No oil pressure: regulator?

[raindrift]

Last night, someone backed into my bike and knocked it over.  They broke the clutch lever and turn signal and bent the sidestand, which is a pain, but not a really big deal (the bike's already been dropped a few times, so a couple more scratches won't really show).

The real problem is that the oil pressure light won't go out when I start it.  I can rev it up, and the light still stays on.  It seems to run okay (I warmed it up and got maybe 1/2 a block before I noticed), but I'm not about to ride it without any oil pressure...

I checked the wiring by disconnecting the wire from the sender and grounding it, and it's working fine.  I figure the problem is one of:

- sender
- pressure regulator
- something blocking an oil passage, or stuck over the pickup screen
- oil pump

My best guess right now is that the regulator's stuck open.  I'd love to check it out, but I can't find any reference to it in my Clymer book.  Does anyone know *where* on the engine this pressure regulator is located?

Also, does anyone know what the threads on the sender are?  I heard 1/8" NPT, but that doesn't seem right -- wouldn't they be metric?  I'd like to know so I can make an adapter to test the oil pressure.  I have a couple old gauges laying around that I could plug in there...

[John Bates]

You have probably already checked this, but just in case, how is the oil level? :dunno:

[cummuterguy]

maybe a hairline crack somewhere allowing air to interrupt suction? filter housing or oil pan area? may not be a wide enough crack for oil to leak immediately, but air may be able to get in since it's thinner.

Also, the pipe thread may very well be 1/8. my metric tap and die set came with a 1/8 npt and right under that it reads 27npt. (same size in both?) :dunno:

[The Buddha]

The GS I believe does have a 1/8 pipe thread sending unit ... can check and tell you for sure ... now that 1/8th pipe is the most confusing thing under the sun ... Its not exactly 1/8th anything ... the diamater of the pipe that its supposed to fit on is 1/8th inch. 1/8th pipe thread is some aircraft standard fitting that has been used first by the brits I think ... anyway, its 27 threads per inch and its got a significant taper ... So taking it out and putting it back in ... be very very careful ... no over tightening ... cos you will split the housing it sits in ...
Now oil pressure ... OK cavitation ... you got air in the pickup ... sometimes may take 4-5 seconds or more ... if it got oil it will pump up ... and while its bad, not much worse than 3-4 cold starts ... OH ... make sure you do have oil like he said ...
Cool.
Srinath.

[Bob Broussard]

The oil pressure sending unit is under the ignition plate under the ignition cover. On the clutch case (just under the ignition cover) is a chrome plug bolt. Unscrew that and connect a pressure gauge into it. It is bigger than 1/8 pipe thread, so you'll need to use some adapters. Or you can just pull the ignition cover and use the sending unit hole.  

Most likely it's a bad sending unit. I've been through 3 on my Ducati. :x

[Blueknyt]

yeah, Considering drilling and taping a hole for a mechanical Oil pressure Gauge myself, Idiotlights dont tell me anything other then the bulb works.
was considering a temp gauge too, but didnt know if water temp gauge would be useful as oil gets hoter then water would.

[scratch]

Last night, someone backed into my bike and knocked it over.

Sorry to hear that.

...but I'm not about to ride it without any oil pressure...

Check oil level.

- pressure regulator

Doesn't have one.

My best guess right now is that the regulator's stuck open.  I'd love to check it out, but I can't find any reference to it in my Clymer book.  Does anyone know *where* on the engine this pressure regulator is located?

The pump creates all the pressure needed. The crankcase is vented. And, the only pressure regulator is in the oil filter, but that doesn't affect the sending unit.