I’m looking for technical help or recommendations on: Oil Pressure Gauge
I have always believed the oil pressure gauge in the NCs to be a dummy gauge which gives a “theoretical” oil pressure calculated from engine rpm and coolant temp…until this evening!
I performed an oil change on my NC. Drained old oil, replaced oil filter and refilled with new oil. Checked for oil leaks before starting the engine… this is the strange part…
I was surprised by how long the “fake” gauge needle to move off its rest after the engine started. It took a good 2 seconds or so before it moved. Similar behaviour to the a “real” gauge which takes a few seconds for pressure to build up after an oil change.
I am going to time how long it takes to move off its perch tomorrow during a cold start to see if it was just my imagination.
My question is…am I correct in believing it is a “fake” gauge or have just fallen into believing it because I read it on the internet and then I keep repeating it, dogmatically.
Is there a definitive source for this “fake” oil pressure gauge theory. I am curious to know the origins.
What’s the question? Truth? The oil pressure gauge on the NC does not display actual oil pressure. Myth? It’s not useless, if oil pressure drops to zero, the gauge will also drop to zero.
Thanks Robbie, you have helped answer the question. The gauge must also take a signal from the oil pressure switch, as well as the engine rpm and coolant temp. But the signal from the oil pressure switch is a binary yes or no.
The reason I detected longer than usual pause before the needle moved is because there genuinely was no oil pressure for a couple of seconds during the first start after the oil change.
It is fake. There is no sender unit for Op on the engine. The one that is there on the filter housing doesn’t do anything either, if you unplug it or the engine runs out of oil no light is illuminated.
You can be as pedantic as you like, but when you’re sat on the hard shoulder with your pistons 1/4 of a mile away in lane 3 you’ll be wondering w-tf happened.
I wasn’t arguing about the fake oil pressure gauge what i was picking you up on was your comment on disconnecting the oil pressure switch
If you don’t know how an oil pressure switch works that’s your issue not mine
Because disconnecting an oil pressure switch will not put a light on or make the gauge go up or down
You have to earth the wire out to put the light on or make the gauge work as all the switch does is earths the wire creating a circuit and putting the light/gauge on when in a low oil pressure situation, generally below 4psi which is generally to late anyway.
You’re completely missing the point. Nobody is the slightest bit interested in how this thing works. Some of us just know it doesn’t, it’s useless. It’s a complete waste of time and money therefore you wonder why Ford and Mazda actually fitted it to all iterations of this engine.
because it costs 3-5 quid retail vs 50-70 for an actual pressure transducer.
I believe they were with the idea if you keep oil levels correct the engine should work fine without one and all that fancy dancing of the needle is to keep the unaware vehicle operator happy that things are happening when you press the throttle pedal.
The first sports car I owned was 1962 technology and had an oil pressure gauge. No fancy electronic gizmos - just simple engineering.
When did it all go wrong?
You’re still missing the point.
Why fit something which is utterly useless?
Add up the cost of:
The pressure switch, wiring and plug.
The extra metal to form the housing, the time and tooling to make it fit the casting, the time to fit it.
It will have been peanuts, lets say £5 per engine.
Now go take that number and multiply it by the number of MZR/Duratec engines built, come back with a total and tell me why they threw that amount of money in the bin.
No
I know the gauge is fantasy in as much as it’s not true oil pressure readings again I’m not arguing that point with you at all
But you were the one who brought up the Switch on the filter housing not doing anything not me, so you steered this in a different direction yourself
You wrongly associated the oil pressure switch on the filter with the gauge as doing nothing it’s for the oil light only operation
EDIT, the gauge acts as if it was an oil light in operation
sorry i should have been clearer to others .
I was just correcting a misleading post just in case others read it and assume it does nothing
Again, I’m talking about the oil pressure switch for the light operation that you brought up Not the gauge as a pressure reading device.
Have a good day hope this clears my post up for you.
I’m going to review an old post because I’m bored on a Friday night.
I’ve accidentally ran the car without any oil, yes ACCIDENTALLY, whilst on jack stands doing an oil change and replacing a speed sensor. Whilst it was draining I cracked on with the job, plugged everything back in, turned it on to see of the light would go out on the dash, it did. The oil gauge was also working fine, revd the ■■■■■■■ a few times and it stalled. To my horror, I remembered it had no oil. No warning, nothing.
P.S. yes, I’m rebuilding it the engine soon because now it drinks oil.
I have a hand written ‘DO NOT START’ sign that I put under the wiper blades as an ‘aid de memoire’ for occasions such as this. We all think we are in control but---------!!!
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Running it with no oil doesn’t cause it to use oil.
Regardless of which it’s now buggered so it’ll give you something to do to prevent you getting bored.
Doing something silly once is acceptable, just don’t do it again because then you have to question your sanity.
That aside, did it rattle much? There are some great vids on YT of people who purposely ran cars without oil in them to see how long they went for. I don’t think I have the complete lack of mechanical sympathy to do such a thing, but they make for interesting watching, if only to see how long an engine can go without oil - which is a surprising amount of time with no load.
