MD2020 temperature alarm on tick over?

[rickywright78]

Can I resurrect this thread and ask how the OP got on? @shaunksb Did your issue resolve itself or what did you do to fix it?

I have a MD2010 that has started having a coolant alarm issue - but it seems to be random... the alarm beeps, and coolant overheat light comes on, but then it goes off again, and could beep on and off a few seconds at a time for a while - sometimes staying on permanently... but if you rev it up it also stops. I've ran it for 10mins at full revs and no overheat alarm... but definitely alarms on lower revs.

It's pumping raw water well and I've recently cleaned the heat exchanger and checked the exhaust elbow so all is clear and clean there. I've also now drained and refilled the coolant... and bought a lazar temp gun to check the coolant and engine temp - and all is within normal range?

Any thoughts or advice would be much appreciated!

 

[shaunksb]

Can I resurrect this thread and ask how the OP got on? @shaunksb Did your issue resolve itself or what did you do to fix it?

Well I have, I think, but only last week.

My boat has been put back in this week but I asked the on site engineers at SYH French Marine to give it a full service the other week.

What they found was that the entire top half of my heat exchanger was perfectly clear but the bottom half was completely scaled up.

It had been sitting for quite a while before I bought it and I only used it sparingly for a season before laying it up for a refit while I carried on with my other boat.

It seemed to pump through fine but I can only assume on that time on tick over there wasn't enough cold water being flushed through to percolate through to the lower part of the heat exchanger and the top of the engine got disproportionally hot and set off the alarm.

Once the engine was up to it's 1800rpm cruising speed there was enough going through the top to keep the bottom cool too.

I'm going down this weekend so I will try it tied up to the pontoon first.

That's what I think has happened anyway but someone from more of an engineering background might be able to add something?



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