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GOOD NEWS: easy fix for low oil pressure - Engine/Ancilliaries - The Lotus Forums #ForTheOwners Jump to content


GOOD NEWS: easy fix for low oil pressure


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Corrosion on the spade of the oil pressure sensor can give an alarmingly low (and wholly false) oil pressure reading on the oil pressure gauge.

On my 1997 V8, the pressure sensor lies about 2 cm away from the cast iron turbocharger housing. The sensor is next to the boss where the oil filter threads to and can be easily removed with a 16 mm wrench. Likely the extreme heat cyles of the turbo speed up corrosion rates of the sensor terminal and supply wire. My sensor was pretty much uniformly rust covered (it appears to have been cad-plated when new) plus the spade connection was "fluffy" with white corrosion. I chose to cut off the crimped-on wire connection and replace it with a new one (crimped and then soldered on for good measure). I also sanded the spade terminal of the sensor.

This dramatically changed the reading on the oil pressure gauge . . . from about 0.5 bar at idle (before cleaning) to slightly more than 3.0 bar at idle (post cleaning). Good news because low engine oil pressure is rather alarming and this is such an easy fix!

I also noticed that Lotus left quite a lot of extra wire to the sensor switch. If loose and un-fastened (like mine was), it is possible this wire could touch the turbo where it almost cetainly would melt/short out. I looped it around the sensor once and zip-tied it well away from the turbocharger.

Hopefully this info will help a concerned owner.

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Interesting! Every one I've seen broken or corroded has given a HIGH pressure reading...

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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I agree....usually a gauge is nothing more than a glorified ohm meter with a short resulting in minimum reading and open resulting in full or high reading. Having corroded connections should increase resistance, making the gauge read incorrectly high. Having said this, I'd suggest testing with a mechanical gauge to verify your 3 bar oil reading to ensure that is in fact correct and not possibly additional wiring issues given the close proximity to the turbo housing as you mentioned.

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Corrosion on the spade of the oil pressure sensor can give an alarmingly low (and wholly false) oil pressure reading on the oil pressure gauge.

On my 1997 V8, the pressure sensor lies about 2 cm away from the cast iron turbocharger housing. The sensor is next to the boss where the oil filter threads to and can be easily removed with a 16 mm wrench. Likely the extreme heat cyles of the turbo speed up corrosion rates of the sensor terminal and supply wire. My sensor was pretty much uniformly rust covered (it appears to have been cad-plated when new) plus the spade connection was "fluffy" with white corrosion. I chose to cut off the crimped-on wire connection and replace it with a new one (crimped and then soldered on for good measure). I also sanded the spade terminal of the sensor.

This dramatically changed the reading on the oil pressure gauge . . . from about 0.5 bar at idle (before cleaning) to slightly more than 3.0 bar at idle (post cleaning). Good news because low engine oil pressure is rather alarming and this is such an easy fix!

I also noticed that Lotus left quite a lot of extra wire to the sensor switch. If loose and un-fastened (like mine was), it is possible this wire could touch the turbo where it almost cetainly would melt/short out. I looped it around the sensor once and zip-tied it well away from the turbocharger.

Hopefully this info will help a concerned owner.

I finally bought my Lotus after promising myself one for 30 years! The one I bought has low oil pressure indication (no other symptoms like smoke, water on the dipstick an it's done a few hundred miles with a reading of about 0.5 bar) and when I finally found the sender the terminal was fairly clean. I cleaned it anyway with no difference to the reading. Does anyone know what the resistance should be from the sender spade conector through the gauge to ground? How can I test the sender without removing it? If I remove the sender to insert a mechanical gauge, how much oil will I lose?

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to verify the reading of the big '97 instrumental dial-gage sender on the oil filter adapter -just use the port for the normal oil-pressure switch on the side of the engine block. You could try to install an manual dial gage in the same time and look what it shows whilst the engine is running. The small oil-pressure switch in the block is there for the oil-pressure light/control normally.

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