Oil Level Question

I have a 1982 Yamaha XJ650 Maxim. The oil level light came on and won'
go off! The oil level is ok, and this happened after the bike wa
parked. Didn't come on while riding. I wasn't able to turn up an
info in my repair manual as far as checking the circuit. Questio
is....should I replace the oil pump and/or oil level switch and assum
that will solve the problem? Could it be some wiring problem?
Any ideas anyone?
thanks,
Dre

 

I wouldn't change an expensive oil pump just because the float switch
didn't work. Yamaha probably provided a port somewhere with a plug so
you could hook up a test oil pressure gauge if you really really really
thought you had a pump problem...

How long do you let the oil stay in the engine before you change it?
3500 or 4000 miles? Are you using 10W40, 20W40, or 20W50 oil? The
latter grades of oil will thicken more than the 10W40 and that might
make the oil level switch tend to stick. I'm not saying to use 10W40 if
you live in a hot climate where the summer temperatures get up around
100 degrees. You need the extra protection of a 20W40 or a 20W50 oil in
that case. But your oil level switch might not work right...

Yamaha's decision to use an oil level switch instead of an oil pressure
switch is annoying. The damned oil level switches stick and the light
doesn't come on. My FZR-1000 has a self test feature when I turn the
ignition key on. There is an oil level test relay. It tests the light
and the wiring, but not the switch, and that is bogus beyond belief! If
I designed a test circuit, it would sure as hell test everything in the
circuit...

When the oil level switch stuck after the bike had sat unridden for 2
years, I figured that the switch would unstick when I drained the oil.
The float would have to drop with no oil and should rise again when I
added oil. That didn't happen. I didn't want to drain the fresh oil and
drop the exhaust header to dick around with that stupid switch...

So I started riding again, and I guess engine vibration finally freed
the float switch up, it started working again on the highway 200 miles
from home, telling me I was low on oil...

The FZR-1000 only holds about 3.5 quarts of oil and the light comes on
when the level is half a quart low. It always seems to need oil out on
the highway, and I got tired of looking for an auto parts store when I
was out on the road a few hundred miles from home. I would have to buy
a whole quart of oil and make a paper funnel to pour the oil into the
engine through a tiny filler hole. And I would never need a whole quart
of oil, I would have half a quart left, and what should I do with it?
Throw it away? Recycle it at the auto parts store? Put it into a
plastic bag and stick it in my tank bag and hope it didn't leak on the
way home? None of those options was satisfactory...

Now I carry a 1 pint plastic squeeze bottle of engine oil in my tanks
bag, and I can just squeeze the bottle instead of dicking around with a
paper funnel...

There's one other aspect of engine oil that complicates the oil level
problem when an engine like mine doesn't hold very much oil. If I add
oil when the engine is hot, the oil will immediately expand. Then, when
I get home and the engine cools off, the oil will contract and the
level will be low, so I will add oil before starting on a trip. When
the engine is warm, the oil level is too high and the engine uses the
excess oil...

 

The oil pump is not the problem when the oil _level_ light comes on.

Theoretically, yes, but the oil level sensor Yamaha used in the
eighties is fragile and unreliable, so that's most likely the problem.
Unfortunately, they are quite expensive.

To test, disconnect the wire as close to the sensor as possible. If
the light comes on when you leave the wire unconnected and goes off
when you connect the wire to ground, your wiring is OK, and the sensor
is the problem.

The sensor contains a small glass reed switch. Needless to say,
vibration, temperature changes and age will eventually cause the glass
to break and the sensor to fail. The failure mode can be either open
or closed, but can also change between different failure modes. It can
even work properly periodically, depending on how the broken bits
rattle around inside the sensor. The glass parts are sealed inside a
brass casing, so they will not get into the oil.

I don't know your bike specifically, but on some bikes, you must
remove the exhaust system to get to the sensor. It is inserted into
the oil pan from below.

My solution to the problem: Ground the sensor wire permanently and
check the oil level frequently.