Conflicting readings between oil pressure gauge and oil warning light.
Turbo Mini Forums

I seem to have a bit of a weird oil pressure issue with the twin cam.

It only came to light when fitting a 20psi warning switch, for a bit of added safety margin.

The oil pressure gauge is indicating 40psi at hot idle @70 degrees celcius. Yet the oil light is just being tickled. any revs and the pressure picks up and the light is not being tickled.

I fitted a new stack oil pressure gauge to validate that is accurate. The take off for the head, switch and gauge are all taken from the main gallery/original switch location.

I have removed it from the car and hooked up to the air line and oil pressure gauge and it does seem to be activating at 20 psi. Tried pouring a kettle of boiling water on it too to see if that made any difference to try to mimic when the oil is hot.

I can therefore only assume there is an issue. Whether that be pulling air in from somewhere or the oil pressure relif valve getting sticky, though freed this off tonight and have yet to test.

Any thoughts on the matter?

I feel a precactionary engine out job may be in order.

I have had this same issue but not on a twin cam. and i find oil pressure switches to be a sensitive crowd they are not simple on off devices and their operation can hunt between values. When the whole situation is controlled by the ecu the ecu triggers the light, but then you have no idea as to the actual oil pressure do you. With a gauge fitted you can verify the function of the switch, I would not verify the function or reading of a gauge using a switch. The one thing I would say is that my oil pressure gauge sits at 50psi hot or cold at idle. So you may be within that hunting range of that particular switch, which means this may be indicative of another issue.

Own the day

Thats informative.

As a starting point I shall try a different brand of switch, then go from there.

Regards

James

Ask yourself what parasitic losses you have in your system. You have the turbo for one and the under crown oil jets. How good are the clearances on the crank journals and the cam shafts?

Like I said I had a similar problem which forced me to pull the engine, oil pressure dropped significantly on idle to about 20psi turned out a mains bearing had lost chunks of material luckily no further damage was done.

And just to add my oil light did not come on!

Edited by Mr Joshua on 27th Mar, 2024.

Own the day

On 21st Mar, 2024 minimole23 said:
I seem to have a bit of a weird oil pressure issue with the twin cam.

It only came to light when fitting a 20psi warning switch, for a bit of added safety margin.

The oil pressure gauge is indicating 40psi at hot idle @70 degrees celcius. Yet the oil light is just being tickled. any revs and the pressure picks up and the light is not being tickled.

I fitted a new stack oil pressure gauge to validate that is accurate. The take off for the head, switch and gauge are all taken from the main gallery/original switch location.

I have removed it from the car and hooked up to the air line and oil pressure gauge and it does seem to be activating at 20 psi. Tried pouring a kettle of boiling water on it too to see if that made any difference to try to mimic when the oil is hot.

I can therefore only assume there is an issue. Whether that be pulling air in from somewhere or the oil pressure relif valve getting sticky, though freed this off tonight and have yet to test.

Any thoughts on the matter?

I feel a precactionary engine out job may be in order.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I changed to a MOCAL sender, which has not yet illuminated. That said I have not had the oil temps right up beyond 80 ish yet.

Tried 2 pressure gauges both reading the same.

Pulled a cam cap off and the head- i.e. the furthest point in the oiling system, and that is getting well oiled.

Also cracked a union off the oil cooler to see if there was some sort of airlock, also doesn't appear to be the case.

I did notice air pockets in the capillary line to the pressure gauge though which makes me wonder if its pulling some in somehow.

It seems Oil pressure has always been slow to build regardless of engine, with the oil cooler installed vertically, so may look to revise this later in the year to see if that makes a difference.

I ditched the oil pressure switch as the accuracy for such a cheaply mass manufacturerd item isn't worth it. I have an oil pressure sensor into the ECU and would rather trust that.