Tfriend80

My 80 vette has a 383 stoker which was in it when I bought it. The oil pressure is always pegged when the car is running. It does move slightly pulsing when the car idles but still very high. What is the most logical way to check to see if I have a problem?
Thanks

oldalaskaman

mechanical gauge

Lil" Red Corvette

Sounds like the sending unit to me. Disconnect the wire to the sending unit with the key on and see if it falls to zero. Than touch the wire to ground and see if it pegs (I could have this backwards). If it does both of those things try another sending unit.

7T1vette

The gauge is already "pegged". He has a short in the sender wire somewhere. The short is most likely in the engine compartment area, but there is a small probability that it is in the dash area due to the sender wire being routed over something metal and the wire insulation being 'rubbed thru' till it shorted out.

bashcraft

What does it do when the key is on but the engine isn't running?

Indiancreek

Attach a mechanical gauge to one of the ports and see what the real numbers are and see if they match those in the dash.
Some folks mess around with oil pumps at install and create all kinds of issues.

69VetteFla

Do you have a high volume oil pump? I can tell you that my pressure runs very high too. I am at 70 until she warms up then never go below 35 even at idle and back up to close to 70 when cruising.

Lil" Red Corvette

I would completely agree with you except that he said it was pulsating at idle. If the wire is shorted to ground it will peg and not move. The fact that it is trying to work at the end of the gauge range means it has to be hooked up. It could be shorted to almost ground (low resistance).

oldalaskaman

could be the wrong sender

Tfriend80

Thanks all.....looks like I have few things to check out

sstopczy

I had the same issue and you might have an oil pressure switch (for light), instead of an oil pressure gauge sending unit.

oldalaskaman

excellent

MotorHead

That's what mine does wobbles around 40psi at idle and pegs when I boot it and stays around 70psi when cruising. I have a 10% higher volume pump in mine. I wouldn't worry too much about it

AdamMeh

Mine did the same thing. They gave me a switch for a light instead of a gauge and it was "almost" pegged but would fluctuate on the high end of the gauge sweep. I ended up going back to the stock bell type switch. Works great now.

Adam

0Willcox Corvette

Oil gauge testing:

Key on:
1) Remove ohms wire from sender. Gauge should peg full, just above the face rivet.
2) Ground out ohms wire to engine. Gauge should go to empty.

If you pass this test then the dash unit is working properly and you have established the gauge has power and ground and is working. You have also verified the wire from the sending unit to the gauge is in working condition. At this point I would check for ohms output from the sending unit and more than likely replace it.

And yes.. make sure you get the correct sending unit..

The oil pressure gauge works exactly the same as the fuel gauge and on the same exact scale. It is a more responsive gauge obviously but the input 0-90 ohms is the same too.

So with this knowledge you can use the fuel gauge video to see other scenario's about what a gauge is doing when certain conditions exist.

Other tid bits to know.. When the resistor on the back of an oil pressure gauge is blown the most it will read is 20psi. It will fluctuate between 0 and 20 but that is the highest reading it is capable of.

If the gauge is missing a ground... it will go the zero... NOTE: If you do the test above and you pass, you've eliminated this as being the issue.

Fluttering gauges.. Since the gauge can only work with input then I would suspect a fluttering gauge could be either the sending unit or a wire breaking. It could have an issue inside the gauge but when the gauges get to a point where they flutter they usually just short out.

I did a video on the oil pressure gauges just like this one for the fuel gauge. I've not posted it yet, I've not had time. But you can use this gauge video for an oil pressure gauge. As I stated, they are nearly twins and the response is exactly the same.



Imho,

Willcox