digital oil pressure gauge showing 1psi...??

[Ben_Pow!!]

So I've noticed that my oil pressure recently has been pretty low at idle, and the dummy light came on a couple times. I'm trying to figure out if it's the sending unit, oil pump, or bearings, so I bought a cheap oil pressure gauge to verify the pressure. I popped out the sending unit (for the gauge, not the dummy light), and plugged in the new sending unit w/ an adapter. I fired up the car and the gauge reads 1, sometimes 0. This is a cold startup, I know the pressure is good, am I overlooking something obvious here? The installation is straight forward, + & - to the battery, and a green wire to the sending unit. I unplug the green wire and the gauge shows the max reading.

2" 52mm Digital Red LED PSI Oil Pressure Press Gauge with Sensor for Car Truck | eBay (http://www.ebay.com/itm/2-52mm-Digital-Red-LED-PSI-Oil-Pressure-Press-Gauge-With-Sensor-For-Car-Truck-/160913594017?hash=item25773296a1&vxp=mtr)

[DocWalt]

Sounds like a busted gauge or sending unit.

[Alan92RTTT]

Could just be a bad gauge? I do like those prices for a digital one, I may have to get to and replace my analog one.

[Ben_Pow!!]

Yeah, think I may run it over to hydraulic shop and see if they can test it for me before I return it.

[Ben_Pow!!]

Oreilly has a mechanical one for around $20, but it starts at 10psi.... not sure if the resolution is going to be accurate down that low.

http://www.oreillyauto.com/site/c/detail/EQU0/6244/N0528.oap?ck=Search_oil+pressure+guage_N0528_-1_2313&keyword=oil+pressure+guage&pt=N0528&ppt=C0134

[anyonebutme]

If there's only 1 wire to the gauge, it relies on the engine for a ground. Don't use Teflon tape on those gauges, since it'll block the connection, use something else or just nothing if just for testing.

[CoopKill]

If your oil pressure switch is coming on, and your gauge is low you have pump, or bearing issues.

It is rare both the sender, and the switch will malfunction at the same time. The switch activates the dumby light below 11psi. If you need a pump, you might as well do bearings too, and visa-versa.

[Ben_Pow!!]

If your oil pressure switch is coming on, and your gauge is low you have pump, or bearing issues.

It is rare both the sender, and the switch will malfunction at the same time. The switch activates the dumby light below 11psi. If you need a pump, you might as well do bearings too, and visa-versa.

Yeah, my actual gauge has always been extra slow and wonky, worse than any of our other 3s's, so I just wanted some verification on the actual pressure. Fairly new rebuild, but 180,000 miles on the pump. I was planning on checking the bearings while I was in there, guess that is quite a few miles on the pump, should probably replaced anyway. Just trying to avoid all that if it's just a sending unit problem.

[Alan92RTTT]

The switch activates the dumby light below 11psi.

I could swear I had been told 5psi for the idiot light.

[stealthee]

I've always read 11 psi.

[CoopKill]

Just confirmed in the manual.

[Ben_Pow!!]

If there's only 1 wire to the gauge, it relies on the engine for a ground. Don't use Teflon tape on those gauges, since it'll block the connection, use something else or just nothing if just for testing.

That was it. I bench tested it hooking a ground straight to the sending unit, and blew a little air into the port, and the gauge showed pressure accordingly. I removed all of the teflon and re-installed. I'm getting about 23psi during warmup, then after a few minutes drops to 12.... once completely warm, only 5psi. Looks like I'll be getting my hands dirty this weekend, ugh. Hopefully the bearings check out as well.

[Alan92RTTT]

I've always read 11 psi.


Just confirmed in the manual.

Thats good then because my manual gauge has been known to dip below 10psi on hot idle. Good to know its not really running lower than 11

[new93TT]

where you guys hooking up your mechanical oil pressure gauges too?

[stealthee]

I would personally never use a mechanical gauge due to the possibility of the line rubbing through and leaking, however you would use an adapter and run it where the factory oil sender screws into.

[new93TT]

ok so just get electrical one an run it with which psi sending unit?