Low oil pressure at idle

[Ian1959]

Hi Everyone,
I have a Daimler 2.5 V8 which has recently developed an oil pressure problem at idle once normal working temperature has been reached. I have verified the readings by replacing the pressure sender unit with a pressure gauge and they range from 45 psi at 3000 rpm, dropping to 35 psi at 2000rpm and 8 psi at idle. The workshop manual suggests 35-45psi for normal running and 20 psi at idle. Has anybody else experienced this problem and what can cause low oil pressure at idle and correct oil pressure at normal running?

Many Thanks

Ian

[piman]

Hello Ian,

a little strange but it's the running pressure that is important. It will not do any harm to do an oil and filter change and see waht it is like after (Using a 20/50 multigrade oil, not a modern low viscosity oil)

Alec

[Ian1959]

Thanks Alec,
These are the results after fresh 20-50 and new oil filter. I cannot hear any knocking from the big or little ends. Can this effect be caused by a worn oil pump? I am I worrying unnecessarily, since as you say its the pressure at normal running speed that matters?

Ian

[piman]

Hello Ian,

in that case it's rather puzzling. If your oil pressure is as specified at 3,000 rpm with the engine hot I don't think there is much to worry about?

Alec

[Ian1959]

Hello Alec,
Thanks for your help. I am going to monitor the oil pressure and see what happens.

Ian