High tem at engine

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John Wurner
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High tem at engine

#1 Post by John Wurner »

Recently changed the oil and filter.
Drove the car a distance today and the oil gauge went off the scale, car is a 59 Super.
I used a Mann PF915n oil filter which has very small holes as compared to other filters.
I checked the oil temp with a stick gauge and it was at 175, somewhat normal.
Could it be the filter, gauge or?
Gauges were rebuilt but not guaranteed hooked up correctly. My gas gauge flops to full when the key is turned on
and I have not figured that out either. Tank is not full.
Thanks for any help, John

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David Jones
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Re: High tem at engine

#2 Post by David Jones »

John it is an electrical issue and It is likely caused by the power supply to the gauge. It comes from the ignition switch and is yellow/blue in color. Make sure this wire is still in place in the ignition switch and still plugged in to the back of the combo gauge. It supplies power to the fuel gauge sensor and the oil temp sensor.
If you PM me I can send you a copy of the wiring diagram for the combo instruments.
If I had known I would live this long I would have pushed the envelope a little harder.
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John Wurner
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Re: High tem at engine

#3 Post by John Wurner »

Hi David
I will check that out.
I have Leoni's diagrams but poor electrical skills.
The gauge did not go up all at once but a little at a time. Until she ran out of scale.
Will let you know on progress.
John

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John Brooks
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Re: High tem at engine

#4 Post by John Brooks »

John

Gauges are really pretty simple operation. Zero volts 0V= empty or cold. Six or Twelve volts 6-12V= full or hot. Any voltage between 0 and battery voltage is in between. The battery voltage is applied to the gauge, and then ground to at the sensor. If the sensor is a short the gauge sees battery voltage and goes to max. As the resistance of the sender increases, the gauge voltage drops, the needle drops.

Just look at the voltage at the switch for battery voltage. Then measure the resistance at the temp sender it case. It should start high reading and decrease as the oil warms. Same for the gas gauge, around 200 ohms empty and 0 full.

if it flops to full with the key, sounds like you have the wire reversed on the gauge and it sees ground all the time.

The filter should not change the temp unless you have no oil flow through the filter.
John Brooks

62 Roadster
66 912
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getting pushed around in porsches since 1965

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