Club126UK
Fiat 126 Chat => Fiat 126 Mechanical Problem Solving => Topic started by: Kent126 on April 25, 2011, 08:11:30 PM
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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
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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.
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m12 and m14 are the two sizes.
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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
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Could you just fit a oil pressure gauge?
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I could do, but im a bit of a saddo and purist, and want to keep the car as close to original as possible. :D
It had crossed my mind though, and was looking at some period smiths dials.
Tom
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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 :)
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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
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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.
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Can anyone tell me what psi at what revs is good, or OK, or worrying /
Ta.
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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.
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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?
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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
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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
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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
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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
My oil light had not been coming on for some time. I recently found out that the problem was in the oil pressure sensor itself. The little diaphragm whatsit inside seems to be worn out - earthing the wire onto the engine causes the light to come on, but no light comes on when in contact with the sensor. Taking the sensor out and tapping it a bit caused it to start working again but it's intermittent. The light goes out on starting the engine, but does not go back on again when the engine stops. I think the diaphragm is stuck...
I'd really like an oil pressure gauge as one of the instruments. Suggestions anybody? :)
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Well my oil light goes out as it should, when starting but then comes on for a bit after having driven for a while. Sometimes it goes out if I rev the engine, and sometimes it doesn't.
With a loud knocking coming from the fan, which is possibly broken, I could be overheating.
Would also appear now that I have a minor oil leak from underneath somewhere. Will investigate tomorrow.
Tom
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Tom your problem may well be a crankshaft oil gallery plug which has moved and is allowing some of your oil pressure to leak out.
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Tom your problem may well be a crankshaft oil gallery plug which has moved and is allowing some of your oil pressure to leak out.
oh god, sounds griefy......
Tom
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Instead of starting a new thread figured I would continue this 1 , my oil light has started coming on recenetly at idle or very low revs on take off , once moving its fine doesnt come on , my idle is quite low thanks to tuning perfection but it never used to do it , oil level is fine.
Faulty switch or worse ?
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my idle is quite low thanks to tuning perfection but it never used to do it , oil level is fine.
Faulty switch or worse ?
WARNING Never run any engine under the manufacturers specific RPM on IDLE.
oil pump circulation systems are designed to produce around 20psi at 850rpm (HOT) If you adjust the idle lower than spec" the oil pressure reduces and you run the risk of wearing/stripping the bearings as the crank and big ends are not floating on a film of oil,
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Probably gonna be off the road for a few weeks, as I will be moving house very shortly (again). Finally bought my own house with garden (and plenty of tinkering space!!!!! :P)
Once I have moved and got my car into its new mini garage, I will properly strip it down and get to the root of the problem, along with all the other little jobs that need doing.
;D
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How does 1 determine the rpm without a tacho out of interest ?
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I bought a little rpm gauge that looks a bit like a timing light.
It 'fires black magic' at a sticker one places on the rotating item and gives a read-out of the RPM.
The sticker is that reflective tape, I'll dig it out and write the proper name down if no wise-ass doesn't reply with the full details.
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Unfortunately the only way to check the idle is with a tacho, or with garage equipment, I use a Gunson autoranger meter which does RPM, Dwell and few other Diagnostics, There are some professional timing lights that have a tacho built in but are quite expensive. I also switch the headlights on when setting the idle.
When or if the oil light comes on switch all the electrics on and adjust the carburettor idle adjustment screw until the light goes out and it shouldn't be too far off.
If you have a friendly Garage or Motorcycle shop they should be able to set the idle in a couple of minutes, Once set it will give you an idea with the engine note where it should be in case you have to adjust it in the future.
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Unfortunately Pete don't know about these :P
http://cgi.ebay.co.uk/DIGITAL-RED-LASER-TACHOMETER-NO-CONTACT-RPM-TEST-COUNT-/310314923044?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item484035f424
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That looks good value :thumbup
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Soo my problem persists !
Topped the oil up , light still on at idle.
Wound the idle up , went off for a bit till it got warm then light comes on at idle.
Dropped the oil and filled with new oil , swapped the oil sensor as it had been under pressure from the collapsed flap of the thermostat and was loose , light still no ....
It seems to be slowly getting worse , what exactly should I be looking for next ?
Light does go out as soon as the revs come on but IMO the idle would have to be way to high to stop light coming on now considering its only just started doing it after many years.
Bare in mind this is my spare motor and the refurbished 1 will be swapped out eventually but rather fix this issue if its external.
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i used to get this problem when the engine was hot and at tick-over the the oil light would flicker. i changed the ignition for electronic and the problem went away, so assumed it was running too hot! check your plugs and timing
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Light is on from the moment car is started , goes out when first revved to take off.
Have had elcetronic ignition for a few years now.
Timing is perfect and plugs are new.
Im thinking the bearings are flooged out and oil pressure is suffering.
Guess I will find out when the engines removed and stripped down.
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Wise decision there, doesn't take a whole lot to check the bearngs
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Anybody got any other suggestions on what may be causing it ?
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The usual cause for low oil pressure is worn bearings the only other things i have come across is a weak or broken oil pressure relief valve spring, or the oil filter could be clogged.
I had the same problem a few years ago when i stripped the engine down and checked the bearings this is what i found (see picture) as can be seen the rear bearing has no white metal on, its just worn away and the big end bearings were no better, The engine still drove O.K. and to be honest was not over noisy but that maybe because they are a noisy unit anyway, Check the oil filter first then work your way down to the bottom end.
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Thanks mate , my new motor is nearly complete and ready to swap back , once the current motor is out I will strip it down and inevitably find out whats causing it but it wont be going back in so no way to tell if I find the fault really unless its obvious.
The oil filter is only gravitational isnt it ? It doesnt have flow rate so can that cause low oil pressure ?
If Im honest this engine has NOT been looked after , it generally only gets oil topped up once its to low and light comes on , not the best I know but its not been a priority haha.
The new motor might get a little more respect :)
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Dropped the sump tonight and theres quite a few bits of copper flakes in there , oil pickup wasnt blocked , pistons and end caps have alot of play from side to side , is that normal ?
Flushed the pickup out and going to put some fresh oil in see what happens but I think you are on the money , 1 of the crank case bearings is gone.
Its getting worse by the day now.
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Hi Kal,
Check the oil filter you will be amazed how much crap is in there if its never been cleaned out, It doesn't take long and that could be the cause of the knackered bearings, The oil filter should be cleaned out every service but because they aren't a cartridge type people think they haven't got one,
Here's a link http://club126uk.co.uk/index.php?pid=6 of what i found when i cleaned out mine, although its a water-cooled the filter is the same design as the air-cooled, the oil pump, pumps oil under pressure into the centrifugal filter, all the debris in the oil is spun to the outer edges of the filter body and then deposits the debris on the outer edge which gradually builds up into the centre of the filter, because the diameter gets smaller this allows any dirt/dust/grit into the oil system because it can't do its job properly, It will wear the bearings and can reduce oil pressure if its blocked up, the system is a full flow filter, it flows under pressure through the hollow crank to the bearings and valve train. so as you can imagine its very important that it is cleaned at service intervals :thumbup
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With the oil filter link put up by Pete126, our Nikis don't have the oil thrower shown in the 5th picture. It confused the cr@p out of me for a while there.
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i think you need to look again because you must have the same type this applies to both water cooled and air cooled models.
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Check the main bearings.
It's such an easy job on a 126, engine comes out easy and most likely is the rear one so whip the flywheel off.
You'll regret it is you knacker that engine as 126's always need spares :$ Especially if used alot 8)
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i think you need to look again because you must have the same type this applies to both water cooled and air cooled models.
No oil throwers in my 3 air cooled motors.
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Ditto, no oil throwers in both of my air cooled motors.
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What was the outcome here? My car seems to be having this issue now. Hoping it's the sensor but have a feeling it isn't :(