Why oil level switch over pressure switch?

[Constant Mesh]

Yamaha used an oil pressure switch on their new bike, FZ07.

They used a level switch on the FZ09, FJR, and many others.

Is a pressure switch more expensive? Why would they use one on an inexpensive bike?

One might believe a pressure switch offers more useful info to the rider.

 

[timk]

Maybe durability of the pumps over the years??????

 

[ionbeam]

[speculation]

Oil pressure won't be low unless:

• out of oil
• plane bearing failure
• oil pump failure
• failure of oil to return to the pan (low oil level)

In modern engines all of the above are very unlikely until very, very high mileage with the exception of out of oil. How many FJR owners have written to the Forum with these problems? Even the extreme 400k mile bikes seem to have no oiling problems.

Oil level low:

• loss of oil (leaks); even tickers that were leaking oil into the exhaust didn't cause low oil levels
• failure to put in oil or insufficient oil during an oil change
• dire lean angle
• extreme acceleration(!)

These are more likely scenarios. A level sensor will detect a problem before it leads to a low/no pressure problem.

[/speculation]

 

[Geezer]

I always thought that a pressure sensor was better then a level sensor, until I discovered that the level sensor on my FJR warns me of low oil long before the level drops below the sight glass. That means it never gets to the point where low oil can cause a problem. I like it.

FWIW, my Mazda has an oil pressure gauge, right in the middle of the instrument cluster where it appears to be very important; however, the sensor is simply on/off and the position of the needle on the gauge is determined by the computer based on RPM and not oil pressure. It is just for show and the function is equal to a low pressure light. Some Mazda owners have reported that their engines have run too low on oil and broken while the pressure switch indicated pressure. The user has to keep an eye on the dipstick or risk engine failure even though the car has an oil pressure gauge.

 

[wfooshee]

I always liked a pressure sensor in my cars, because it seemed a better indicator of the engine being warm. Oil pressure remained cold high for several minutes after coolant reached normal temperature. I wouldn't hit the motor hard until the oil pressure came down to normal range.

 

[audiowize]

A coworker of mine bought an old BMW in the late 60's. This bike had an oil pressure switch with an idiot light in the gauge cluster, and he rode the bike home without incident.

He decided to be responsible and perform an oil change, and was surprised to fine 1 cup of oil left in the sump.

I would take the level switch.

 

[snackbauer]

There's no substitute for checking oil level before riding, especially one just purchased. Even a level switch can fail. I'll take a pressure switch. But with a bike as fantastic as the FJR, a level switch will do just fine.

 

[RossKean]

Simple formula for the FJR... Fill oil, check level, ride 5000 miles. Repeat.

My FJR has never needed oil between changes and I actually do have a look every couple of thousand miles. I used to check more often but the result was always the same. As far as I am concerned, the oil level warning covers the remote possibility that something holed the oil pan or the drain plug backed out. If oil pressure drops (without low oil level) than something serious is going on and it may be already too late to fix without huge expense.

 

[MotorToad]

Oil level tells you there could be a problem before it happens, oil pressure tells you you need an engine. I don't see the purpose of oil pressure at all.

Assmusing you keep an eye on the level, you'd have to ride with your thumb on the kill switch and your eyes on the light to even hope of benefitting from a low pressure warning.

 

[ionbeam]

Some Oil Pressure Gauges are actually a misnamed pressure switch, some are a true pressure gauge measuring actual pressure.

The Oil pressure Gauge that is actually a switch will tell you one moment your engine is fine and the next moment it will let you know that your boat anchor is now ready for use.

A true pressure gauge isn't worth much on a new engine because it will almost always be sitting at a steady reading, all things being new. Then over time the pressure will be a little higher when the engine is cold and drop a bit when hot. Over the years you can watch your engine age as the variation in span grows larger and changes happen quicker. With modern engines, someplace between 200k miles and 500k miles you will see the pressure approach zero when the engine is warm and at idle. When the engine gets to this point it often will start to give you a good solid RAP RAP (rod knock, not the music) noise when started cold. When pressure is nearly zero at a warm idle and a sharp rapping noise is heard on cold starting it is telling you that your >200k mile engine is getting worn out. A real Eisenstein of a gauge