I’m posting with this topic because I’m checking my MD2 engine, and I have some doubts about temperature values. After one hour running, despite of having at temperature gauge 60º C, with a laser thermometer, I verify that the front head I have 70º C and at the back head I check 80-85º C. Have you already check the temperatures of your engine heads temperatures?
I change and fully repaired the water pump and the thermostat.
Good evening Pedro, me have just verified on the documentation workshop of volvo, the thermostat on a MD2B, opens to 60 ° and closes in 74 °. I can send you by e-mail technical doc (in French for this evening) by e-mail if you want.
I did not make grip(taking) of temperature, but if it of big there differences, it can mean a poor circulation of the sea water in the engine block.
I’ve checked the thermostat and its opening, at 72 C. So I order a new one, that I didnt installed yet. The motor has a good debit, the water pump is new (impeller and cam) . The needle of the gauge reaches 70 C in one hour running. What intrigues me is the temperature difference between the heads of 10 C aprox.