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BMW_Mick Brick Rider
Joined: 28 Dec 2008 Posts: 36 Location: Ipswich, Suffolk, UK
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Posted: Fri Mar 16, 2012 12:26 pm Post subject: Oil pressure light flickering.... Sorted. |
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I need some input on this please guys.
I recently had a new sprag clutch, clutch and a major service done on my '93 LT. The oil used for the engine was semi synthetic 10/40.
On checking the oil level I noticed it had used some. no surprises there, she's mainly kept on the sidestand (long story) which means the usual cloud of smoke on starting. She's used about every other day and at the moment only for shortish (i.e. about 5 - 10 miles) trips mainly around town. When I took ;the filler cap off I noticed there was white oil in the cap. After a short bout of panic and acting like a headless chicken, I checked the coolant header/overflow tank. No oil in the water at all. Anyway I topped off the oil and there were no signs I could see of white emulsion in the engine.
Now comes the worrying bit. Yesterday and today the oil pressure warning light has flickered on when at a standstill when the engine is hot from town riding. As the engine gets hotter the light will come on and stay on UNLESS I crack the throttle minutely and increase the tickover by maybe 100 rpm, and which point the light goes out. She hasn't used any coolant at all, the level is the same in the header tank as when it was changed in the service. She DOES seem to be running hotter then before the service though.
So the question is, is the oil that was used the wrong sort and am I right in thinking that the water in the oil is likely to be from only doing short trips (I had the same happen many years ago on a non liquid cooled bike). And is the oil pressure light flicker a result of the oil being too thin or contaminated?
I should point out that the performance and fuel consumption are completely normal and there are no unusual sounds from the engine or drops from the oil/water pump (had that happen on a K100RS so I know what to look for).
Thanks in advance. _________________ '93 K1100LTSE, ABS1 in Black 'Connie'
Last edited by BMW_Mick on Sun Mar 25, 2012 11:35 am; edited 1 time in total |
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Inge K. Flying Brick Rider
Joined: 30 Apr 2011 Posts: 458 Location: Norway
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Posted: Fri Mar 16, 2012 2:11 pm Post subject: |
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Your findings behind the filler cap`is probably just condensed water due to the short trips, I`ll guess it still is rather low temperatures at this time a year...also down at your place.
10W-40 oil shouldn`t be to thin in this engine.......Ì would first tried to change the oil (contaminated?).......
if the problem remains, then checked the oil pressure.
Inge K. |
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drikko Flying Brick Rider
Joined: 20 Nov 2009 Posts: 1966 Location: Brisbane, OZ
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Posted: Fri Mar 16, 2012 6:24 pm Post subject: |
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I tried fully synthetic Mobil 1 15-40 (I think) in my RS but it fell through like it was a sieve, clouds of smoke and the level dropped quite fast, no leaks, just burnt, switched back to my normal dino 20W-50 usually Valvoline XLD and it's all good again. Not sure why I tried the synth, it must have been going cheap. _________________ K1100RS '97
Laverda RGS 1000 '84
Jim Young Trailer Sailer 5.7M WB
DISCLAIMER:- Anything I say may have been when I was drunk so please don't take it personally.
'Bigamy is having one wife/husband too many. Monogamy is the same.'
Oscar Wilde |
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Rafal Flying Brick Rider

Joined: 05 Jan 2009 Posts: 257 Location: Wroclaw, Poland
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Posted: Sat Mar 17, 2012 7:42 am Post subject: |
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Hello!
One oil pressure flickering was caused by bad contacts on pressure sensor wiring. 1st to check, on the pump then rest of connectors.
If You want to be 100% sure about the condition of oil pump, pressure regulator, then You can remove the sensor and put there oil pressure gauge to check it the right way.
Best regards, _________________ Rafal
K1100RS is a real beast (in Marrakesh Red)
K75S is a real beauty - she has gone , but not to far .
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BMW_Mick Brick Rider
Joined: 28 Dec 2008 Posts: 36 Location: Ipswich, Suffolk, UK
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Posted: Sun Mar 25, 2012 12:20 pm Post subject: |
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Turns out that that it seems I need thicker oil. The pressure is ok but on letting the engine tick over and get hot the light came on. The mechanic thinks that it's a simple case of engine wear as the mileage is 123 thousand, and he thinks that the old oil was probably 20/50, so the problem never showed up. Soon find out as had the oil changed.
Thanks for the help and suggestions. _________________ '93 K1100LTSE, ABS1 in Black 'Connie' |
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Tim (Midland Section) Flying Brick Rider

Joined: 08 Apr 2005 Posts: 960 Location: Pinxton, Nottingham, England.
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Posted: Sun Mar 25, 2012 4:27 pm Post subject: |
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Mick,
These engines are good for 1/4 Million miles. IMHO your mechanic is talking from his **** (butt). It wouldn't be the first time a flickering oil lamp has been traced to the switch itself. Most on here use 15/40 Semi Synth or similar. Do the cheapest / simplest things first :- Oil change, switch, pump, Engine rebuild.
HTH _________________ Regards Tim,
Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
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Stoked Steve Flying Brick Rider

Joined: 01 Sep 2004 Posts: 1402 Location: Virginia Beach, VA
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Posted: Sun Mar 25, 2012 4:59 pm Post subject: |
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I've used 20/50 Mobil1 and now the 10/40 "High Mileage" Mobil1 because apparently the 20/50 is no longer available. Mine hardly burns any oil at all, maybe a 1/4 quart in between 3,000 mile oil changes.
It loves the Synthetic, runs very smoothly....
I would suspect electrics....connections in particular. _________________ Steve
Virginia Beach, VA
93 K1100RS Mystic Red SOLD
12 Suzuki DL650A VStrom |
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Scott_Anderson Site Admin
Joined: 05 Sep 2006 Posts: 3122 Location: Central Iowa, USA
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Posted: Sun Mar 25, 2012 7:47 pm Post subject: |
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You may also remove the sensor and check for any residue build up or crud on the switch. Should be clean but you never know. _________________ Ride safe.
1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold) |
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BMW_Mick Brick Rider
Joined: 28 Dec 2008 Posts: 36 Location: Ipswich, Suffolk, UK
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Posted: Tue Mar 27, 2012 5:17 pm Post subject: |
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Thanks for the suggestions guys, they are deeply appreciated. To cut a long story short, the guy at the garage did check the switch etc in my presence, as I like to watch what they do so I have a better understanding of my machine - not that I'll be doing any real spanner work as I have nowhere to do it and my physical condition would also be a restriction as well.
The original problem only manifested itself when the engine was running much hotter than usual while in heavy town traffic. On a 40 mile run at high speed there was no problem at all. Since I had the oil changed I have tried to repeat the original conditions that caused the light to flicker and having spent a very boring hour and a bit riding around town there has been no repetition.
I'm well aware of the longevity of the 'brick', a previous machine having racked up close to 300,000 miles by the time the then owner sold it for scrap (he dropped it when the rear shock failed and put oil on the back wheel).
With all the work I've had done on her I am happy that she will last another 100k at least, and I have no plans to change her at all. _________________ '93 K1100LTSE, ABS1 in Black 'Connie' |
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hfxrzw Mad Brick Rider

Joined: 30 Jan 2009 Posts: 78
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Posted: Sun Apr 08, 2012 5:32 am Post subject: |
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Did you have a look at the pressure relief in the pump? Its a spring loaded bush that is there to keep the oil at a minimum pressure and to open when the pressure could get too high (cold oil) to protect the system. These bushes can get 'corroded' and stuck, therefore not properly controlling the pressure. Easy check to make  _________________ Cheers, Rene
Greetings from Florida.
BMW K100 '85 |
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