Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

[Glastron3.0GLP-C]

My alarm for water temperature, oil pressure and exhaust riser temperature stayed on up to 2000-2500 rpm. Note that it is not loud as when you turn on the ignition, it is just a faint chirping. Oil pressure looks fine on the gauge, temperature also nice on gauge and engine and riser fairly cool to the touch. I disconnected the alarm and run fine for 2 hours.

What do you think is likely the problem? I have a 3.0l GLP-C engine. I have SAE 30 oil per manual and on this last trip at 65 degrees the boat was loaded to capacity with 4 adults and 4 kids. The faint alarm chirping appears also with light load but I believe turns off at lower rpms around 1500.

So, I think the oil pressure switch is defective. Is this an on off switch? Or progressively from normally on becomes off and produces a chirping sound in the transition?

Another posibility is that my oil pressure is low because of the oil viscocity or load.

Sounds like a grounding issue? The grounding should be provided through the water temperature, oil pressure and exhaust riser temperature switches or there is another connection?

On my next outing I plan to disconnect one by one the water temperature, oil pressure and exhaust riser temperature switch to isolate the defective one. What do you think?

 

[Don S]

Re: Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

Disconnect each switch one at a time and see which one stops the sound. Then replace that switch. They are all just on/off switches.

 

[Glastron3.0GLP-C]

Re: Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

I disconnected the oil pressure switch and run the boat for 2 hours without the alarm coming on again so I assume the oil pressure switch is the issue. Now I am looking to buy one and I see the OEM is about $38 including shipping, the aftermarket one here on iboats about $30 and automotive ones around only $8. I guess the automotive one is not ignition proof and it is dangerous to put it on a boat engine compartment where gas fumes might accumulate. Does any one knows if the marine specs apply to oil pressure switches or they are identical parts with a hefty mark up?

 

[TregoMark]

Re: Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

I had a similar problem last year. The alarm would chirp for no appearant reason. Turned out to be a wire from the temp sensor was resting against the engine block and melted exposing wire. That bare wire contact caused the chirp. Fixed the wire and no more alarm chirp.
Of course, it could be a number of things, but always check the obvious first before replacing expensive parts.

 

[Glastron3.0GLP-C]

Re: Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

While I was waiting for my oil pressure switch to arrive I disconnected the old one but left the other two switches (water temp and riser temp) connected. The alarm was coming on at full throttle while I was trying to plane for a few seconds. Then at lower rpms was fine again. Then after a few minutes my temperature gauge went down to 0 and after a minute I slowed down to see what was wrong. This time the alarm was not on. The hose that goes from the thermostat housing to the water pump was busted. I turned off the engine. The bilge was full of water so I took the water out and I called towing. The J-hose had a split along the full length of the hose on the inside. So my assumption so far is that the riser temperature switch was telling me correctly (when worked) that the temperature was high as a result of water shortage. Somewhere in the system there is a restriction and the J-hose was blown. So it is possible for the riser temperature to go high that fast in the first few seconds of planning?
When I changed the impeller at the beginning of the season about 8 operating hours ago, I found that the old impeller was missing one blade. I wrongly assumed that it found its way out of the cooling system and now it seems that it is stuck somewhere. I took the hoses of the thermostat housing and I didn't find anything. My plan is to take the thermostat housing off and the riser off. Where should I look for a restriction or the missing blade? What else should I do?

 

[Don S]

Re: Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

Was you showing low temps (100 to 120) before all this happened?

 

[Glastron3.0GLP-C]

Re: Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

No temperature was always around 150. Never overheated but the alarm was coming on every now and then.

 

[Glastron3.0GLP-C]

Re: Faint chirping Alarm on Volvo Penta 3.0l troubleshooting

What do you think I should check next? The hose from the thermostat housing to the engine circulation pump was blown and I suspected a restriction somewhere. I took out the thermostat housing which was clean including even the small bypass hole under the allen bolt. I checked the impeller that was changed a month ago and it is like new. I backflashed the raw water hose to the power steering cooler and to the water intake at the drive. I flashed the hose from the impeller to the thermostat housing. I took out the hose from the manifold inlet and flushed it with water while opening the drain. I put a water hose on the thermostat housing mounting hole and run it with water coming off the drain and the circulation pump. No sand or anything but clean water came out from the manifold and the engine block drain. Finally i took the riser off and I didn't see anything blocking the restrictor hole or any rust at the manifold or the riser. They look fine to me but see the photos and let me know what do you think?