MD2030-D Coolant leak

[Mark L]

Hi, looking for advice on an issue that I've been having with a (new to me) MD2030-D, the first volvo penta engine that I have owned.

First time on the new boat, taking her on leg 1 of the trip from the south coast up to Scotland. Initially no issues whatsoever with the engine, including about 7 hours under engine when the wind dropped off on Sunday night. However, 4 or 5 hours later when I started the engine to come into the marina, the high temperature alarm went off. On later inspection, I noticed that the coolant was low. Topping the coolant up solved the temperature issue, but the coolant continued to drop substantially when the engine was running. I would estimate a loss of around a litre per hour, but no visible coolant under the engine or in the calorifier compartment. No evidence of water in the engine oil, and the engine continued to run fine if topped up. Coolant does not drop when engine is off.

Possibly related: I initially thought that the raw water flow was low and the exhaust sounded a little dry. I pumped some air down the inlet pipe and it felt like there may have been a slight blockage before I could hear bubbles coming through. May have been my imagination though, and this made no difference to the coolant leak. Impeller and strainer are both fine.

Reading a bit online about the cooling system on these engines, my first thought is that it could be the rubber end caps that seal the inlet, and separate the FW and SW sides of the system, but I thought I would see if any other Volvo Penta owners had experienced similar or had any other suggestions on what might be causing this.

Thanks!

 

[VicS]

Hi, looking for advice on an issue that I've been having with a (new to me) MD2030-D, the first volvo penta engine that I have owned.

>

Reading a bit online about the cooling system on these engines, my first thought is that it could be the rubber end caps that seal the inlet, and separate the FW and SW sides of the system, but I thought I would see if any other Volvo Penta owners had experienced similar or had any other suggestions on what might be causing this.

Thanks!

Very probable.
At working temperature the coolant pressure is higher than the seawater pressure so coolant can be lost to the seawater if the smaller clips are not tight or the caps not fitted correctly.

When the engine is cold there is potential for seawater to find its way, by the same route, into the coolant. If this proves to be the cause of the coolant loss it may be contaminated with seawater therefore change the coolant at the earliest opportunity.

 

[tillergirl]

I had a 2030B with Tiller Girl for over 20 years. Occasionally I would lose coolant via the pressure cap (with the 2030B there wasn't a bottle). Always it was partial blockage at the inlet. The suck of the raw water pump was surprising powerful that the pump continued to provide some water. On a cold day, some steam in the exhaust was a clue as the temp was rising. Also I heard a different in tone in the exhaust caused by the reduction of water flow. Only once did a jelly fish completely block the inlet (it was a big one!). The rubber ends and 'O' ring could be the cause but I would see if everything is back to normal first and if it is fine, I would suspect a temporary blockage.

 

[Mark L]

The rubber ends and 'O' ring could be the cause but I would see if everything is back to normal first and if it is fine, I would suspect a temporary blockage.

Thanks both. Just to be clear, if there was a blockage (and I'm not 100% sure that there was), it is certainly clear now with lots of water running through the exhaust. There is, however, still a fairly substantial loss of coolant....

 

[Ammonite]

Worth checking the water injection point on the exhaust elbow. If you have a cast iron elbow the injection point is prone to rusting and the restricted flow / back pressure forces coolant / sea water past the rubber end caps...leading to the symptoms described by VicS.