High H2O Temp alarm on with a cold engine

[Chris777]

I need some help, Inboard Volvo-Penta MD 22 diesel, with a M2 transmission. The High water temperature alarm, light and alarm comes on when I start the engine, it stops at around 1500 rpm. I have replaced the impeller even thou the old one was flawless. I am at a loss as to why the alarm for high water temp comes on with a cold motor. Someone suggested the heat exchanger core was plugged. But the alarm is for high temp not low pressure. Anybody have a good guess as to what the problem is?

Thanks

Chris

PS: The marina shop while doing some maintenance did have the engine panel off.... could it be that a wire came off and it got connected back in the wrong place? If so what is setting off the alarm?

[bletso]

Are your high temp and Low oil pressure in parallel? If so it sounds like an oil pressure problem, especially describing an RPM correlation.

[Chris777]

Well maybe. The oil pressure sending unit was replaced about 1 month ago. It had a 3 terminal end but the new one only had 2 and the mechanic stated it was a new model with only 2 terminals. I will check with Volvo, but I do think you are on to something. Thanks.

[Chris777]

Actually the oil pressure sending unit was replaced due to a pin hole in a cooling hose had sprayed water on it and corroded one terminal, thereby setting off the oil pressure alarm, the gauge still showed 60 psi. This was also confirmed by an independant machanical oil pressure gauge. And the oil pressure is still 60 psi..... yes, I think this is where the "gremlin" lies.... we will see on Monday.

[YPSILANTI]

I experienced the exact same problem last week on my Vetus gennie. It was a faulty sensor. Apparently its very common for the sensors to malfunction.

[Symphony]

let us know what the problem was when you solve it, Chris

[Xthewater]

LOP and HWT wires could've been swapped as well.

[Chris777]

As soon as its fixed I will report back.

[Chris777]

We are down to replace the oil pressure sensor..... very problematic. The sensor has 3 terminals and they are marked, G, WK and M. None of these markings is referenced in any manuals. I have the shop manual, wiring manual, so next "fix" is to go down to the local VP service place here in Sarasota and ask how they would wire it in. The sensor is a VP part 860011, if anybody has any ideas.

[Chris777]

No help with the oil pressure sensor, however, I know believe there is an issue with one of the 2 relays. Reason being with the ground connected the remaining 2 wires go to the lights on the start panel. Hot water temp and alarm comes on, if i switch the 2 wires now the low oil pressure and the alarm comes on. Oil pressure is till good...... might just disconnect the idiot lights to see if that helps.