why does the oil warning light come it idle?

[lizard121]

Have noticed when hot and idling in traffic the red dash engine oil light starts to flash. Give some revs and it goes out....do I need to top up my oil??

[E30BeemerLad]

well it would be a good idea to check the level dude

The light coming on is suggestive that you have low oil pressure.

If the levels are OK then you need to check the oil pressure sensor and maybe try another one, if the symptoms remain then you may be looking at needing the oil pump replacing.

Is the tickover rpm normal or has it got an uneven idle where it is almost stalling?

[lizard121]

come 2 mention it yes the idle can get uneven and yes sometimes she tries to stall.....new oil pump then???

[E30BeemerLad]

Check the oil level, but it sounds more like the oil presure problem is more down to the dodgy idle as the revs are dropping so much that the pump can't make proper pressure, which is why the warning light comes on. Sounds like the pump and sensor are doing what they should.

Poor idle can often be due to cracked hoses in the inlet system which lets in unmetered air and confuses the sensors as the engine is getting more air than the systems think it should, so it chucks in a bit more fuel, the engine revs a bit, it kills the fuel and the revs die back down and it nearly stalls, then this cycle is repeated.

I reckon if you cure the poor idle problem this will go away, but I'm certainly no expert.

[StuBeeDoo]

Have noticed when hot and idling in traffic the red dash engine oil light starts to flash. Give some revs and it goes out....do I need to top up my oil??

I can just imagine Barry's reaction to this!!

FWIW, I recently had a similar issue with oil light flickering at idle. Plenty of oil in (I religiously check oil and coolant every few days) and no knocks or rattles. The OPS was a new one from ECP roughly a year ago, and the oil pump was a new BMW one 5 months ago.
A new genuine BMW switch has cured it. Light goes out now as soon as the engine starts.

HTH
Stuart.

[Simon13]

your engine is on limited time!

[B7]

Main bearings will be shot plus no doubt Big ends as well.

You could fit a new oild pump which MAY put the light out on idle but only a matter of time before it's starts glimering again.

[e301988325i]

I've heard that cheap and nasty oil filters can cause enough of a restriction at idle to cause the light to come on.

[Rav335uk]

check your oil , then I would change the OPS first and go from there.
I had the same problem, turned out to be the OPS

[Andyboy]

If it's an M40 (316i and 318i), it could be a weak oil pump - they were known for it.

But do an oil and filter change*, new OPS and make sure it's idling at at least 750/800 rpm. If it's not knocking its tits off under part load, it's probably okay as long as you don't cane it. Pacerpete and I conducted an experiment to see how long an M40 would run without oil. Well, after 20 minutes idling it hadn't seized so we added a gallon of water to the sump. That put the oil light out.....water pressure!
It lasted 10 mins, seized, but then restarted 20 mins later. We gave up at that point.


*Duckhams Q or Castrol High Mileage ftw!

[StuBeeDoo]

Pacerpete and I conducted an experiment to see how long an M40 would run without oil. Well, after 20 minutes idling it hadn't seized so we added a gallon of water to the sump. That put the oil light out.....water pressure!
It lasted 10 mins, seized, but then restarted 20 mins later. We gave up at that point.

Well done, those men! It was only two-thirds of an engine anyway.....

[TouringTash]

Would running a thinner oil keep the lump going for a little longer?
So a car could be used whilst another donk is sourced?

[TouringTash]

your engine is on limited time!

Is that similar to working to rule for an engine?

[StuBeeDoo]

OP.... Have you got to the bottom of this problem yet??

[magpie]

does it growl on first start up ?

[harry_p]

Would running a thinner oil keep the lump going for a little longer?
So a car could be used whilst another donk is sourced?

You'd generally use a thicker oil as it's less likely to get squeezed out of the gaps in the worn shells and will hold more pressure in a worn pump.

[magpie]

does saw dust in gear boxes really work?

[Raj_p]

Have you any oil leaks? what engine you got? Perished oil seals could cause a loss in pressure, if you have an oil cooler, checking the seals, it could be something simple, but yet could be something major

When i first got my Volvo, the oil light started flashing on idle after a few weeks of use.... Dealers said it was the oil pump (£420+vat).... When i checked it over Turned out to be oil seals on the oil cooler (£9+vat) changed them and its all sorted.

[B7]

Have you any oil leaks? what engine you got? Perished oil seals could cause a loss in pressure, if you have an oil cooler, checking the seals, it could be something simple, but yet could be something major

When i first got my Volvo, the oil light started flashing on idle after a few weeks of use.... Dealers said it was the oil pump (£420+vat).... When i checked it over Turned out to be oil seals on the oil cooler (£9+vat) changed them and its all sorted.

All external oils seals do is keep the oil inside the block. An oil leak will have little or effect on actual engine oil pressure. Oil pressure when running is mainly abount the PSI held by the botton end (i.e. big ends and main bearings) created by the oil pump. You could even compression test an engine and get great figures but if it's "run" a shell? It'll have little or no oil pressure.

[capri_rob]

Is it an M20 engine or a 4 pot ?

If its an M20 I doubt its the oil level - if the oil level drops on an M20 engine the "Check" control will pick it up well before it gets to a dangerous level. A flickering oil pressure warning lamp needs checking quick !

I've had this problem on an 8v Golf GTi and a secondhand oil pump fixed it.

If the engine seems to be running OK in all other aspects I would try a new oil pump but make sure you get a decent quality one - town325i had one from ECP a while ago which didn't last 5 minutes

[StuBeeDoo]

does saw dust in gear boxes really work?

Dunno aboot that, but I knew a bloke who bought a mk1 Mexicort then found it had sawdust in the rear axle.

[HairyScreech]

^^ it will work to a certain extent, the wood dust will stop the teeth chattering thus making it sound quiet for a few hundred miles.

[universal]

Have you any oil leaks? what engine you got? Perished oil seals could cause a loss in pressure, if you have an oil cooler, checking the seals, it could be something simple, but yet could be something major

When i first got my Volvo, the oil light started flashing on idle after a few weeks of use.... Dealers said it was the oil pump (£420+vat).... When i checked it over Turned out to be oil seals on the oil cooler (£9+vat) changed them and its all sorted.

All external oils seals do is keep the oil inside the block. An oil leak will have little or effect on actual engine oil pressure. Oil pressure when running is mainly abount the PSI held by the botton end (i.e. big ends and main bearings) created by the oil pump. You could even compression test an engine and get great figures but if it's "run" a shell? It'll have little or no oil pressure.

oil pressure has nothing to do with an engines compression!

[B7]

Have you any oil leaks? what engine you got? Perished oil seals could cause a loss in pressure, if you have an oil cooler, checking the seals, it could be something simple, but yet could be something major

When i first got my Volvo, the oil light started flashing on idle after a few weeks of use.... Dealers said it was the oil pump (£420+vat).... When i checked it over Turned out to be oil seals on the oil cooler (£9+vat) changed them and its all sorted.

All external oils seals do is keep the oil inside the block. An oil leak will have little or effect on actual engine oil pressure. Oil pressure when running is mainly abount the PSI held by the botton end (i.e. big ends and main bearings) created by the oil pump. You could even compression test an engine and get great figures but if it's "run" a shell? It'll have little or no oil pressure.

oil pressure has nothing to do with an engines compression!

Thats what I said

"You could even compression test an engine and get great figures but if it's "run" a shell? It'll have little or no oil pressure"

Meaning, a compression test will also not tell you anything about oil pressure. It'll tell you ring / bore condition.

[universal]

just wondering why a compression test was mentioned when the question was about oil pressure?

[aeberbach]

This will take you a while to read but it's very interesting. I felt fine ignoring the parts store guy when he told me not to buy 0W-40 synthetic for my E30 anyway.

http://www.ferrarichat.com/forum/faq.ph ... s_articles

Assuming it's accurate - if not maybe someone can explain what parts are wrong.

He says pressure is a product of viscosity and flow. I have seen the oil light flicker at idle but only when the car is as hot as it ever gets. Perhaps next change, for an Australian summer, I will use a 0W-50.

[B7]

just wondering why a compression test was mentioned when the question was about oil pressure?

Because it's another misconception

[Morat]

One thing that is no longer important is the ambient temperature. Older automotive owner manuals often recommended one oil for the summer and another for the winter. This is still necessary for air cooled engines but is no longer a consideration in pressurized water cooled engines. These engine blocks are kept at around 212 F all year round. The oil is around the same temperature as well. This allows for a single grade oil all year round. Again, this is not the same as on the track where the coolant temperature is slightly higher and the oil temperature is much higher.

From the article you linked.
I say it is good advice, although the numbers are probably not the same for a BMW as a Ferrari.

[dimebag_from_hell]

I if the oil level drops on an M20 engine the "Check" control will pick it up well before it gets to a dangerous level.

I hope your right, gave mine a few we revs today after washing it, looked up at the obc, seen the oilight on and near shat myself.