View Full Version : warm oil pressure causing alarm

07-21-2006, 02:42 PM
I posted a thread recently about an intermittent alarm from my ignition that was very persistent. Was out this morning and playing around with things I noticed this alarm went away if I put boat in neutral and increased RPM. Oil pressure shoots up to 45 and alarm goes off. As I return to idle and pressure drops to 15 to 20, the annoying buzzer starts up again. I now believe this persistent alarm is in fact trying to warn me about low oil pressure. Engine has 238 hours on it (1988PS190). I just purchased that boat and am not sure what viscosity is in it. Thinking I will change tonight and go thicker. Should I jump up to straight 40 wt? Straight 50W? Will thicker oil solve the problem. Has anyone used viscosity to resolve this issue?

07-21-2006, 03:11 PM
I would change the oil + filter but do not use 50w, use what the manufacture recommends. is there sludge build up inside the oil filler cap, dip stick etc ?

20psi doesn't sound too bad at idle with a warm engine.

238hrs is not high but 238 hrs would be a lot if the oil has never been changed.

any strange noises from the lifters etc ?

you might think about putting a oil pressure gauge directly on the engine to get a better idea of the pressures, I find dash gauges can be off some what.

dirty [sledge] oil pump pickup screen can cause the symptoms you describe.

seems like I remember something about oil pump drives being a issue on some MC models.

there's lots of internal $$ stuff that can cause low OP also.


07-21-2006, 03:16 PM
Service records would indicate frequent oil changes, more based on seasons than hours. Oil on dip is clean as a whistle. No other supporting indications of a weak or damaged internals. I like higher oil pressure, but have never been too considered about low oil pressure when warm and idling. My 1988 manual recommends 15W40, but I don't think that will change oil pressure.

The guage bounces around a lot at idle as weel, but I've thought that was probably a ground issue as other guages do the same, until RPM increases. Input?

07-21-2006, 05:02 PM
If your gauges are bouncing around at low idle and get solid with higher rpm, I would suspect loose wiring, corroded connections, low battery voltage.....
Your engine alarm is more likely because of the low voltage.
Second I would check your engine temperature. You may be getting low water flow at low rpm.
My oil pressure gauge does the same as your's and it is fine.

07-21-2006, 07:22 PM
Temp (according to gage) is fine, around 160/165. I'll have to go over all wires, and ensure tightness. Any predictions of how much oil pressure bump an engine gets when chaning from 30W to 15W40?

07-21-2006, 09:39 PM
CW, i've got an 87 that had the same issue. Likely your oil pressure sending unit is bad. Replace it and you should be good to go. Also, i've used 20w50 in mine for the past ~5 years...no issues.

07-22-2006, 06:35 PM
Thanks man. I changed oil today, 15W40 with STP additive. I think I'll run it once and if probelm persists I'll replace sending unit next. Will let you know.