oil guage
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Senior User
Joined: Jan 2000
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From: Mount Sunapee, NH
oil guage
I have 79 F250 4x4 and when i go to start the truck the stock oil guage pegs all the way out. Then when the truck is running the gauage is all the way at the left as if the truck was turned off. What is causeing this to happen? If is a bad ground somewhere? If it is a bad ground, where is the ground on the truck?
Thanks,
Jeff
Thanks,
Jeff
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Joined: Jan 2001
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From: Virginia
oil guage
There should be a oil sending unit on the engine somewhere. On most of the engines I've messed with, it's near the oil filter on the driver's side front of the engine. But I have never worked on a 429 so it could be elsewhere. It should look like a small metal can with a wire coming out of the top. Check this connection and all along the wire to make sure it's not rubbing somewhere. You can also check the guage by turning the key on and taking the wire off the sending unit. Your oil guage should peg all the way low or high. Then take this same wire and ground it on the engine block and the guage should peg the other way. If everything looks ok and the test works, I would guess you need a new sending unit.
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Joined: Jun 1999
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From: Comox Valley, Canada
oil guage
[QUOTE]I have 79 F250 4x4 and when i go to start the truck the stock oil guage pegs all the way out. Then when the truck is running the gauage is all the way at the left as if the truck was turned off. What is causeing this to happen? If is a bad ground somewhere? If it is a bad ground, where is the ground on the truck?
[QUOTE]
To me anyway, this sounds like you have an oil pressure switch for the "idiot" light installed instead of an oil pressure sender for the guage.
Meaning when you go to start the truck the switch is sending a ground signal to the "idiot" light, which you don't have, causing the guage to go full high. Then when the truck is running the ground is removed as the building oil pressure opens the switch and the guage goes full low.
Verify you have the proper sending unit installed. Good luck.
Sparky
[QUOTE]
To me anyway, this sounds like you have an oil pressure switch for the "idiot" light installed instead of an oil pressure sender for the guage.
Meaning when you go to start the truck the switch is sending a ground signal to the "idiot" light, which you don't have, causing the guage to go full high. Then when the truck is running the ground is removed as the building oil pressure opens the switch and the guage goes full low.
Verify you have the proper sending unit installed. Good luck.
Sparky
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From: Mount Sunapee, NH
oil guage
Well the body and wiring are from a 79, but there is a 390 in the truck. The wire for the oil pressure guage is on top of the oil filter bracket. I have tried 2 different engine wiring harrnesses both from 79 and they both did the same thing. Might the 90 degree elbow plug that goes to that sending unit be no good on both of those harnesses? or is the sending unit itself just no good? I will try that test later today and see what i find out.
Thanks,
Jeff
Thanks,
Jeff
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Joined: Dec 2000
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From: Nebraska Farm
oil guage
There is a difference in senders. The gauge sender is bigger, about 1-1/2" tall and round. The idiot light sender is pretty small, it just looks like a nut with a screw sticking out the top. If the engine came out of a truck with a light, it probably has that sender. Its mounted down where the oil filter screw on.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.
Thread Starter
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Senior User
Joined: Jan 2000
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From: Mount Sunapee, NH
oil guage
I know the engine is a '67 390 out of a car, not sure what model car though. Do you think back in '67 they would have idiot lights?
Jeff
Jeff
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From: Racine WI
oil guage
depending on what model car and what options it had, yea they had idiot lights in 1967
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oil guage
I agree with sparky. I had a gauge sending unit in an idiot light equipped truck and the behavior was the inverse of yours. No light with the engine off and key on, but as the engine built oil pressure the sending unit would cause the light to come on.
