96meangreengt

I installed an autometer phantom electric water temp and oil pressure gauge over the weekend because I was tired of the dummy guages that are stock and have some concerns with my oil pessure. When I first start the car in the morning the oil pressure goes to 70psi and pretty much stays there even running through the gears untill the car gets up to about 180 degrees. when up to 180 going down the highway at 2500rpms the gauge reads about 68psi or so and at 2000rpms it is around 62psi, 1500rpms=50ish psi and at idle when hot at 800rpms it is sitting at 35psi. Doesn't it seem kinda high going down the highway?

anyone else running aftermarket oil presure gauges, what do your gauges show?

I use mobil one full syth 5w-30 so the oil is not to thick, motor is bone stock except for pi intake. car has 140,000 miles on it, I would think maybe lower oil pressure with higher miles but not higher oil pressure.

any ideas?

96meangreengt

Update:

went out and started the car and just let it idle.
the engine temp was 150 and the oil pressure went right to 75psi
engine temp 165=62psi
engine temp 180=50psi
engine temp 190=45 psi
all at 800 rpms.

Now when its warm and sitting at 45 psi you can rev the engine to 1500rpms and the gauge goes to 70 psi that quick. something just doesn't seems right about how fast the pressure goes up. my Haynes book says that when hot at 1500rpms oil pressure should be between 20-40 psi for refference.

uberstang1

Hmm first thing I would do is either get a different ground or make sure the current ground is a good connection.

cliffyk

What brand of oil filter are you running?

I ask because some brands (Fram comes to mind) are much more restrictive than others, and as the o/p sensor is before the filter "flow wise" higher restriction in the filter will cause the measured pressure to be higher.

I have never investigated it with the Mustang, however with the Miatas I ran for years different filters could produce as much as a 10-15 psi difference in the measured pressure.

More about that here...

ESABATM

80-90 cold
40-50 hot

90K on the clock

96meangreengt

I have the gauge and lights ground to the battery. How do you test a ground I used to know but have forgotten how to do it, I do have a digital mutimeter

96meangreengt

Im using the regualr motorcraft oil filter that you can get at walmart. This morning when i first starting it it was sitting at about 90psi. When hot at idle it will sit at 40 psi but soon as you barly rev it to 1200rpms it goes to 70 psi. I dont think its a bad connection because the gauge needle is not jerky when going from 40 to 70 is goes up and down in a nice even fashion.

I have read before that your oil pump has a pressure relief valve that when goes out causes high oil pressure. have you ever heard this?

I have half a mind to go buy a cheap mechanical gauge just to see what it says.

96meangreengt

are these readings at idle? or running through the gears?

cliffyk

With whatever is connected to the ground point turned on, check the voltage between the grounding point and the negative battery post (post, not the connector).

In an ideal world it should be 0.0V, in the real world it might be as high as 0.5V. Anything higher than 0.25V is not good, 0.6V+ is headed into bad...

96meangreengt

Not to sound dumb but connect what to what lol.

I dont think its a bad ground though because i have my battery ground run to my water temp gauge then i have a wire from the ground on my water temp gauge over to my oil pressure ground so if my ground was bad my water temp gauge would show it first.

One thing i noticed today is that when i started it up this morning it showed around 80-85 psi and stays around the 70 psi mark all the way to work (23 miles). When i get to town( about the 21 miles mark) my temp creeps up to the 190-200 range and sometimes 210 range and when that happens my oil pressure drops to 35 psi at idle and 60 psi at 3000 rpms which seemd about right. from the time i leave the house untill I get to town my car never goes over 180 degrees, then like i said around the 190 mark the oil pressure seems to be right

Is the fact that my car only gets to 180 going down the road the reason why my oil pressure doesn't drop?

I also forgot to mention the oil i used was mobil 1 high mileage full syn. 5w-30
I wonder if the high mileage oil has anything to do with it?