The Lotus Grand Tourers

Just taken the car for a run (had to jump start it) and after 2miles, 1 on a motorway I noticed the oil pressure gauge reading off the scale. Coolant temp is spot on with no problems .I eased off the gas to tickover revs and the pressure gauge is reading 3.5 bar. The moment I touch the accelerator its up past 5 and off the scale. Engine sounds and drives fine . Any sugestions as to where to start. Gauge, sender or expensive problems!!!!

start by swapping out the pressure sender and/or gague... it'll probably b one or the other...

Pressure will be related to flow.

If you have a restriction it could 'possibly' show as high back pressure on the gauge.

I'd try an oil flush and system clean and then new oil and filter, and not too many miles 'till I was sure what was going on.

Oh, and not forgetting that some residue of flushing oil will remain in cooler. I'd use a cheap oil to flush the 'flush' after the flush......

If that makes sense.

If the sender wire comes off or loose (usually at the engine end) the gauge will default to maximum pressure (off the scale).

Bit more info. I ran it up to temperature this morning. The oil pressure needle sat at 4.5 on idle but would go higher if I raised the rev s to 3000ish and then return to 4.5 once off the gas. Once it then jumped over past 5 into the red. However on turning off the engine it didnt just drop to 0 it dropped to 2.5 they bit by bit over 3 seconds and stopped at .5 until I turned the ignition fully off when it went to 0. Now I cant remember what it would do normaly as normaly I just turn straight off. Would this sugest the slight blockage sugested by DPR59. It only had an oil change 3K ago so dont want to waste the oil but better that than new engine.
And it was all going so well

Thanks for all the replys guys.

Ive taken the wire off the sender and the gauge went straight round past the red section and off until it hit the stop. That was further than it went when it was running. I noticed it also sat at .5 before the engine started. I ran it for a minute then turned it off but left the ignition on. The gauge dropped to 2 then slowly dropped or even flickered up and down eventualy stopping at .5 . I guess I need to pick either the gauge or sender and swap it to see.
Any ideas where the sender is from?

As always......

Mike Tayloe, Lotus Bits is a good place to make the first call to.

The answer is to temporarily fit a mechanical gauge to the take-off point on the engine.. Then you can get a reliable reading that will tell you if the dashboard gauge is telling porkies. My money is on a dodgy sender unit.

PS my '88 MY car always goes off scale when revved. I was told by an experienced Lotus mechanic at Motorway Sports Cars that when Lotus changed from the five bar gauge to the seven bar version on the later cars, some cars were inadvertantly made with the five bar gauge fitted instead of the seven bar. I have run the car for over ten years like this, with no ill effects. I ought to fit a seven bar gauge (if I can find one!), but I imagine its one of those things I'll never get around to doing. There's always something more important to do.

Im going to start with the pressure sensor first. It was fairly tight but came out with a bit of effort. Now to find a new one.

All sorted now. I fitted a new VDO sensor £32.47 inc vat. Nice smooth movement to the gauge now. Tick over when warm 1.6 at 3500 rpm its 4. I had to remove the whole air filter box and the starter to make access easier but it all went ok.