oil pressure light - Page 2

**Ranger** · #16 (**permalink**) 10-10-09, 07:45 PM

I hate to admit it, but I actually used that crap when I was younger and more gullible.

Freakzilla · #17 (**permalink**) 10-11-09, 11:41 AM

Quote:

Originally Posted by fatngs

i replaced the oil sending unit; right after, about 15 min after driving it did it again only the oil light would come on at anything under 1000 rpm

i was on my way to a doctor's appointment so i had to keep going; i pretty much braked with my left foot and kept my right foot on the gas to keep the revs up

however, on the way back it was fine and havent had the problem since

also i havent changed the oil yet

Mine did the same thing. It came on once after changing then never again.

Freakzilla · #18 (**permalink**) 11-05-09, 10:08 AM

Now it's back.

I had my transmission rebuilt, and when I drove it home, the "Low Oil Pressure" warning chimed constantly.

Back story:

When this problem originally started, my oil was low when the warning came on. From then on it only came on when idling in drive.

I changed the oil pump and bought a new sensor from Napa, but it was the wrong size so I put the old one back on. The warning never came back, until I picked it up after having the tranny rebuilt.

I bought a sensor at Autozone and when replacing I noticed water between the pigtail connector and the sensor. I guess the transmission place pressure washed it.

I cleaned out the pigtail connector with quick dry electronics cleaner and replaced the switch. No message until a day later.

I changed the oil and put 5W-30, is that too light? Light enough to cause the warning?

I plan on trying a Napa sensor to see if that makes a difference...

submariner409 · #19 (**permalink**) 11-05-09, 10:17 AM

I believe your engine is spec'd for 10W-30 oil, year 'round. If it's not too much of a hassle, change the oil again and use a WIX filter.

5W-30 may well give you an idle speed oil light when hot.

Freakzilla · #20 (**permalink**) 11-05-09, 11:44 AM

Quote:

Originally Posted by submariner409

I believe your engine is spec'd for 10W-30 oil, year 'round.

When putting the filler cap back on (of course) I noticed it said 10W-30. So I checked in the Hayse manual and it said you could use 5W-30 in cold weather. However, it doesn't get THAT cold in Atlanta.

Quote:

If it's not too much of a hassle, change the oil again and use a WIX filter.

5W-30 may well give you an idle speed oil light when hot.

WIX filter?

I've got a Bosch Premium filter on there now.

Freakzilla · #21 (**permalink**) 11-05-09, 01:13 PM

OK, Wix is a brand of filter. I see O'Reily's carries them. I've never tried them before. Better?

submariner409 · #22 (**permalink**) 11-05-09, 04:02 PM

Go to http://minimopar.knizefamily.net/oilfilters/index.html and http://minimopar.knizefamily.net/oil.../opinions.html to form your own opinion on oil filter use. Also read http://www.carbibles.com/engineoil_bible.html

I now use WIX for most applications, but for many years I used Purolator.

Freakzilla · #23 (**permalink**) 11-06-09, 09:45 AM

I haven't changed anything yet but I'm starting to think I might have a bad wire somewhere.

The warning seems to come and go completely randomly. Like yesterday, I came to a stop on the interstate and it came on. Then once off the interstate I stopped at two red lights and it didn't.

Freakzilla · #24 (**permalink**) 11-15-09, 09:43 PM

I put 10W30 in and cleaned out the connection again.

I tightened up the sensor, it was showing a little thread still, could that make a difference?

submariner409 · #25 (**permalink**) 11-15-09, 09:53 PM

No, the number of threads showing has no bearing on sensed pressure: The pressure in a hydraulic system (your engine oil pressure system is one) is equal at all points in the system: oil is incompressible. Flow rates differ according to clearances, but pressure is constant throughout the system.

Freakzilla · #26 (**permalink**) 11-15-09, 10:50 PM

That's what I figured.

Something else I noticed and just remembered... while cleaning the pigtail connector, I noticed one of the contacts was kind of brownish in color while the other two were silver (aluminium?) colored. Could the water in there have corroded that contact or something? That pigtail connector is $25!

The low pressure message hasn't come on since I changed the oil and cleaned the sensor but I only drove it about 6 miles to the Kroger and back. I'll find out for sure tomorrow.

Freakzilla · #27 (**permalink**) 11-17-09, 03:00 PM

I found this info in the FSM and there's some things I don't understand...

Quote:

DESCRIPTION
This oil pressure indicating system incorporates an instrument voltage regulator, electrical oil pressure gauge and a sending unit which are connected in series. The sending unit consists of a diaphragm, contact and a variable resistor.

OPERATION
As oil pressure increases or decreases, the diaphragm actuated the contact on the variable resistor, in turn controlling current flow through the gauge. When oil pressure is low, the resistance of the variable resistor is high, restricting current flow to the gauge, in turn indicating low oil pressure. As oil pressure increases, the resistance of the variable resistor is lowered, permitting an increased current flow to the gauge, resulting in an increased gauge reading.

Service and Repair

Disconnect the oil pressure gauge lead from the sending unit, connect a 12 volt test lamp between the gauge lead and the ground and turn ignition on. If test lamp flashes, the instrument voltage regulator is functioning properly and the gauge circuit is not broken. If the test lamp remains lit, the instrument voltage regulator is defective and must be replaced. If the test lamp does not light, check the instrument voltage regulator for proper ground or an open circuit. Also, check for an open in the instrument voltage regulator to oil pressure gauge wire or in the gauge itself. If test lamp flashes and gauge is not accurate, the gauge may be out of calibration, requiring replacement.

1. Where is the instrument voltage regulator?
2. Where is the electrical oil pressure gauge?

Hopefully I'm going to have a little time to work on this on the weekend.

I've got a mechanical oil pressure guage I'm going to hook up and see what the actual pressure is first.

(11 psi at idle, 53 psi at 2,000 rmp per the FSM)

I'm not sure how I could run the mechanical oil pressure guage oil line into the cabin, any suggestions? I guess I could just crack the window.

But since the warning only comes on at idle, couldn't I just test it in the driveway?

Freakzilla · #28 (**permalink**) 11-23-09, 08:24 AM

I put in an AC Delco part from the Caddy dealer.

Fixed.

Freakzilla · #29 (**permalink**) 11-24-09, 08:59 AM

Quote:

Originally Posted by Freakzilla

I put in an AC Delco part from the Caddy dealer.

Fixed.

BETTER, but not fixed.

It doesn't go off in park now. I think I'll step the oil up a weight to 15W40.

cadillac_al · #30 (**permalink**) 11-25-09, 09:29 AM

When I got a good deal on some 5-30 synthetic and put it in my old old 4.9, the oil light started coming on at idle. I immediately changed it to 15-40 since spring was coming soon and the oil light never came on again. I wouldn't run 15-40 if the temps get below 0 degrees though. Just my $.02.