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Matching oil temp and pressure gauges. 9 years 6 months ago #149487

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  • mgf mk2 freestyle mpi 16" wheels, in Anthracite.
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Catch 22 situation.
I need to remove the original sensor to measure the thread.
If you remove the sensor the oil pours out.
So I need a plug of the same thread to put in place of the sensor.
I need the original to measure the thread... :bang:
David
:shrug:

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Matching oil temp and pressure gauges. 9 years 6 months ago #149500

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OK I made the assumption that it is M12x1.5 and made up an adapter. The thread on the new sensor was actually 1/8NPT and according to the MGR electronic parts catalogue this should be correct for the car.

Now the new sensor is fitted correctly and this confirms that the thread is M12x1.5

Perhaps the thread was changed at some point?

The meter is now reading well. :woohoo:
David
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Last edit: Post by David Aiketgate.

Matching oil temp and pressure gauges. 9 years 6 months ago #149504

Thanks for that David. Been trying to find out that info for a while now and not being near the car - 350 miles away in fact at the mo - it's been tricky. When I get back home it's a job I intend to do. For those who ask why an oil pressure gauge? To quote Sir Stirling Moss, "the light merely tells you when to buy a new engine!" :hgf:
The pressure sensor on the oil warning light only comes on when the pressure falls below about 10 psi - if of course the sensor is working correctly. It's a pity they're not digital and then you could programme them to come on a little earlier and give you chance to stop before the damage is done!
Cheers John

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Matching oil temp and pressure gauges. 9 years 6 months ago #149526

At least the guage will give you a baseline. Then when you see changes from the norm you can investigate.
When I had my supercharged MG Magnette the oil pressure guage saved my engine, ironically the braided hose to the guage failed on my way to a British Car Show, and the needle dropped like a stone. Unfortunately I was doing 80MPH on the freeway through Seattle Washington at the time. As I was going through a construction zone there was no place to stop and by the time I was able to get off the freeway I had lost 4.5 litres of oil, fortunately with no ill effects. The car stopped 100m from a foreign car repair shop and they were able to get me a replacement hose within 3 hours. I did make it to the event I was going to. :clap:

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Matching oil temp and pressure gauges. 9 years 6 months ago #149538

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Interesting that the sensor thread is the same as the thread on the wheel studs... :dry:

The sensors are definitely shown as 1/8NPT in all the documentation, so I can only assume that the thread was changed at some point. It would be helpful to find out when.
My car is a mk2 2001 so I assume that all cars newer will be M12x1.5.
David
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Matching oil temp and pressure gauges. 9 years 6 months ago #149541

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At least the guage will give you a baseline. Then when you see changes from the norm you can investigate.
When I had my supercharged MG Magnette the oil pressure guage saved my engine, ironically the braided hose to the guage failed on my way to a British Car Show, and the needle dropped like a stone. Unfortunately I was doing 80MPH on the freeway through Seattle Washington at the time. As I was going through a construction zone there was no place to stop and by the time I was able to get off the freeway I had lost 4.5 litres of oil, fortunately with no ill effects. The car stopped 100m from a foreign car repair shop and they were able to get me a replacement hose within 3 hours. I did make it to the event I was going to. :clap:


The last time I had an oil ejection episode it was in the Nissan. The AA man and me couldn't figure out how it had escaped.
But recovered it to my usual garage.
It was my mechanic who pointed out the 50p size hole in the crankcase...Whoops. :slapme:
David
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Oil temp reading too high. 9 years 6 months ago #150985

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After living with these gauges for a while I'm very happy with them.

Two small problems.

1/. Using the oem oil pressure wiring with the new sensor and gauge means that you just need to splice a wire from the feed to the oil light to give a reading for the gauge. The problem is that the oil light glows dimly. Took out the bulb. :yesnod:
2/. The OEM temp sensor is not only M12x1.5 but it has 4 wires coming out of it. :-? This means that I can't swap it for the one that came with the gauge. (Single wire)
So I retained the sensor and used the oem feed to power the new gauge. That works. :yesnod:
Unfortunately, the sensor is giving too high a reading :yesnod: 120 around town, 150 on the motorway. :slapme:
My original gauge read high but not that high. Usually 100 around town, 120 on the motorway.

I thought I would be radical and get the gauge to read more accurately!

I know that some gauges read really high from the factory and the accepted fix was to put in an in-line resistor to reduce the reading.
Apparently a 0.5w 15 ohm resistor was the one used.
The instructions from our friend Dieter's site:-

MGF MY1999 Oil Temperature Indication Failure

Affected cars: MGF Modelyear 99 (the first of the so called MY2000) approximate VIN range 511000 ... 52????, not official approved !!
Failure: Indicator for the oil temperature raises up to 170°C at high speed.
Reason: The dual Oil temperature Sensor does not relate to the specifications

Action:
Pull off the 13 position multiplug No. C160. This plug is located in the engine bay left of the main relay.
Cut the brown-blue wire at app. 60mm apart from the plug
Solder a resistor of 15 Ohm O,5Watt between this open connection and seal it with shrink tube.


Wanting to get a more accurate gauge rather than just reduce the reading, I bought a selection from 10 to 50 ohm from Maplins and prepared to experiment. They only stock 0.6w but that difference is not important.

I visited my friendly MOT garage and established that when the gauge read 130 the oil was actually nearer 95.

So then it was a question of introducing the various resistors until the reading was correct. In the end it was 45ohms that did the job.

Also I reasoned that it was substantially easier to introduce the resistors at the gauge end rather than the quoted above position. So I made up a small adapter to go between the plug and the gauge. I soldered a male and female spade connector to each end of the resistor covered it with shrink tube and Robert's your father's brother.



Then it's just a case of popping out the centre vent and inserting my adapter into the line.
:broon: :woo2:
David
:shrug:
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