Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing +8 oil pressure

Hello dear friends,

A question, concerning the correct oil pressure of a 3,9 liter engine. When a warm, my pressure gauge, reads 3 to 4 bar on idle and up to 5 bar (75,2 PSI) when under load. Is that OK, or should I worry?

To my shame, I’m not sure if this was the case since I have the car, but I think, that the gauge never went that far right.

Thanks for your replies.

Sunny greetings from Luxembourg,
Ivo

The v8 is a low pressure high flow engine. Your figures sound very high.

I’ve had several cars with this engine and pressures have always been 2-3 bar running and 1-2 bar at idle. Hot. Occasionally lower with no problems

Gary

Mine is as Grumpy2 has described - sometimes in mid summer I have seen 1 Bar at tick over.

4 Bar is the highest indication I have seen when cruising at speed. My 1994 3.9Ltr had the same indications as my present one so I have assumed that is normal.

If everything is ok with the engine I wouldn't worry too much about it, it could be a faulty gauge, any garage can check the actual pressure if you have concerns.
I'm assuming the oil and water levels are normal and no signs of any oil gaskets weeping on the engine.
Good luck with it Ivo.

Mine regularly reads 3.5 bar at idle, 4.5- 5 under load at speed, and occasionally drops to 1.5 at idle after prolonged (3+hrs) use. Its read like this since I've had it over the last 15 months. Runs well, so could be a characteristic of my particular gauge. If your regular with oil changes and there's no discernable faults, I wouldn't worry too much. A marked change from the "norm" would worry me more.

Thank you very much. The car is due for service anyway, so i‘ll let the garage have an eye on it.

Sounds a bit high for a Rover +8 .could be gauge fault.

My gauge started going haywire about 4 years ago. After a few miles reading ok it went up off the scale.
It was a faulty oil pressure sender. The car is a 2002 4litre with Gems management and if the pressure is lost it cuts power to the fuel pump to stop the engine. There is a switch on the oil pump housing that will do this. The faulty sender was just for the gauge and replacing it put things back to normal. This sender for the gauge only and is accessed under the car driver’s side towards the rear of the engine. Simply disconnect the wiring, unscrew it and replace. There was no actual oil pressure loss as that would have cut the engine.
Have a look at Gomog and Plus8 specific section.

https://www.gomog.com/allmorgan/plus8index.html

Thanks for the info Sospan, I've the same vintage so good to know 👍

As Sospan and others have pointed out the gauge is electrically connected to a sensor , so a reading is dependent upon the quality of the electrical circuit. On my Hotwire system there is no feedback loop to the ecu, but the connector to the sensor is still the weak point.

Once hot, my 1998 car generally idles at about 2/3 bar , and will normally run at about 4/5 at cruising revs. After a Malory Park MSCC track day I noticed the pressure was almost off the scale at any RPM. On checking the connection to the sensor had worked loose , tightening it up put things back to the above figures immediately.

These figures are only applicable to the later "serpentine belt" Rover V8s , the early versions were high capacity oil systems , not high pressure.
A dealer once told me "as long as it has some oil pressure on the gauge it is probably OK" . Must admit that would still be slightly worrying for me to accept.

So why don’t we all worry about our tintops which merely have an oil light to warn us of low oil or pressure. Think all these gauges are nice to look at and “set the scene” but sometimes maybe it’s a case of “too much information”?