Oil Pressure Drop

[ryonker]

I just recently installed an oil pressure gauge and an oil cooler on my 79 GS 750. Hook up went just fine.

Started it up last night and everything worked fine (had about 7 psi at start up and then around 3 at idle).

I just took it for a drive and I got about 6 to 8 psi when accelerating and then 3 at idle. Then I noticed my oil light flickering at idle and at gear changes. Then at idle my oil pressure dropped down to about .5 psi, but would go up when I accelerated.

Any idea what might be causing this? I do have a small leak where one of the nipples screws into the adapter. I am not sure how much leaked but with the bike on the stand there is plenty of oil, but I could be little low considering the cooler and lines store some oil too.

Thanks for any help.

Rick

[BassCliff]

Hi Mr. ryonker,

Where is your idle set? If the idle too low it might trigger the pressure sensor.


Thank you for your indulgence,

BassCliff

[ryonker]

It's at about 1000 rpms. But I will turn it up a little and see if that helps.

Thanks!

[ryonker]

But thinking about it, the pressure sensor light lights up when my pressure gauge also shows low pressure (.5 to 1 psi). So that is working as it should, right?

[ryonker]

I just added a little oil and started it up. It actually idles just fine around 1300 rpms. But at 1300 rpms the pressure is really low (about 1 psi) and the light comes on.

But (with the bike sitting in neutral) I rev the engine to 2000 rpms and the psi goes up to about 3, and the light goes off.

The funny thing is that this didn't happen until I took it for a test drive. I let it run for a while last night with no problem, and at initial start up today the psi was very acceptable.

[hampshirehog]

What oil are you running? If it's a bit warm over there you might be better with 20-50.

[ryonker]

I am running amsoil 20w 50.

[ryonker]

As an addendum...prior to installing the cooler, my oil light has never come on.

I am sure there is a reason. But I am not running it with questionable oil pressure...so I may be getting rid of my adaptor and cooler unless I can fugure this out.

[seuadr]

how much oil did you add? those coolers will hold a quart or so.. your oil level will seem fine when you measure it, but when you start the bike and get the oil really circulating, a quart is gonna be in the cooler, creating lower pressure everywhere else.

[posplayr]

Oil Cooler

The oil cooler (depending on how you routed it) will reduce oil pressure some. Apparently it did just enough to trigger your pressure switch.

What did you use as a pressure switch plate/block?

Posplayr

[ryonker]

Not even close to a quart. Maybe that's my problem. I just wasn't sure how to determine the amount.

Any thoughts? Nessism suggested running the engine then pinching the hoses. I am not sure how hard I want to pinch them though.

Should I just keep adding and see if it raises the oil pressure?

[lucabond]

Just a thought, if you placed the cooler below the height of the crankcase I am assuming its connected with rubber hose. And checked the oil level while on the center stand, the oil should flow into the cooler and you would be able
to see how it affects the crankcase level. Then add oil to the normal level this would let you know how much oil the cooler and hoses take. When you lift the cooler on to its mounts the crankcase would show high till you ran the motor. Just thinking.

[rustybronco]

stop, don't run it. adding oil won't raise the pressure.
You have to excuse me I don't know 750's, but where is the tap for the oil cooler lines, on the rear of the engines like the 2v 850's, under the pressure switch?
where are you tapping the oil pressure gauge at?

***edit*** http://www.thegsresources.com/_forum...448#post846448

[Steve]

If your block-off plate is like the one that I just helped install on TheCafeKid's 1100, there is a place to put your pressure sensor assembly. However, it appears to me that the whole concept of the pressure sensor is that pressure will cause it to move away from the electrical contacts that turn on the light. If the bore into which the sensor mounts is a bit larger in diameter, oil will flow around it more easily, instead of pushing it away from the contacts. This could be why your light is coming on. Although the block-off plate is a quality piece of work, the specs might be just a bit different from stock.

.

[ryonker]

My oil pressure gauge comes off the side of the crankcase---it's one of those from Bruce.

Yes, Steve, my oil plate adaptor is exacly like the one you installed for Cafekid.

Why would the pressure start off ok and then become a problem (if it's not the oil cooler using up more of the oil?)

Steve, what should I check then?

Thanks!