Some 3000 km's ago my aged bike (80.000 km's) needed a water pump replacement.
Accidentally, I unscrewed the oil relief valve and just mounted it back.
I finished the job and used the same engine oil (some 2-3 thousand km's of usage).
Next day while idling AND warm, light was flickering.
I didn't give much attention but recently I decide to check if this can be something serious.
First, I cleaned very well the oil relief valve - ball, spring and housing.
Then, I strecthed the spring.
Then, I inserted 3mm's of washers.
Then I changed the oil pressure switch. No luck.
I decided to measure pressure and it is easily more than 3 bars and when I throttle a bit it goes up to 5 bars.
Then I decided to check if the idle rpm's can be low.
Cmon tool shows 1900 rpm's (vs 2100 of my other bike). Don't know if this plays any role...
However, I turned a bit the idle screw to increase the idle rpm's and honestly I can't see any increase; still stuck around 1900 rpm's.
Engine tuning with Cmon didn't affect the idle rpm's.
Next step is to change oil and filter (filter is easy like a piece of cake to change - sarcastically speaking)
BTW all these 3000 km's period the light is flickering while idling AND warm (weather temp plays a role too)
Can you make any logic from all these?
Hi, according to the bmw c1 repair manual...the oil pressure at idle and warm engine should be around 0,5 bar and at max throttle around 3 bars.
If I remember correctly, the sensor is activated (warning lights goes on) when pressure is higher than 3 bars.
How did you measure the pressure? Is your new sensor marked with 3 bars?
Sorry, I got it completely wrong...it should be marked 0.35 bar...i.e light up when pressure is bellow this value....
Is your oil pressure switch from BMW? I tried a non-BMW one which was not the right spec and it resulted in a flickering oil light at idle. I’m sure non-BMW ones to the right spec are available, but make sure you check, as others have suggested here.
No it's a Bosch one.
Weirdest of all that this happened after I replaced oil and also unscrewed - screwed back the oil relief valve.
Most probable scenario what Variobob says that the oil filter should be replaced too.
The flickering light at idle is not a problem for me unless it can bring some other issues (which honestly I haven't understoood after studying all international C1 forums if it IS a problem a flickering oil pressure light while idling with warm engine).
I just renewed oil with fresh castrol 10w40... If it continues I will install new oil filter.
Is the oil synthetic? Sometimes this results in a flickering oil light in an older engine. The synthetic gets a bit thinner than semi synthetic when it has warmed up.
Also check the ball in the pressure relief valve is not pitted or damaged, also look at its seat when you have it out, a small particle there could cause a problem.
oil is semisynthetic.
Flickering light means intermittent low oil pressure.
Surely can be harmful in some long term way but only a person that designs and tests engines can state with some credibility how much it affects the wear of the engine bearings.
Some forums say that several engines are designed to work ok with low oil pressure while idling but forums are only forums.
I have driven some 3000 km's with these situation and possibly some undesirable and potentially dreadful wear many have taken place during these traffic light stops and my biggest mistake was that I didn't idle a but higher to prevent the low oil pressure.
Now I am determined to fix it, today I will change oil filter.
Incidentally I had the same thought today morning because I forgot to mention that I have all this time some immaterial but still existent oil leakage from the hole.
Which means that very rarely I top up a little with oil.
But also means that one of the seals is not well put and or greased while assembling the water pump and possibly the tiny leakage drops down a bit the oil pressure.
If I remember correctly, the BMW part has a tapered thread that does not leak but needs *very* careful tightening, whereas aftermarket parts have a normal straight thread, are a bit more torque-tolerant, but need PTFE tape around the threads to stop them leaking.
Changed oil filter and flickering at very warm idle continues.
Time to try thicker oil like 15w40 or 20w50.
But I suspect the whole issue is related to a bit uneven and low idling. But I can't fix that.
After pouring 20w50 oil the oil light stopped flickering at warm idle.
Now I try to understand if I just hide the problem or the engine is OK.
My only source of comfort comes from the fact that I read more than 5 bar pressure with even a little throttle (measurement with engine compression tester fitted into the oil pressure switch hole).
The idle rpm's are a bit fluctuating, I will swap VDO controller to check.
This issue is still going on, even with 20w50 the oil light flickers and at times turns on at warm idle.
I have to keep a little throttle at traffic lights to maintain the light off.
I today changed water pump (some oil was leaking through the seal) but the problem persists.
All this happened after I changed the water pump some 3000 kms ago.
I would wish to have some higher rpm at idle but is this possible???
A car mechanic today told me that this can be related to the fact that the radiator fan never works and the oil becomes very thin after long driving. Tomorrow will check with the cmon tool but only problem is that the cmon tool disables ABS while connected.
Most probably the issue was a result of an aftermarket oil pressure switch (tried a second one with the same effect) along with somewhat lower idle.
The OEM switch doesn't flicker.
Well done to Alunt for spotting this was the likely source of the issue within 24 hours of your original posting.
Yes congrats to him.
Only thing that didn't make any meaning is that the non-OEM oil pressure switch was there long time ago without any symptom of flickering.
The problem started after replacing the water pump (replaced oil without changing filter) where by accident I removed and put back the oil relief valve.
Some of the latter where the tipping points apparently behind the flickering happening thereafter...
After some long time and long trips with no issue, problem came back.
Will check spring and valve
Will need to buy some automatic gun too and shoot it
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