To set the scene, I fitted a second hand Nevada engine with gearbox to my V50II, so have no real history of the engine. It is fitted with foam type filters and electronic ignition from NBS. The engine has run well for about 1000 miles, but yesterday after a run of 60 miles the oil pressure light came on. The engine sounds fine, but when hot the oil light is permanently on. When cold the light illuminates with the ignition on but engine not started. When started the light goes out. There is plenty of oil in the engine and no obvious leaks, although I think there is a bit of black smoke in the exhaust which I haven’t noticed before.
So what to do now ? Any suggestions gratefully accepted.Â
More details please. What age/mileage on the replacement engine? Since last service? Does the oil light illum. after two miles or ten miles? Do the rocker covers become unusually hot? How much oil is it consuming?
I’m imagining a blocked oilway or faulty sensor from this distance.
Phil
The engine was from a 97 Nevada with about 40 000 miles on the clock. Oil was changed last about 500 miles ago. I rode the bike for about 60 miles then stopped for about 5 minutes and then set off again. The light came  on after 2 miles. The rocker boxes weren’t usually hot. It restarted and ran smoothly, but light stayed on. After about 3 hours it restarted, and ran smoothly and the light went out.  Concerning oil usage, I have just checked the level in the cold engine and I would say that it it is at the same level as when I checked it a couple of weeks and 100 miles ago,Â
I think I’d try a new switch before anything else. If the engine is not noisy, a faulty switch seems more likely to me. I have a vague memory that the switches used on some Guzzis can leak internally messing up the switching point.
Ian
Yeah - sounds like a switch fault.
What they said! Had this exact same thing happen on a Triumph
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Have ordered new switch and will post the results, thanks to all for the advice.
oil pressure problems on small block can be down to several problems
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 faulty oil pressure light switch  , cheap and easy to fix although it takes longer to get the air box out the way than to change the switch.
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cracked oil filter housing, had this twice on my v35, sump was warped.
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internal oil pressure loss when sump gasket leaks internally, this looks to be why my monza engine failed
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warn main bearings/big ends ( but you would hear a racket from the bottom end)
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on v65 and v75 warn rear thrust bearings ( knocking when clutch pulled in at low revs)Â
Black smoke is usually running rich, blue is normally oil getting past the valve guides or low compression .
My ‘new’ TT had a sticky oil pressure switch, swapped out and all’s well sinceÂ
What oil are you running…? Mite sound a daft question…have you left the fuel switched on with the bike standing for any length of time…some years ago…I did just that…a float stuck and leaked fuel past the rings and into the sump…3 miles into my ride the oil light came on and stayed on…blew the pressure switch…Â
Change the oil pressure switch and see how is goes . . .Â