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Discussion Starter · #1 ·
I replaced the oil sending unit when I rewired everything. I was just wondering if anyone else has had this problem. It takes about 5 minutes for the gauge to start working. When it does, oil pressure is good. Could I have air in the sender somewhere? And it take this long to start working because of the air?
 

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If you still have the old sending unit, you could put it back in to see how it behaves. Perhaps the new sending unit is the issue.
 

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This is a crazy idea, but are you sure somebody hasn't mixed up the wiring for the oil sender with the wiring for the temperature sensor?

The temp sensor would explain it taking time to start working since it takes time to warm up.

It's a pretty unlikely scenario but it's at least worth glancing at the wire colors.
 

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Discussion Starter · #5 ·
The wires aren’t mixed up. I double checked that. I figured that was what I had done. It is not a mechanical gauge, the original electric one. After driving and stopping and starting a few times, it got better. It was just the initial start ups when this happens.
 

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5 seconds would be normal 5 minutes is a problem and the problem isn't air.
 

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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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The sender works by a ground. If you have a helper have them watch the gauge with the car off. Take the wire off the sender. Have them turn the ignition to "on" (don't start the car). Then touch or hold the wire to a good bare ground on the engine. The gauge should respond by instantly going all the way up the scale. If it does, something is skewed with your sender. If it doesn't respond, then something is wrong with the gauge or in the cluster. (You can test the basic operation of the fuel and temperature gauge senders the same way.)
 

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Did someone use a liberal amount of teflon tape on the sender or sender extension when installing? None should be used... it's a pipe thread and, thus, tapered. If you MUST use something on the threads use a liquid or paste petroleum-safe pipe dope.
 

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Discussion Starter · #10 ·
Add another thing to this post. The fuel gauge is right beside the oil gauge. Noticed today that the gauge is on full all the time. I thought it was the sending unit. But watched the gauge and it will drop to empty when key is off. Goes very slow getting to empty, and very fast getting too full. Would it be possible that I have mixed the two wires up that go to each gauge or the constant voltage regulator is bad? I changed the regulator when I had the dash out. And one more thing, sorry if I make a lot of stupid post, but I don’t have anyone around here to ask for help. I appreciate everyone on here helping this old man.
 

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if the original sender isnt leaking or other wised damaged you can soak it for a day of two
in kerosene, carb cleaner even acetone or lacquer thinner, pretty much any solvent will do.

then blow out the hole, you can chase it with a small wire and re-soak it

99% of the time its just clogged up

my sender is still original going on 50 year and still works

Ive had to clean it up about 3 times in my life.
 

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Could it be the new wiring harness has the oil pressure lead mixed up at the plug that goes through the firewall? Another words does the white-red wire in engine compartment plug into the white-red wire on the other side of the firewall. I once had a 3 wire alternator pigtail while doing a 12 volt conversion on my 53 Hudson that was reversed at the factory. Colors were in the correct location, but when you checked continuity on it was clearly wrong. Good luck.
 

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...Would it be possible that I have mixed the two wires up that go to each gauge or the constant voltage regulator is bad?
...
It sounds like you're on the right track there.
 

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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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You can again prove out your question simply by doing the same test I suggested before. Ground the wire off the oil sending unit and seeing if the gauge (or the incorrect gauge) goes all the way up to the maximum reading. I prefer to do this with two people because sometimes what you think is a good ground on the engine may not be. So you have someone to watch the gauge to see how/if it reacts while you fiddle the wire around. Or you might run a jumper wire from the sender wire all the way over the the battery ground terminal which you KNOW is a good ground. Or use a test light to find a good ground . A pro mechanic version of doing this type testing might be to use a commercial tool like a "Power Probe".

Basically ground the sender wire somehow, with the key on, and see what happens.
 

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Discussion Starter · #15 ·
I haven’t taken the dash out yet. I will this weekend. But, looking at the wiring schematic, I think I know what is wrong. The constant voltage regulator has two wires that go to it. I believe the post on the new regulator are backwards from the old one. I probably hooked the wires up wrong. I made a mental note of this before I put the new one in. But with my crazy ways, I probably didn’t switch the wires.
 
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