Heat Exchange Anode

[piebuss 0]

Hi fellas

 

I went to replace the anode on my heat exchange on the weekend and it was in pretty good nic. After about 9 months I would expect it to be nearly gone, but it was mostly intact, with only a little bit of corrosion.

 

I've been thinking about it a lot now, and now I've convinced myself that the anode is sitting in a bit of an air pocket. It's at the forward end of the heat exchange, which is on a bit of a tilt (less than 10 degrees, but more than 5), and when I pulled it out I'm pretty sure (but my memory's sketchy on this point) that it was dry. Definitely no water came out the hole, but that could have been due to it sucking air in while the water drained out the exhaust elbow.

 

So, I was hoping there was someone with some experience with these things on here. I'm thinking it may need two things done;

 

1. The raw water exits the aft end of the exchange into the exhaust. Once it's in the exhaust piping, it would be free to drain out, so thinking some form of S bend in the exit pipe is necessary. Am I right to think this just needs to dip below water level, then up to the elbow to stop the water draining out?

 

2. The heat exchange is about 1m long (it's a beast). Any air will naturally head to the top (forward) end, so am considering removing the aft cap and having this modified to take an extra anode. Anybody see a problem with this? Would it need to be build up to receive a new threaded hole?

 

It's a Lee's Ford 120hp. No, I have not installed an inboard on the Piedy, it's on an old Kauri chugga.

 

Woody

[BNG 44]

All the Lees Fords have the inclined top heat exchanger, should be an anode at each end as well. That air pocket isn't an issue as its a pretty open system and it flushes any air out real quick rather than air locking up.. You probably have anode (x2) in your transmission heat exchanger if it has one fitted. And don't forget the refridge one if it has mechanical refridge fitted.

 

The secret to making those engines last is warming them up slowly as the water distribution when the thermostat is closed is pretty poor along the block with the front getting hot first and the rear still cold. That causes all sorts of expansion problems and can cause things like split wet exhaust manifolds which split in the middle as one end expands and the other doesnt. So warm it up progressively, I never open her up prior to North head after exiting Westhaven as it hasnt reached operating temp until about then...so around 15 to 20 minutes or until I see around 70 deg c on the temp gauge.

 

Changing the injector pump oil every 50 hours is recommended as it gets thinned out over time and displaced by diesel that slowly leaks under pressure around the seal. Not to mention preventing wear it also reduces smoking when starting from cold.

[wheels 543]

Don't go putting in S bends or anything like that. Leave it as it is designed to work.

[piebuss 0]

Thanks mate.

 

Yes, there's one on the transmission heat exchange, which is working overtime.

There's only one on the engine/coolant heat exchange, which is the one that's got me worried. If that anode is not under water it won't be working correctly right? Therefore while the boat is sitting idle, only the transmission heat exchange is working??? 

 

Re the S bend, that's just my musings regarding the above (i.e. if the fact the anode is not in water is a problem, how do I rectify that). If I'm wrong about the anode needing to be wet, and it will work perfectly fine after the raw water drains away, then the S bend question goes away. But if the anode is meant to be wet by design, then surely this design feature is more important than the design of the raw water hose after it exits the heat exchange???

 

Appreciate the help guys.

 

Woody 

[Island Time 1,235]

An anode MUST be immersed to function.

[wheels 543]

But does the heat exchanger not drain when not in use? The Anode must be in water to work as IT said. But that will be when the engine is running and the water flowing through it. When you switch off, usually the water drains out. Thus no water, no need of Anode to be immersed. If water is in the exchanger all the time, then yes, you will need the anode to be submersed.

[BNG 44]

Presumably your heat exchanger and exhaust manifold below are above water line so when its not running it will naturally (mostly) drain out of the exchanger and manifold which is a good thing and the anode isnt in action as there is minimal if any water left after a cool-down period so less corrosion issues for the components...

 

I wouldn't worry about the few minutes per year its at idle other than wear on the impeller by not chucking enough water through at low revs. Get an aqualarm or similar if its not fitted, then at least you know you have some water going through the raw (seawater) pump although I switch mine off for docking when I'm hovering around idle.