Anyway to test an oil pump?

[Nessism]

I pulled the oil pump and to my chagrin, there was nothing at all wrong with it. No sheared pin or plugged mechanism. All shipshape and Bristol fashion. So I'm no further ahead in my exploration of discovery.

Cheers,
spyug

The oil pump design is almost foolproof so my guess is the problem relates to the wiring or maybe the sensor itself. What about performing some continuity checks on the switch, both with the engine running and without? It's possible the oil pressure regulator spring is stuck allowing oil to bypass but this seems remote unless there is a lot of crud in the crankcase. Dropping the oil pan would tell the story on this.

:-\\\






"The message you have entered is too short. Please lengthen your message to at least 10 characters."

 

[tkent02]

to test the regulator you need to take it out and put 78psi through it or just take it apart to see what the spring pressure is like. its strong usually.

I did that and I could push the spring in and it returns so its not broken or seized. Thanks for mentioning it.

There should be a spec for spring tension of the regulator spring? It isn't supposed to open at all until an overpressure occurs, what is that 80psi? 100? Let's just guess that it's 80 or 100....
I don't know the area of your regulator in square inches, but let's say it was one inch. The spring shouldn't move at all until 80 or 100 pounds are applied to it? If the area was half a square inch, it shouldn't move until 40 or 50 pounds? How much did it take to move that spring? Seems like it should be a very stout spring.

 

[spyug]

How much did it take to move that spring? Seems like it should be a very stout spring.

Oh yes it is pretty sturdy. I had to bear down on it with it resting on my work bench. I'd say 40 pounds or so if I had to guess.

The oil pump design is almost foolproof so my guess is the problem relates to the wiring or maybe the sensor itself

well I'm doubtful still about the wiring and the sensor. We were able to check the function of the sensor with compressed air and it indeed did cause the lights to go out. We also switched the stock sensor for a new one and repeated the test with air and got the same result. The kicker for me is still the fact that the oil pressure test gauge I fitted showed no movement and with the sensor removed and the engine running, the oil "puked" out but didn't come out in a geyser that 50+ psi should generate. I grant you the oil pump did seem very solid and not likely to fail. The parts did seem over engineered to me.

As I said, I can't think of anything else to look at and the only thing I can think of to do is replace o-rings and button it back up. I'll do that in a day or so when I get the rings and gaskets.

Thanks for all the comments guys. I appreciate the interest and concern.
Spyug

 

[spyug]

If I read the fine print

If I read the fine print

I might have seen the warning that "if the oil pressure is too low it means that the pump is internally worn or otherwise defective and the complete oil pump needs to be replaced".

Now I did pull the pump and it looked fine but I'll admit I didn't measure anything but after reading this (had I seen it before) I would have swapped pumps with my parts bike pump right away.

My o-rings are in and I'm going to pick them up this afternoon. I will button it back up in the hopes that, despite the manual, the pump is good and oil pressure will be restored. Being a sceptic however, I'm doubtful.

As a kid, I used to build model airplanes and I'd often get myself into troubles assembling because I didn't read all the instructions. My dad, an engineer, would always admonish me, " when in doubt, read the instructions, thoroughly". Its obvious I didn't listen to him then as I'm still pretty much the same way today.

I'll let you know how it goes in the next couple of days.

Cheers,
spyug

 

[Guest]

The oil pump design is almost foolproof so my guess is the problem relates to the wiring or maybe the sensor itself. What about performing some continuity checks on the switch, both with the engine running and without? It's possible the oil pressure regulator spring is stuck allowing oil to bypass but this seems remote unless there is a lot of crud in the crankcase. Dropping the oil pan would tell the story on this.

I have to agree with Ed on this, definitely could be the sensor or wiring. I would think this would be your most PCOF (probably cause of failure).
That sensor supplies the ground to turn on the oil pressure light when the engine is off and key on, when the engine is running and oil starts pumping it opens the circuit turning off the oil pressure light and maybe some of the other idiot lights.
I had to replace a faulty oil pressure switch on my GS1100E, it was intermittant, sometimes the light would come on when I turned on the key, sometimes it wouldn't, cleaning it didn't help. Anyway, with the key on your oil pressure light should be on, disconnect it and it should go off.
If it doesn't you have a short to ground somewhere. If your light did go off when you removed the wire from the sensor, take the wire and ground it somewhere else with the key on and the light should come on. That just checks your wiring. If it checks out good, it still could be a bad sensor, it could be stuck, or touching the sides of the area around it supplying that ground.

 

[Guest]

Oh, refer to the wiring diagram, The oil pressure switch is a circled number 1, page 8-8.
http://www.mtsac.edu/~cliff/storage/gs/GS550E-ES-L_1983.PDF