Oil/temp alarm

[Mefish1047]

I have an ‘82 Catalina 30 with an 18HP Universal M3-20. Recently, when I run the engine, my Oil/temp alarm starts to faintly sound after about 10 minutes increasing in volume if I let it run. There is plenty of oil and putting an infrared thermometer throughout the engine it never reads over 160F (gauge reads 140F which coincides with the temp at the case of the sender). Any ideas?

Rey

[Sailmonkey]

What is the oil pressure?

If you can’t answer this and the oil alarm is sounding as the engine warms up, it’s time to get a mechanical gauge and confirm the alarm switch is good.

[Tsuru]

Hello Rey,
Our last boat a 91' Catalina 28 with a M320B had a low oil pressure alarm and high cooling water temperature alarm. Our newer Universal M35B has the same (or at least similar) alarm setup. So I'm wondering if you have a low oil pressure alarm or high temperature?
Either way it's something that needs to be addressed ASAP.
Good luck,
Ray

[Sam Woodbridge]

If what you say is accurate. I would check your wiring harness and be sure you have no bare wires rubbing against something shorting it out. Also I would check your ground wires.

[Compass790]

Originally Posted by Mefish1047

I have an ‘82 Catalina 30 with an 18HP Universal M3-20. Recently, when I run the engine, my Oil/temp alarm starts to faintly sound after about 10 minutes increasing in volume if I let it run. There is plenty of oil and putting an infrared thermometer throughout the engine it never reads over 160F (gauge reads 140F which coincides with the temp at the case of the sender). Any ideas?

Rey

Welcome to CF Mefish.
What post #2 says
The oil gets thinner as it gets hot so oil pressure drops as it warms.
How many hours on that engine? It's not something you can ignore.
After you have checked oil pressure, report back. If you are lucky it may only be worn oil pump or faulty sender.

[FPNC]

Kubota oil pumps will rarely wear out. I've never seen it happen.

Minimum allowed oil pressure at idle is pretty low on a Kubota. About 7 psi is the low limit. The standard oil alarm switch closes at .5 BAR / 7.25 psi.

Typically, the maximum oil pressure is controlled using a ball and spring release valve that is located at the oil filter mount base. This valve opens at high pressure and dumps oil back into the pan. Remove the oil filter and you should be able to see the ball in the seat at about 4 o'clock relative to the threaded stub. The spring is behind this ball. If this pressure release valve has trash in the seat and the ball is not seating and sealing correctly, you will see low oil pressure at lower RPMs. The problem will get worse as the oil heats up and gets thinner.

Remove the valve and clean it. The threaded stub must be removed to access the valve. Or you can try pushing the ball back and spraying some brake cleaner in there to remove any trash. Little slivers of plastic from the neck of an oil bottle seem to be the most common culprit here.

[Cat36Mahalo]

On my early C36 with a M25 I replaced the OP switch with a combo Switch/gauge - on the M25 it only fits if you have the op switch over the trans and not under the exhaust manifold

[Cheechako]

Senders commonly go bad. Try that after you check for loose wiring. I tried to solve a Yanmar over temp alarm for a month. Had no actual gauge. turns out nothing was wrong but the sensor.