Topic: Oil pressure light on after highway speeds?

[dusterdude]

gtx is fine,i use 10w40

[Klark Kent]

HElpful advice from someone who doesn't post in the forums:


Just happened to read your post about the oil light.  I don't contribute to the forums anymore.

I don't believe your mixture or your tappet clearances have any relation to your oil light issue.

The oil light comes on when the oil pressure is low or the sending unit is faulty or plugged up.
The sending unit has a diaphragm, a spring, and an electrical contact.   Pressure exerts force on the diaphragm, pushing against the spring, and releases electrical contact pressure, dousing the light.

The diaphragm might become brittle with age as most rubber/plastic does.  This and a plugged pressure hole can require higher than normal pressures to make the light go off.

Look inside the tappet covers.  If there is an abundance of oil, the pump is probably doing it's job, and your engine is still healthy...for now.

Or, if your engine has high mileage (more than 30K), your oil pump might not be making good pressure.  A new oil pump or a refurb of your current one is then in order.

Your oil leak under the sprocket cover can be caused by the shift shaft seal, the oil sending unit leaking, or the oil pump cover seal leaking.

A leaking shifter seal won't cause low oil pressure.  But, this is an indication that your oil pump(s) are still okay.

Look under the sprocket cover for the oil leak source.  If it turns out to be from the oil sender, the diaphragm is punctured, the electrical contact contaminated, and replacement is in order.

Your top of the engine breather tube should connect to the side of the air filter box.  That is where your breather element is located (at the bottom).

Good luck!

[Klark Kent]

And a follow up answering some questions i had about the initial PM:

Pick any tappet cover that you can get to easily.  I'd pick the #1 or #4  intake side to keep oil off the headers.  Pack some rags around it, pray for splashes when you run it.  Happily clean any escaped drippage.  Look inside.  Everything should be major oily wet in there.  If you can find some small clear plastic cups, you can hold them over the tappet hole and watch the splashes.  I have some K&B measuring cups I got eons ago that are perfect for this.  Those small glass jelly jars would work well for this, too.

Anyway, if the top end is getting well lubed, then chances are that the oil pressure is good and the sensing is bad.  Running the engine will be fine in this case.  I can't, however, bless your engine and absolve it from harm sitting here in my chair.  Were it me, I'd stick a gauge on it, or swap another sensor from my fleet.  Might even be possible to clean the sensor hole after removal, providing it's internal diaphragm is still intact.

I'd also go back to "motorcycle" oil at my earliest convenience.  Car oil is fine if you can find some manufactured in the 70's or 80's, or to those specifications.  I use Honda HP-4 10-40 in my bikes year round.  I'm going to try some golden Spectro next time, just to save a couple bucks.  But, even the Honda oil is cheaper than any engine work to the internals.  Just a gasket set is how much?  And, internal parts aren't getting any easier to obtain. Cheaping out on oil just seems like false economy, to me.

[csendker]

Kal-El:

Sounds like you're making good progress.  I haven't been ignoring this thread, but I've been on the road for damn near the whole month of August.  The cover hiding the shifter seal holds nothing but gunk, you can pop it off without having to dump oil or whatever, it just encloses the front sprocket, etc. No seals, just on & off.  There's a thread somewhere when I changed my seal - good advice on getting it out in it.  I agree the shifter seal - #2 in the pic - has nothing to do with the sending unit, but will make a mess under the cover & drip if it's shot.  Once you know what to do, it's an easy change-out.  I changed mine, and then found the oil pump cover leaks just a little too.  I recall it's a funky sized seal, so I'm holding off for winter.  The oil pressure switch sits on top of the pump - #1 in the pic - and monitors the pressure right at the pump, but unless it's a monster leak, I doubt it will really impact the switch.  A clogged or shot switch will.  I briefly looked into where an oil pressure gauge could be added to a 550, but there was no convenient spot for a permanent one so I gave up.  To test the switch, or pump really, I recall there's a port on the "points" side of the engine that can be used, but would suck for a permanent installation.  The idiot light is good to have, but good lubrication is the real deal, so if you have good pressure -check with gauge- and good distribution -check with jelly jars on top- then I'd be inclined to drive it while looking for a replacement sending unit.

...and I've been using Shell Rotella T dino oil.

[dusterdude]

klark,as far as lubrication is concerned,any automotive oil is fine for our engines,the only caveat being the clutch issue.ive been running castrol gtx 10w40 for over a year in my bike and have no clutch problems at all.

[edbikerii]

I had this same problem on my '77 CB550 after changing my oil to Rotella T 15W/40 a couple of weeks ago.  My bike has about 25,000 miles on it, so bearing wear *should* not be a problem.  I had been using Castrol GTX 20W/50 for many years with no problems, but I had heard that shifting would be much smoother with Rotalla T.

After warming up for about 10 miles or so, the "Oil" light would come on at stop lights or other low-RPM situations.  If I revved it up over 2,000RPM, the oil light would go out.  Shifting was no better with Rotella T 15W40.  than with Castrol GTX 20W50.  In fact, it was much harder to shift into Neutral.

I tried replacing the sender, but that didn't fix it.  I put in a bottle of STP oil treatment hoping to thicken up the viscosity, but that didn't fix it.  My next step was to change back to Castrol GTX 20W/50.  That fixed it.  Shifting is much smoother with the Castrol GTX 20W/50, too.