Oil Light

[Kent126]

Oil light came on today, so checked oil level, slightly low so topped up slightly so no probs there.

No leaks from under the engine, checked that too.

Oil light is now on permanently, does not go out when revving the engine either.

I'm thinking its the oil pressure sensor that needs replacing, as the car drives fine. Have ordered a new one, and will update how I get on once its fitted. Hopefully its nothing serious, as I dont want to miss Auto Italia.

Anyone else had the same problem?

Tom

[Allan]

Yep seen this before. I am alway suspicious of the actual oil pressure when this happens so be careful. If you can get the oil pressure checked with a mecanical tester it will give you the peace of mind you need to keep driving. I have also seen the person who (not me) who decided that because there was plenty of oil on the dipstick and (initially) no noises there was nothing to worry about and drove until the engine seized.
Someone else was having problems with the two sizes of oil pressure switch sizes. There are as I recall two different sized threads but because all my literature is currently in storage I'm sorry I can't tell you exactly what they are.

[bis13]

m12 and m14 are the two sizes.

[Kent126]

OK PROBLEM APPEARS SOLVED

Started the car today, and the light had gone out after cleaning the connection to the top of the pressure sensor. A lot of gunk and oil, so hopefully that has cured the problem.

With a bit more time tomorrow I shall get the spanners out and thoroughly clean the whole unit. Will replace with a new unit when it arrives as a precauton.

Tom

[dajwid]

Could you just fit a oil pressure gauge?

[Kent126]

I could do, but im a bit of a saddo and purist, and want to keep the car as close to original as possible. 

It had crossed my mind though, and was looking at some period smiths dials.

Tom

[Rusty's Uncle]

For the record the thread size is M12 . Better safe than sorry with the oil pressure as a guy contacted me the other day as his oil light stayed on. Turned out one of the core plugs on the crankshaft had dropped out so instant total loss of oil pressure so beware. Not a problem I had come across before but when I mentioned it to smallcox he was aware of it.
The bit you are talking about is the oil light switch. I just changed a dodgey one on my car. The standard one was fitted to a number of Fiat engines and you could probably pick one up in your local main agent over the counter. A poor contact on the switch would mean that it would not come on rather than stay on when the engine is running.
A sender / sensor would be used when you fit an electric oil pressure gauge  

[Kent126]

Thanks for the info Rusty. I will still get the pressure checked to be on the safe side, replace the switch and see what happens.

Tom

[Darrell]

Don't muck-about with oil pressure.

Mine lacked it, so did tests with a gauge and it was confirmed to be low.

After an exhausting investigation I found a chunk was missing out of the rear main bearing. Possibly due to pinching of the rear bearing during an overheat.

If this had been allowed to continue it would surely have ruined the engine.

[TerryParkin]

Can anyone tell me what psi at what revs is good, or OK, or worrying /
Ta.

[Pete126]

Can anyone tell me what psi at what revs is good, or OK, or worrying /
Ta.

Hi Terry,

According to the 126 600cc fiat manual when the engine is hot 16 to 22 psi @ 850rpm and 35.5 to 42.7 psi @ 3000rpm so the 500 should read similar.

Can't find a specification for the oil pressure switch, but most of them turn the low oil pressure light on @ 10psi and under.

[AlleyNiki]

Don't muck-about with oil pressure.

Mine lacked it, so did tests with a gauge and it was confirmed to be low.

After an exhausting investigation I found a chunk was missing out of the rear main bearing. Possibly due to pinching of the rear bearing during an overheat.

If this had been allowed to continue it would surely have ruined the engine.

Hi Darrell,

How does one go about testing the oil pressure with a gauge?

[TerryParkin]

Can anyone tell me what psi at what revs is good, or OK, or worrying /
Ta.

Hi Terry,

According to the 126 600cc fiat manual when the engine is hot 16 to 22 psi @ 850rpm and 35.5 to 42.7 psi @ 3000rpm so the 500 should read similar.

Can't find a specification for the oil pressure switch, but most of them turn the low oil pressure light on @ 10psi and under.

Thanks Pete, co-incidentally my oil light is giving mixed signals. Recently, after 25-30 miles at a steady 55mph the oil light came on, but when I slowed down it went out.  It sounds more like a faulty switch than low oil pressure - unless someone can tell me any different ?
Terry

[Darrell]

I bought an oil pressure switch that had a fitting to go in to the oil light place.

It's worth checking for peace of mind. Mine sits at a steady 40psi

[Allan]

Another point on this. You should always make sure that your oil warning light is on before you start the engine. If the light does not come on then you have a problem with either the switch, wiring or bulb.
Allan