Volvo MD2030 coolant draining

[jmfrazee]

I have a Lagoon 380 with Volvo MD2030 engines. The engine manual that came with the boat says that to drain the coolant you should open the petcock next to the oil filter however there is not a petcock on either engine.

Does anyone know the method to drain these engines in order to change the coolant?

Thanks,

John
Lagoon 380 #199 Alizé

[sailboy21]

Originally Posted by jmfrazee

I have a Lagoon 380 with Volvo MD2030 engines. The engine manual that came with the boat says that to drain the coolant you should open the petcock next to the oil filter however there is not a petcock on either engine.

Does anyone know the method to drain these engines in order to change the coolant?

Thanks,

John
Lagoon 380 #199 Alizé

There is usually a plug on the water pump. You can also just pull off the lowest coolant hose. Make sure the manual you have matches the serial number on the engine. Volvo, like all manufacturers, makes little changes all the time. You can usually find the manual online somewhere. You have to crack something on the top of the head open too, otherwise all the coolant may not drain. Best thing to do so take off the thermostat housing. This allows you to inspect/test/or replace the thermostat too.

[jmfrazee]

Thanks. We tried pulling the lowest hose but that only got us half of the coolant. The manual is one that came with the boat and the engines are original. Lagoon prepared the engine manuals and they lack much in clarity.

John

[firehoser75]

I have one of these engines in my boat. To drain the coolant, take off the cap on the heat exchanger to allow air in, then remove the drain plug located where the manual shows the petcock (next to the oil filter). It is the only plug that has a different shape (I think it is hexagonal - going from memory). I just allowed the fluid to drain into my engine bilge, because on my boat it is fairly deep and separate from the ship's bilge. Then I used a water vac to pick it up.

Good luck with your coolant change ( and flush I hope).

Tom

[jmfrazee]

Tom,

There are two bolt heads next to my filter, a square one and a 6 sided one. Any thoughts on which is the right one. The both are painted over so it looks like neither has ever been loosened.

The previous owner only ran freshwater in the cooling system. That's really living on the edge.

John

[sailboy21]

Only freshwater?? as in no antifreeze? If that is the case it would probably be prudent to take the heat exchanger apart and physically clean it. Regular water will foul/scale the surfaces of anything that gets near the boiling point (around 225 under 5 psi versus 240 or so 50/50). Also would carefully look at all the rubber hose and water pump seals. Fair amount of combustion gas enters the coolant which will deteriorate rubbrer. Get a really aggressive flush and descaler! How many hours on the engine?

[firehoser75]

John,
I think it is the square one. It has been a year since I did the coolant flush, so the exact memory is a little hazy (old timers I guess). I will check when I'm next at the boat. Should be in the next few days as I check it weekly.
I agree with the others about a good flush and maybe even a heat exchanger cleaning (especially if it has been more than one season since the last flush). I suggest putting in a good coolant (Volvo's is good, but can be a bit expensive) at the 50/50 ratio. This stuff isn't just for the winter!

I will get back to you.
Tom

[Idiens]

On my old Volvo MD21A, the square headed ones held anodes, that needed replacing each year and were in the raw water channels. The fresh water was drained through little hexagonal taps, which when broken were often replaced by hexagonal bolts.

[firehoser75]

My internet has been down for a few days.
I went down to my boat and checked the shape of the drain bolt head. it is square, and takes a 20mm socket. The bolt is located just slightly above the top of the oil filter and slightly forward of the filter (assuming the transmission is astern the engine for directional purposes).
I hope this helps with your draining and flushing project.

Good luck,
Tom