Draining a yanmar 3GM30F fresh watersystem

[noss41]

I need to drain and refill the freshwater system on my Yanmar 3GM 30F. The hand book that came with the engine says that it should be done every year but fails to explain where and how to go about draining. I have been able to drain some out from the filler cap but no where near the 2plus litres that it contains. Is there a specific drain plug that can be accessed? If not what do I do?

 

[eddie2000]

There are two drain holes, one on each side of the block. They are opened by plastic bolts. One is (from the front of the engine) behind the oil filter and the other is near the dip stick (this one has a plastic drain pipe as well). Between them, they completely empty the block of fresh water. The one on the right is often blocked by sediment. There is also a tap (with a drain tube) near the back of the heat exchanger for emptying the exchanger.

The other problem with draining is if you have a calorifier for hot water. What I do is remove the two pipes going to the tank and block them with corks while I flush the engine. I have flushed out the calorifier but hardly any sediment gets there and it's a pig refilling it.
After flushing, refil the whole system with anti corrosion/anti-frost solution. It will take about 5 litres undiluted (or whatever the instructions for it say).

Hope this helps. Eddie

 

[noss41]

Thanks Eddie

1.Do I have to open the drain holes on both sides of the engine?

2.Is there a trick in opening these plastic bolts without the fear/danger of breaking them?

3.Is there a means of directing the outflow into a container from the draine behind the oil filter?

Thanks

 

[eddie2000]

Thanks Eddie

1.Do I have to open the drain holes on both sides of the engine?

2.Is there a trick in opening these plastic bolts without the fear/danger of breaking them?

3.Is there a means of directing the outflow into a container from the draine behind the oil filter?

1. Yes.

2. Just do it carefully. If you have to, use a pair of pliers. You can get replacements from a Yanmar agent. The trick is not to do them up unnecessarily tight. But look later to check they are not weeping.

3. Not easy for the RHS one. I just let them drain into the engine pan which doesn't drain into the bilge but your arrangement may not be like this.

If the RHS one is blocked, just poke the end of a hanger wire in to unblock it.

Eddie

 

[vyv_cox]

It's best to open all drains to get the block empty. A quicker and possibly easier method is simply to disconnect the lowest hose from the block and let it all run out. Avoids operating the plastic valves, although as has been said they should be opened periodically to keep them clear of sludge. It is possible to put a length of plastic tubing on the valves to direct the flow into a container. On my boat it's easier to let all the coolant run into the bilge and pump it out from there using one of those cheap plastic siphon pumps that I keep for the purpose.