere . That could cause the oil light to come on if the exposed copper wires touched the body.
Finding that would be like winning the lottery so don't bank on it.

 

[Tommeezoom]

Okay! I'll definitely check that out. However the time for the light to come on is almost exactly the same each drive which may suggest something mechanical? I'd rather like to win the lottery this time.

 

[Toshi 975]

I do have to say that the car looks absolutely fabulous , so would not have been cheap I guess. Difficult to imagine that someone would go to that amount of trouble with a worn engine unless the problem emerged after the restoration and the owner decided to unload it. Even with a private sale you may be able to negotiate some sort of compensation if the seller has any conscience. Depending upon who does the work to fix it the parts for a bottom end rebuild would be about £250. That is new main and big end bearings, crank regrind, gaskets, oil etc.
Forgot to mention get rid of that dangerous plastic fuel filter unless you want the car to go up in smoke, search the forum on that one. Also definitely clean out the centrifugal oil filter, may turn up some evidence. For instance I know of a guy who purchased a big 5 figure sum special 500 that had never been run. Turned out to have zero oil pressure. The builder had sand blasted the engine casing and left sand particles inside that wrecked the engine when the oil washed it around the engine. I suffered the same fate with a rocker cover that went for powder coating and sand was hidden behind the struts inside the cover wrecking my rebuilt engine.

 

[Tommeezoom]

Thank you, I'll be sure to replace the fuel filter! Do you have any pictures when the sump is removed to show me what kind of wear I should be looking for?

 

[Toshi 975]

Thank you, I'll be sure to replace the fuel filter! Do you have any pictures when the sump is removed to show me what kind of wear I should be looking for?

Don't replace the fuel filter, get rid of it. If you get major overheating in the engine compartment which can happen for a couple of reasons that plastic is a fire bomb waiting to blow. Plus you have a filter in the fuel tank, the pump and the carb so the plastic one is the 4th one in a short fuel line but for some reason people seem obsessed with fitting them and in the worst position possible. You will need a new length of suitable fuel line.
Will it be you working on the engine ? It is always useful to know a little about a persons technical abilities & knowledge when offering advice. As for wear you are talking about a couple of thou with the symptoms you describe so most likely nothing is going to stand out. With bad wear you can get roughening of the bearing surface on the shells and scoring & ovality of the crankshaft journals. Fiat 500 Haynes manual is a must have, pretty comprehensive and easy to follow. Also worth getting an original owners handbook if you can pick one up. They actually tell you about your car, driving it and how to get the best. Often owners get these cars and never work out how to use the heater or realise that they have a hand throttle.

 

[fiat500]

If you go ahead with what Dave Toshi 975 wisely and respectfully advises I think it might also be worth checking that the connection between the oil pickup tube and the base of the block is tight. There is a thick, rubber washer between the two parts and it's something that doesn't come in an engine rebuild kit. If that union failed or had leakage the oil pump might suck in some air and fail to give full pressure. Whilst you're there you will also easily see if the fine, perforated "gauze" on the base of this tube is in any way blocked by debris which would obviously affect the uplift of oil to the pump.

 

[the hobbler]

If the crank and bearings all measure up OK, and there is no damage to those parts, check the oil-pump. As I have mentioned before when people have had an oil-pressure problem. You MUST match like for like vis-a-vie the oil-pump and the timing-chain cover. The 126 oil-pump is deeper than the 500 pump, so if a 126 pumphas been fitted toa 500 timing-chain cover, this can bringthe oil-pressure relief-valve into operation too early when the engine gets hot. A 126 timing-chain cover can be fitted to the engine, but the pumps MUST match the covers.

 

[F123C]

Hi Tommeezoom,

If you click on the 'Downloads' section in the blue band at the top of this page, then click on 500 (Classic), you can download, for free, both a copy of the Owner's Handbook and a copy of the official Fiat Workshop Manual.

Al.

 

[Tommeezoom]

Hi there,

Thank you for everyone's help so far.

I bought the car with the sump looking like this (dent), would this be a cause of pressure issues?

 

[Toshi 975]

Hi there,

Thank you for everyone's help so far.

I bought the car with the sump looking like this (dent), would this be a cause of pressure issues?

Extremely unlikely as the corners of the sump are not near the oil pick up. It is a rare thing these days to find a used sump that has not been dented to some degree.