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Join Date: Jan 2018
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Oil pressure gauge issue.
My oil pressure gauge reads half way with the ignition on.
Where do I start to look ?? Engine has been rebuilt and fitted. Can't start as I'm waiting on a new cooler. Any pointers would great. I don't believe it's done this before. I just had an issue with light switch which is now fixed . ( Maybe connected ?? ) Lyndon 
Last edited by Lyndon302; 11-02-2021 at 07:20 PM.. |
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11-02-2021, 07:16 PM
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Reiver
Join Date: Nov 2011
Posts: 57,406
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Bad ground...take it out and clean all of the connectors
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11-02-2021, 07:36 PM
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Quote:
Lyndon |
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11-02-2021, 07:38 PM
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It's a 914 ...
Join Date: Jan 2008
Location: Ossining, NY
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Since the motor was out, I'd look first as the connections on the sender and as suggested make sure you have good ground. Did you refit the ground strap when the motor/trans assembly went back in? Did you need to put a new sender or mess with the wiring to get the oil light working?
Can't hurt to check connections on the gauge too, but I'd look at the stuff that was disassembled first. |
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11-03-2021, 04:20 AM
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Reiver
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Quote:
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11-03-2021, 08:05 AM
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Location: Boulder, Colorado
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It can also be a signal line resistance issue: The gauge has +12V, ground, and signal. If the 12V connection, and the gauge ground connection is good, then what the gauge does when the key is turned to run is controlled by the resistance to ground on the signal wire. High resistance means the gauge needle is high. The ultimate high resistance comes by disconnecting either end of the signal wire, which pegs the gauge.
The sender starts out, at 0 pressure, with a low resistance. As the pressure increases, so does the resistance. If, as suggested, your engine ground has some resistance in it, the gauge will act like this. If the signal wire connectors at either end (sensor or gauge) have some resistance, you could get this. The most common cause of the gauge pegging is for the sensor wire to come off of the sensor. Next is for the resistance wire in the sensor to wear through at some point, so the oil pressure readings are normal up to a certain value, and they (after the break) they peg. Neither of these seem to fit your less common problem. |
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11-03-2021, 02:59 PM
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Ok
Remove the wire off the sensor on the engine. Nothing different. Remove the black and green wire off the back of the gauge and it goes all the way up. ( Needs a little tap on the glass to get it to fall back down ) Am I correct. Wire off nothing. Earthed it goes to full. Thanks lyndon |
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11-03-2021, 03:00 PM
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Reiver
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Bad ground
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11-03-2021, 03:53 PM
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They are playing up now. Will have a dog around when I get home Thanks lyndon |
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11-03-2021, 03:58 PM
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Reiver
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11-03-2021, 05:07 PM
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11-03-2021, 05:34 PM
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Sorted I think.
Wire off the sender it reads half. Wire off the back of the gauge it reads full. ( This should be the same it's just one wire ) So with the wire on the gauge. Sender wire off. I pulled all the wires off my starter relay. Gauge is now full. 😀 So where they all join around the starter I have got it wrong. Its back feeding thru my starter relay. I will get it on the hoist and fix it. Thanks for all the advice. Lyndon 
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11-03-2021, 08:49 PM
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Fixed
My bad. That is how much the stater wire reads when connected. Thanks for the input. Lyndon |
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11-04-2021, 05:56 PM
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