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[longlast]

The idiot light is supposed to come on when pressure is less than 3 psi btw. 

You might want to verify your gauge is accurate by installing a calibrated mechanics gauge T'ed into the fitting for the oil pressure sending unit.  Most Harley shops should have the simple setup required.  Before assuming anything, I like to know what the real readings are versus the "close enough for government work" cheap gauges Harley installs.  But let's say your gauge is accurate, and when you're running down the road at 2000 rpm and full operating temperature the oil pressure is at least 30 psi (30-38 psi is the spec, most run right around 32 psi at 2000 rpm).  If the oil pressure meets the specifications at cruise speeds, but is too low at idle, it could indicate a worn oil pump, or the pressure relief valve may not be sealing completely at idle.  That has been a common issue due to poor machining of the cam plates and the shuttle valve over the years.  The aftermarket has offered many "cures", or some people have just removed the valves and cleaned them up with abrasives along with the seat in the cam plate.  At hot idle the relief valve should not be bypassing anything, but many do.

Anyhow, it wouldn't hurt to change the oil first and see if that's the real problem.  One more reason I like to do fluid changes myself; you can't always tell what the shop dumped in versus what you wanted.

Jerry

I take it when you say "sending unit" the oil pressure sending unit is an electrical unit with a electrical gauge if so that would leave room for area/
On running I couldn't say the exact pressure I only glance at it but it sits about 1 o'clock
I will "T"in  a secondary fluid test gauge 

[longlast]

Why didn't you first call and find out what they used when they changed it last time? Have you "tee'd" into the line and verified the gauge is actually working? Sounds like it is if low pressure light came on. I think you are wasting you time to just change oil hoping it will get better, it is not going to mysteriously get better unless you have somesort of blockage in system that just goes away? Doesn't normally work like that.

Because I don't know what weight oil had been put in. My thinking is maybe just maybe the oil is to light it can't handle the heat on idle.
I can't call them I don't have the receipt didn't pay much attention to the date it went in.

[ChuckB]

The previous owner of my 2000 SERG was concerned with his low oil pressure, so he went with the SE cam plate upgrade which included the better oil pump.

[MrSurly]

I just went through a big learning ordeal with this. There's a long version of the story but suffice it to say that the oiling system especially '07 and later, uses a tiny oil pump that is working at max capacity to supply enough volume for the various outlets that dump the oil on chains and tensioners etc and still be able to supply pressure for the crank and bearings. The little pinhole ports are all sized for the specified 20weight oil. The ports really dump a lot MORE oil if you use a lower viscosity.
With a perfect pump and all parts in perfect condition, and as a test, with 5w-50 my 110 would not build any oil pressure while cranking. With 20W, it immediately jumped up to 12 psi while cranking. That is a significant difference.
I would suggest that you should find out what grade of oil is in your engine and increase the weight to the next higher grade.


Sent from my iPhone using Tapatalk

[longlast]

I just went through a big learning ordeal with this. There's a long version of the story but suffice it to say that the oiling system especially '07 and later, uses a tiny oil pump that is working at max capacity to supply enough volume for the various outlets that dump the oil on chains and tensioners etc and still be able to supply pressure for the crank and bearings. The little pinhole ports are all sized for the specified 20weight oil. The ports really dump a lot MORE oil if you use a lower viscosity.
With a perfect pump and all parts in perfect condition, and as a test, with 5w-50 my 110 would not build any oil pressure while cranking. With 20W, it immediately jumped up to 12 psi while cranking. That is a significant difference.
I would suggest that you should find out what grade of oil is in your engine and increase the weight to the next higher grade.


Sent from my iPhone using Tapatalk

Thanks MrSurly, I will do the oil change to 20w-50 then I'll know I'm running the recommended "W" oil and go from there

[donvito]

All oil pumps since 07 I believe are high volume pumps so that means more oil is being distributed and any rpm, as compared to older style pumps, if anyone remembers the old evos, shovels folks would drop the idle to like 600+ to get the lopey sound that starved the motor for oil.
It is safe to say as long as your light doesnt come on youre ok, since you said yours did and didnt give all the details of the temp and conditions when it happened, your oil may have been so thinned that it did drop to the point of low psi at idle. I had a 103 that in 110* heat flash the light at idle and that was with a Feuling pump.