Diagnosing Low Oil Pressure

[winemaker]

My oil pressure reads almost nothing at idle and only half of normal (140-150 instead of 275)

A couple questions:

where is the oil pump, within the block?

How would I test to see if it's only the gauge or sender?

If it's the sender, where is it and how do I deal with this?

Thanks in advance: this is a huge concern to me.
Brett

[Robyn]

The easy way to do a test is to install a T fitting in the Oil pressure feed to the turbo and hook up a direct reading gauge.

Are there any other signs of low pressure???

The pump bolts to the rear mainbearing cap and is driven by a little shaft that goes up and connects to the pump drive.
The pump drive sits where a regular chevy distributor would go.

The pump is inside the pan and takes a fair amount of work to get to it.

The Oil pressure switch can be the culprit.

The switch (depending on the year of the rig) is located either in the back behind the LH head on the flange of the block or up in the valley right behind the intake manifold.

Try a T fitting in the turbo line and see what you get. (dont run the engine with the turbo feed line unhooked though)

20 PSI is normal idle. 40 PSI or more is good for higher RPM

The electric senders can and do go south on these trucks.

Keep us posted

Robyn

[winemaker]

Thanks Robyn...I work 6 days a week and may not get to this until Sunday...or next Sunday depending on the demands of family life, but I sure appreciate the direction and I'll keep you posted.
Thanks Again!
Brett

[More Power]

The turbo oil feed line would allow for a good test - just looking for oil pressure, but it'll read lower than it would nearer to/at the oil pressure sender port. By the time the turbo gets its oil, the oil pressure will have already been decreased by feeding all of the lifters, the cam and the crankshaft. As Robyn suggested, always suspect the sender before considering something else.

Jim