Oil alarm going off

[Murdog]

Had my 1997 3200 SCR delivered last Thursday and was planning on heading out Sunday. After starting up the engines after 3 or 4 minutes the Alarm started to go off. I checked all of the engine/gear lube oil levels and all were fine

Did a re start and same thing happened--shut her down again.

My friend suggested I start one engine at a time to see the culprit--I did so and never heard the alarm again--so off we go.

Went back out yesterday and alarm came back on--did the one start at a time and it only happens on the starboard engine. I also noticed that on Sunday when it ran--without the alarm going off the oil pressure was fine but when the alarm was going off--the oil pressure was low.

Could this be a faulty gauge?
Or a faulty sensor??

Note--At Sea Trial there were no issues with alarms.

Your advice is greatly appreciated!!

[speedysprocket]

If the gage is low and alarm is going off, have to think something is wrong. What does the gage say? How many hours on the engine and what oil was put in them?

[mmwjr]

The alarm uses a oil pressure switch and the gauge an oil pressure sensor so if both are indicating an issue it is probably real. If you increase the rpms when the fault is occurring does the oil pressure increase? The engines oil pump has a built in pressure relief that may be faulty, however to fix the engine needs to come out.

You can install a mechanical gauge to get a third measurement.

Hate to say it but by removing one wire the alarm would not sound so if the sell was that type of person he may have pulled on over on you.

[Murdog]

I just had my sales broker tell me that it could possibly be the oil pressure sending unit/sensor unit.

Does that make sense?

To answer the other questions that have been asked I have not been out to the boat again since last night

[mmwjr]

Originally Posted by Murdog

I just had my sales broker tell me that it could possibly be the oil pressure sending unit/sensor unit.

Does that make sense?

To answer the other questions that have been asked I have not been out to the boat again since last night

As I stated the alarm sensor is a switch and the helm gauge has a separate sensor. if both are indicating a problem it is probably real. I guess both could be bad but that would be rare and for both to fault at the same time even more rare.

[mmwjr]

When you were out last and it was fine what rpm range were you at verses when it was bad?

[donald]

What are you calling low oil pressure???
Did it drop to 0?
A cold engine will have a higher oil pressure than a warm one!!
What engine, drive do you have?
Would help to know so we can help you better!
Don

[Murdog]

Sorry it took so long to respond--I have been to the marina 3 times since my alarm went off and all 3 times I have started tebost and no alarm goes off and Oil pressure and temp are good.

What do you guys make of that??

5.7 Mercruisers

Thanks

[Murdog]

Sorry it took so long to respond--I have been to the marina 3 times since my alarm went off and all 3 times I have started the boat and no alarm goes off and Oil pressure and temp are good.

What do you guys make of that??

5.7 Mercruisers

Thanks

[mmwjr]

Did you just start it in the slip or take it for a ride? Did you let the engine get to normal operating temp, fully warmed up?

[Murdog]

Just in the slip the last 3 times. Weather wasn't good to go out.

[mmwjr]

You'll need to test it at sea fully warmed before anything can be concluded. I suspect it will still alarm and the gauge will read low. What pressure is the gauge showing with the alarm sounding?

[Murdog]

It has been a week since it went off--but I believe it was at 40.

[donald]

If the oil presssure was at 40 psi I would ck the three switches that control the warning alarm! Oil Pressure N-C switch near oil filter ( not the one for the guage), Water Temp on T Stat housing gain not the one for the guage, and the out drive lube bottle!
Those are the only ones that would set off an alarm!
Good luck!
Don

[mmwjr]

Originally Posted by donald

If the oil presssure was at 40 psi I would ck the three switches that control the warning alarm! Oil Pressure N-C switch near oil filter ( not the one for the guage), Water Temp on T Stat housing gain not the one for the guage, and the out drive lube bottle!
Those are the only ones that would set off an alarm!
Good luck!
Don

Don is correct; 40 psi is not low therefore you need to isolate which of the three sensors is setting off the alarm. Try disconnecting them one at a time until it stops alarming and you found the issue. The lube bottle is know for getting stuck but the oil pressure one is also know to go bad.

[speedysprocket]

Getting the oil up to temp where it will thin out and drop pressure some also takes 2-3 times longer than just getting water temp up to normal. That could be 20-30 minutes just idling in the slip.