[Nick Gibson]

Hi Guys

After Decembers’ long holiday is gone, it was the first time I could take my Pajero out on the open road for a distance longer than 100km. I noticed an excessive oil pressure reading on my MadMan EMS2 unit fitted to my vehicle.

Often when driving (esp when overtaking) the pressure exceeds 800kPa or 8 bar (to which my alarm is set) which seems quite high. The service manual says that the pressure should be between 2.94 and 6.86 bar at 3500 r/min and above 0.29 bar at idle or 700r/min. At 3500 r/min mine read in the area of 7.5 bar.

I phoned Mitsubishi, and they say that it is fine running at those pressures, however I am worried of popping an oil filter or blowing an oil seal somewhere on the motor. I also enquired if a pressure relief valve is stuck closed, and the mechanic said the pressure would always read very high then?!?

I have also just changed my oil filter (GUD) and oil as I thought it could be a blocked oil filter, and the values dropped slightly. I have also put in Castrol EDGE 5W-40 (specified by Castrol technical helpline)& which is a fully synthetic oil, hoped it would help.(There is no Caltex DELO 400 anywhere near me! )

Any suggestions would be valued! Also is there anyone else who constantly monitors their engine oil pressure as I do so that I can compare?

[RoelfleRoux]

Nick,

Interesting "problem" to have. Not bad for and oldish motor to still run at those high pressures.

Where does the unit pick up the oil pressure and I wonder what a genuine Mitsu filter would do to the pressure?

My indi once fitted a GUD on his Audi and the oil pressure light came on (on low pressure I presume) - the car "insisted" on a genuine Audi filter.

I have a Heynes manual at home - I'll see if I can find something there.

Roelf

[4ePajero]

How sure are you about the accuracy of the Madman gauge?

Take it to a workshop who can fit a (temporary) accurate gauge to the engine to check.

[Nick Gibson]

The engine was apparently overhaulled in Jan 2011, not sure if that has anyting to do with the high oil pressure readings (Much higher when cold in morning...)

I have a 10bar VDO oil pressure sender fitted into a brass "tee" to the oil filter housing on the side of the motor, which I think is before the oil filter (where the OEM oil switch is fitted, and is still fitted).

Accuracy might be iffy or maybe pressure sender is not reading accurately but will have to check at a garage, however all the other values are accurate, temp, autobox temp, volts... It is manufactured be MGL avionics company in Somerset west (they make the EGT meters every one seems to be using in their Pajeros), and is retailed by MadMan in Jo'burg. I would hope their instuments would be accurate and realaible for use in aircraft.

Will revert with pressure results.

[RoelfleRoux]

Nick,

My Heynes service manual agrees with your manual's specs.

The reading you get is less than 10% over the spec. I'm pretty sure the components (you are concerned about) should be designed with a healthier margin than 10%

However

I question the logic that a stuck pressure relief valve will result in a constant high pressure. Surely an increase in pump speed results in an increase in pressure. The pressure pushes the relief piston up against the spring. At lower pressures, the piston isn't relieving any pressure. Only when the pressure gets so high that it exceeds the force of the spring, will the piston be pushed far enough to get to the relief position.