no oil pressure when warm

[tvrimp]

hi guys
i have a problem with oil pressure on my S3 after a couble of mins of running the oil pressure drops off to zero during the warm up the pressure is all over the place then settles at about 50 then drops to zero.i have replaced oil and filter.
would i be correct in assuming its sender unit.or is it worn big ends i am not getting any knocking etc.

[tvrgit]

best thing is to try a capillary gauge on it, to read the real oil pressure independent of sender etc. it might be the gauge or sender but you must be sure that it isn't a real drop in pressure which renders the car undriveable till it's fixed.

[Le TVR]

Quick check:

Can you measure a voltage at the sensor terminal?
If yes, disconnect wire from sensor and measure the resistance between the terminal and ground. (IIRC should be less that 500 ohm)

No voltage - check gauge and wiring
No resistance - check sensor
Volts + resistance OK - check engine

Suspect the wiring first (it is a TVR after all.....)

[foxy600]

These are exactly the same symptoms I had last year, not sure if you read my posts but mine ended up being the big end, I would highly recommend getting this checked out ASAP...sorry to be mr. doom & gloom!

[tvrimp]

thanks tvrgit removed sender and fitted gauge i purchased from local auto shop £9.95 seems all is well with engine pressure sits at about 25psi at tickover and rises to 50+psi at 3500rpm.must be the sender unit.
i have spoke to david gerald they have one in stock £49inc p+p oh well cheaper than replacing the big ends.
once again thanks for help.

[tvrgit]

tvrimp said:

thanks tvrgit removed sender and fitted gauge i purchased from local auto shop £9.95 seems all is well with engine pressure sits at about 25psi at tickover and rises to 50+psi at 3500rpm.must be the sender unit. i have spoke to david gerald they have one in stock £49inc p+p oh well cheaper than replacing the big ends. once again thanks for help.

no problem

I would also check leTVR's suggestions of wiring between the sender and the gauge first