Oil pressure issue?

[mooshie]

I have a B18C turbo and today noticed that my oil pressure gauge was reading very low. Car seems to be ok, running smoothly etc so I am wondering if it might be just the sending unit that is failing?

Was reading 25-35PSI (!) from about 3k rpm and at idle dropped to zero, I also noticed a couple of flickers where the needle quickly went up to 50-75 psi when under a bit of load. My stock oil light never came on (at what pressure does this come on?)

Sender is attached to an oil cooler sandwich plate and on the return side to the engine from the cooler. oil was about 2/3rd on the dipstick when I started the drive, I put about 700ml of oil in when I first noticed the low pressure

Is it possible for the oil pump to fail in this manner? I thought when they went it was more of a catastrophic thing and you lose all pressure. Anything else that could be causing these symptoms?

[cbauto]

First diagnosis would be to try known working sender/gauge

[stndrd]

What oil are you using and how long has it been since it was serviced? If the oil has sheered (lost viscosity) this may be causing an oil pressure issue. First thing I would do tho, would be plug and oil pressure gauge into the OEM oil pressure switch location and check your oil pressure that way. This will tell you if you have a faulty electronic sender or if the motor is lacking oil pressure

[chez00]

Is it possible for the oil pump to fail in this manner? I thought when they went it was more of a catastrophic thing and you lose all pressure. Anything else that could be causing these symptoms?

Oil pumps rarely fail completely. As bearings wear, more oil bypasses due to larger clearances and thus pressure drops. It's a "slow and steady death" kinda thing and not usually related directly to the actual oil pump but clearances opening up. As Josh said you need to verify the actual operating pressure with a mechanical gauge.

[rc_]

Was reading 25-35PSI (!) from about 3k rpm and at idle dropped to zero, I also noticed a couple of flickers where the needle quickly went up to 50-75 psi when under a bit of load. My stock oil light never came on (at what pressure does this come on?)

Sender is attached to an oil cooler sandwich plate and on the return side to the engine from the cooler.

Is this gauge newly installed? Assuming it is an electronic type gauge, check the sender body is earthed properly and that the signal wire is securely installed. If it is try installing a new signal wire from the sender to the gauge.

I had similar issues with my oil temp gauge mounted off a sandwich plate, it would work correctly for 15 mins or so then start dropping off completely. In my case it was because the body of the sender wasn't earthing properly through the anodised body of the sandwich plate.

[mooshie]

Gauge has been installed for a few years now with no issue, if it was a loose connection then I wouldn't get any reading at all? Checked connections and they all seem fine. Oil is Nulon 5W-40 and I change it every 6 months which is usually less than about 3000km, still looks pretty clean at the moment and it's been exactly 6months today since last change. Pressure was fine when I started out on the drive as far as I recall so I am hoping it's not the pump worn out! I'll need to get it to a shop to get them to test with another gauge, so would this be ok to drive the 6km to get there? Or not risk it.

Maybe I would be better off buying a cheapie mechanical gauge and hook it up. 1/8th BSP if memory serves?

[rc_]

It may be ok to drive assuming your factory oil pressure switch is working properly, does the oil light come in when you turn the key to on before cranking?

check the wiring to the back of the gauge to make sure it hasn't come loose or broken too. You should have power, earth and signal wires as well as separate power/earth for the light if it is backlit. Make sure it is getting 12v with ignition on

Btw all the gauge senders I have seen are 1/8th NPT not BSP.

[mooshie]

Yeah I think most senders are NPT but the OEM fitting is BSP? Can't remember from when I installed everything originally..

Oil light comes on for about a second when I turn the car on, same slight delay as always due to pressure building up through the oil cooler, just tried now while engine was cold and it went to about 20psi, should be about 50ish. Will check voltage tomorrow.

Starting to think I may have a bearing issue from reading a few threads on HT and Team Integra, or maybe I am just over-worrying! (Or hoping for a bigger boost rebuild...lol)

[rc_]

Not sure on the thread of the eom pressure switch, sorry can't help there.

I think the oem switch only activates at very low pressure though so I wouldn't expect it to pick up a problem until it is fairly severe.

Sender units are cheap though, may as well do as you were originally thinking and try another one before going too much further.

On my stock b18c the oil pressure is pretty much 100psi dead cold on first start up, when it heats up above 80 ish deg pressure is 30-40psi at idle If I remember correctly. As soon as I'm anywhere off idle pressure jumps straight up again.

[mooshie]

So I picked up a cheapie 100psi pressure gauge, hooked it up to the same port where the sender was annnnd-



70psi at cold idle and dropping progressively down to 26 as the oil warmed up ie: perfect!


Need to get a new sender and this time will remote mount on the firewall so the engine vibrations don't hurt it