I recently changed the engine oil and filter in my Westerbeke diesel. I gave it the usual (and specified) 4.5 quarts of SAE 30, specifically Chevron DELO.

Now when it starts up it reads 80 psi of pressure (it might be more -- that's the maximum value on the gauge) instead of the expected 15 to 50 (idling to fully loaded -- it usually sits at 40). Oil level is correct according to the dip stick.

The order of the components in the lubrication system are:

  1. Sump
  2. Screen
  3. Pump
  4. Fuel pump drive gear
  5. Release valve
  6. Crankcase gallery
  7. Filter
  8. Pressure gauge and sender
  9. Oil cooler
  10. Main gallery
  11. Bearings and cylinder bores
  12. Cylinder head and rockers
  13. Return

I thought for a moment that the new filter might be bad, but given that the pressure gauge is downstream of it I don't think that could be the problem.

I have never encountered this problem before. Ideas on what might be causing this and how to troubleshoot it? Any help with this would be greatly appreciated!

1 Answer 1


Does the gauge ever read less than maximum? If not, I would suspect a bad gauge or sender.

EDIT to follow-up on comments: check for a kink or other problem in the wire. The wire from my oil temperature sender passes over a piece of plastic sticking up from the drip tray. Over time, I lost one wire to relentless wear - rubbing clean through the insulation at one point.

If it's a wiring problem, it's not impossible to fix. It may, however, be inconvenient to fix well....

  • I would agree with Bob.. if the level is correct and you're sure the weight of the oil is correct, I'm thinking sender/gauge.
    – NoCarrier
    Mar 15, 2011 at 22:42
  • The gauge sits right at the maximum value. I'll see if I can find a replacement gauge and swap it out. I wish I had a flow gauge.
    – Justin R.
    Mar 16, 2011 at 0:52
  • 1
    @fatcat1111, considering that you're seeing an oil pressure that is at least twice what you're used to, the oil weight doesn't sound like a viable candidate. If it dropped down to something more like what you expected after running for a while, that might be different.
    – Bob Cross
    Mar 16, 2011 at 10:20
  • 3
    Turns out it was the wiring to the sender. I bought an engine oil pressure testing device ($10 at Harbor Freight), swapped it in, and fired the Westerbeke up. It showed perfect pressure. Examining the sender that was on there, I found that the lead was down to two strands of wire! I suppose thirty eight years of vibration eventually wore it down, and I must have bumped it when I was changing the filter. Snipped the end off the wire, attached a new ring connector, reinstalled it and it works again. Thanks all!
    – Justin R.
    Mar 20, 2011 at 1:20
  • 1
    @fatcat1111, Congrats! Don't you love it when the problem is solvable?
    – Bob Cross
    Mar 20, 2011 at 1:26

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