Monsoon 335 High Oil Pressure

[Tidbury]

Looking for some suggestions before I go through the headache of pulling the motor. I have a 2003 Malibu Response LXI with the Monsoon 335. I have never had any oil pressure issues until about half way through this season. The oil pressure used to read around 40psi at idle and climb to maybe 60psi at 34 mph. This year the idle psi is closer to 60 and if I take the boat to 3500 rpm for more than a couple of seconds the pressure climbs to 80 and the alarm goes off. So far I have changed the oil filter, pressure switch and the pressure sensor. The readings are staying the same and the alarm goes off at 34mph. Any suggestions for what else I can look for? From searching on line it sounds like it might be the check valve in the oil pan.

[Jody_Seal]

scan it with diacom and see if the scan matches the gauge. also install temp mechanical gauge and check.

 

[buechsr]

I recall that there is the alarm and pressure sensor on a monsoon of that era, but you've changed both. Every oil pressure issue I've heard of has been resolved with one of those changes.

 

Might be a waste, but easier that pulling engine and dropping the pan, have you changed the oil? Why not change it, run a very thin oil, with a quart of marvel for a few hours, change back to 15-40 to see if that break down any obstruction?

 

Diacom if possible too.

 

I've never seen this product before but would allow you to verify your readings?

https://www.amazon.com/GearWrench-3289-Oil-Pressure-Tester/dp/B0002SQWY8/ref=asc_df_B0002SQWY8/?tag=hyprod-20&linkCode=df0&hvadid=312280085431&hvpos=&hvnetw=g&hvrand=16371801770507433362&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1015141&hvtargid=pla-558028671535&psc=1

 

[DW]

A check valve tends to trip at a certain pressure so one would expect your idle pressure to have remained constant rather than an upward shift, and only the higher speed pressure to have changed. Seems more like a signal issue from the sensor or there is molasses in the oil pan. Jody is pointing you in the right direction, an alternate pressure reading.

[LeonL]

Get you a mechanical gauge for test purposes.

[Vernon Reeve]

It's also possible the new pressure switch and/or pressure sensor are bad. I've had something like this happen where I installed the new part with no success, so hired a mechanic, who found the new part was bad:(

[hemlock]

Try cleaning your canon plug. It's on the starboard side near the rear. It has several connections in the plug so take note in which orientation you pull it out. Disable your battery first. I used a spray can of connector cleaner on mine to help my oil pressure issue which was the opposite... it went to zero at random times.

[Tidbury]

Thank you for the replies. I am picking up a mechanical gauge this weekend to see if the pressure is indeed what it is showing at the gauge. Trying to get my hands on a diacom too but I may need to get to a dealer for that. I will also try the canon plug. Hopefully it is something relatively easy to diagnose / fix.