Oil Pressure Gauge
Thread Starter
Intermediate
Joined: Dec 2023
Posts: 33
Likes: 2
From: Flower Mound, TX
Oil Pressure Gauge
Hello All. I am a Newbie Corvette owner, who recently purchased a 79, L48. Question: What should the oil pressure gauge indicate at idle? I noticed that when I start my Vette the oil gauge needle goes all they way to the right and stays there until the engine is turned off, it does not matter whether the Vette is just sitting at idle, running, cold or hot. the needle stays all the way to the right. She idles at about 750 RPM and runs smooth. Is this normal? or do I need to be concern about this?
Thank you all in advance!
Thank you all in advance!
Instructor
Joined: Sep 2018
Posts: 165
Likes: 64
From: Lakeville MN
I wish I had an answer for you, my 79 did the exact same thing, I never could figure it out. I replaced the gauge and sender and nothing fixed it. I got tired of it so I installed a set of Dakota Digital gauges.
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,147
Likes: 4,258
From: US-PNW
Something is amiss, though I'd wager it's not the actual pressure that's an issue – unless a high pressure pump has been installed. Not having electronic gauges, I have no advice on that.
Normal pressure at idle should be 20-40 pounds; 10w-40 should fall just about +/-30#. Once fully warmed up, the thinner the oil and/or the more worn the engine bearings, the lower the pressure.
Normal pressure at idle should be 20-40 pounds; 10w-40 should fall just about +/-30#. Once fully warmed up, the thinner the oil and/or the more worn the engine bearings, the lower the pressure.
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
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Cruise-In VIII Veteran
Yup, try a new sending unit first. Inexpensive and easy to swap out. I've gone through a couple of them. Of course the original lasted 40 plus years. The replacements, well, not so much.
Melting Slicks
Joined: Feb 2018
Posts: 2,329
Likes: 725
From: Marietta GA
First I would remove the plastic clip to the sender unit and see what happens. If the gauge is still pegged then my guess is the wire is frayed and causing a ground. Do some serious Google Searches to see what appropriate test steps are needed before just throwing in new parts. Maybe you can find the tutorial provided by Willcox before they closed up.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Poor GRD. Its my understanding that when any gauge stays off, its lack of 12V.
When a gauge moves when power is applied, but "pegs" it's usually a poor GRD.
The oil sending unit is in an area prone for greasy connections. If a simple cleaning of the wire terminal does nothing, then sometimes it's a recently installed sender and somebody applied too much thread-sealant. The sending unit HAS TO HAVE a good ground to block to function properly.
When a gauge moves when power is applied, but "pegs" it's usually a poor GRD.
The oil sending unit is in an area prone for greasy connections. If a simple cleaning of the wire terminal does nothing, then sometimes it's a recently installed sender and somebody applied too much thread-sealant. The sending unit HAS TO HAVE a good ground to block to function properly.
Thread Starter
Intermediate
Joined: Dec 2023
Posts: 33
Likes: 2
From: Flower Mound, TX
I want to thank each and everyone of you for the information provided. None of you guys have mentioned anything pertaining to possible engine damage, and this is a BIG RELEAVE for me. I will take for action what each and everyone of you have recommended, and hopefully the issue will be resolved.
Thanks Again!
Thanks Again!
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From: Sunshine Coast, Queensland, Australia
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There's a reason no one mentioned possible engine damage. Issues with these electric oil pressure guages are common. And if you had a real oiling problem, you would clearly have other symptoms.
You never mentioned clacking lifters, or knocking rods.
You never mentioned clacking lifters, or knocking rods.
Thread Starter
Intermediate
Joined: Dec 2023
Posts: 33
Likes: 2
From: Flower Mound, TX
Hello 4-vettes. I appreciated all the valuable info you have provided me over the past week. I will check the oil sending unit and the it's ground. The engine idles pretty smooth and I can not hear any abnormal noises from, lifters, rods or valves. So far so good.
THANKS!
THANKS!
Le Mans Master
Joined: Mar 2004
Posts: 7,503
Likes: 1,511
From: Little Rock AR
You might want to do some tests before buying parts.
To test the sender: Pull the wire off the sender and check the ohms resistance across the sender terminal and a engine part (ground). The sender should have no major resistance with the engine off. Once you start the engine, the sender should have somewhere around 45 ohms. If you get over 90 ohms with the engine running the sender is probably trashed.
To test the circuit: A jumper wire from the harness wire end to a ground (with the power on) should peg the gauge to zero if the circuit is good. Gauge will go all the way to high side with the sender wire loose and ungrounded.
To test the sender: Pull the wire off the sender and check the ohms resistance across the sender terminal and a engine part (ground). The sender should have no major resistance with the engine off. Once you start the engine, the sender should have somewhere around 45 ohms. If you get over 90 ohms with the engine running the sender is probably trashed.
To test the circuit: A jumper wire from the harness wire end to a ground (with the power on) should peg the gauge to zero if the circuit is good. Gauge will go all the way to high side with the sender wire loose and ungrounded.