Oil Pressure alarm 5.3
 

Left the house this AM and when I got to the stop sign turned the corner the alarm and dash reads oil pressure? and the gauge is fluctuating down from 80 to zero.
Checked the oil and the dip stick says FULL
any suggestions?
The truck is stock with 80K miles

Re: Oil Pressure alarm 5.3
 

analog or digital OP gauge? Check your sender or oil feed. If the gauge is correct, then it might be the oil pump o-ring.

Re: Oil Pressure alarm 5.3
 

The analog gauge (dash) was fluctuating, I will try a additional analog at the oil filter bypass first.
What is the color of the good O ring if I need to replace it?

Thanks Br3w

Re: Oil Pressure alarm 5.3
 

If its using the 1/8 nylon line, it might be kinked or has air in it. Mine had a slow weep when the oil got hot and would piss a little bit of pressure and make the gauge go goofy.

O-ring depends on which pickup your using.

Re: Oil Pressure alarm 5.3
 

Is this a stock '99-'07 Silverado? If so, the oil senders are known for going bad.

Re: Oil Pressure alarm 5.3
 

Well I guess I will start with the aux. oil pressure gauge and see if it is reading correctly.
The stock oil pressure gauge does not look like it will be fun to replace!

The truck is a stock 03 1/2 ton 5.3 with 80K and it has been well taken care of.
The oil and filter have about 1000 mi since a oil change and the filter is a Wix.

I am leaning towards the "O" ring, but I will know soon!

I am going to pick up a "O" ring this AM, what color is the "good" one???

Re: Oil Pressure alarm 5.3
 

If I unhook the sender it will set the alarm correct, is there a procedure to test the sender besides R & R?

Re: Oil Pressure alarm 5.3
 

I hooked up a Aux. mechanical gauge and it reads 42# at idle with a increase in RPM's it goes up to 50# and the dash reads 80# all the time, so I'm gussin start with the sending unit!

Re: Oil Pressure alarm 5.3
 

Thanks,
I' m off looking for a new sending unit

Re: Oil Pressure alarm 5.3
 

I have personally never seen an oil pump O ring just go bad, they are usually only a problem if they've been taken apart. I have however seen many sending units go bad and leak oil. That said, if the gauge is stuck on 80, it could be the stepper motor for the gauge that is bad, they're notorious for going bad too, and although not as easy to replace as the sender, they are not really that hard to change either. I would start with the sender if it were me though as I don't think a bad stepper would trigger the low oil pressure message on the dash.

Re: Oil Pressure alarm 5.3
 

Once the steppers go bad, don't they just stop dead? Oddly enough all my GM vehicles either have good luck, or aftermarket gauges lol.

Re: Oil Pressure alarm 5.3
 

Just tried it this AM, I do not think it was the Oil pressure gauge as it still sets the alarm low pressure!
I am going to attack the "O" ring, what color?

Re: Oil Pressure alarm 5.3
 

You tried the sender and it still didnt work?

Re: Oil Pressure alarm 5.3
 

This AM the Low Pressure alarm went off so I am going after the "O" ring on the pick up tube

Re: Oil Pressure alarm 5.3
 

Did you replace the sending unit yet?

Re: Oil Pressure alarm 5.3
 

Yes, what a PITA !

Re: Oil Pressure alarm 5.3
 

O K, all looks like everything is working
This the coolest time we are going to have for a few months and no alarm this AM
The new gauge is now reading what the Aux. analog one was reading a few days ago, before the sending unit was changed 40#