Hot Water Heat Exchanger Coolant Change

[KZW]

I'm possibly a bit slow here. I have a C-310 with M-25 XPB with a hot water heater. The hot water tank is in the rear compartment just forward of the rudder post. The water is heated by running engine coolant through a heat exchanger in the hot water tank.

Question: When changing the coolant, how does one drain the coolant from this heat exchanger and associate hoses.

The picture shows the coolant hoses running to the hot water heat exchanger from the pump on the front of the engine.

 

[Stu Jackson]

Coupla ways:

Drain at the lowest point you can get to, and ignore what's left in the hoses to the heater.

Drain, refill with distilled water, run engine, drain again, refill with antifreeze (using distilled water, of course).

Your boat, your choice.

 

[KZW]

Stu,

Good to hear from you. The lowest point is an issue. The hot water tank fittings are almost impossible to access. The only thing I can figure is to remove the hoses from the pump and lower them into a shallow pan placed on the deck next to the engine. Even at that, I'm not sure the coolant will drain.

it was my fondest hope a 310 owner with this set up can tell me how he does it (hopefully and easy way)

 

[Stu Jackson]

Our engines are almost identical.

Here's how I do it:

How to Burp Your Engine (Reply #6) http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

That side view of your engine doesn't show the front, I'm not that familiar with it.

 

[KZW]

Front of Engine. You can see a hose going from the pump that runs from the heat exchanger and another that works back to the coolant tank. I'm not even sure in which direction the coolant flows.

 

[woodster]

take a dinghy air pump and hook one hose to it and put the other in a 5 gal bucket and pump away

 

[KZW]

Woodster,

Thanks. I figured I was going to be forced into that, but was in hope of an easier way. The hoses are not inclined to come off the fittings. I need to cut way several of the wire ties to try and get a purchase on them to twist while applying heat?

Now all I need is a dinghy!!!!! (I have a pump that fits in my drill. I just need to get matching barbs and connectors.)

 

[woodster]

any kind of low pressure air supply will do ...high pressure works but you stand a good chance of blowing something up ....i like the dinghy pump because it will move a lot of air at low pressure...you could use one of those cans of air like they blow off computer keyboards with a little tape and the spray tube that comes with it ...i think they are called dust it or some thing like that

 

[KZW]

any kind of low pressure air supply will do ...high pressure works but you stand a good chance of blowing something up ....i like the dinghy pump because it will move a lot of air at low pressure

Thanks very much. I had not considered that.

So, does the flow go through the pump, into the hose, through the heat exchanger and back to the manifold, or the other way around?

 

[Stu Jackson]

Woodster,

The hoses are not inclined to come off the fittings. I need to cut way several of the wire ties to try and get a purchase on them to twist while applying heat?

When you put them back on use some Lanocote. Mine always come off easily.

Sorry to hear you can't find any easier way. Good luck.

Idea?: you could wait til spring and find a dockmate with a dinghy.

 

[woodster]

Idea?: you could wait til spring and find a dockmate with a dinghy.

Stu its already summer down there

 

[Stu Jackson]

Front of Engine. You can see a hose going from the pump that runs from the heat exchanger and another that works back to the coolant tank. I'm not even sure in which direction the coolant flows.

Top of the belt to the left of the alternator is the coolant pump. There's the gray hose underneath, just like in my picture, a tad different, but can you get to it?

Doesn't matter which direction the coolant flows, you don't run the engine to drain it. Just have to take the pressure cap off the manifold.

 

[KZW]

When you put them back on use some Lanocote. Mine always come off easily.

Sorry to hear you can't find any easier way. Good luck.

Idea?: you could wait til spring and find a dockmate with a dinghy.

Lanocote is a great idea, thanks. Regarding spring: In the Florida panhandle today it was 76 degrees, the bay temperature is 70 degrees. The flowers and trees are blooming. Spring is here!!! I wash and wax the boat next week. Fluid exchange follows.

 

[Stu Jackson]

Stu its already summer down there

Aha! FL. I heard it got down to 40F but that was last month!

 

[KZW]

It was a cold winter for us. It dropped below freezing at least four times. We had freezing rain for about 30 seconds one day. Traffic came to a standstill. I personally saw four, maybe five ice crystals. I almost bought a parka. The temperature in the bay dropped to 49! I had to put a heater in the boat!!!!!!

 

[JK_Boston_Catalina310]

I can give more details in the AM from a computer if you need it. The coolant pump is on the to starboard side of the motor. The Sherwood pump on the lower port side of the engine is the raw water pump that pumps sea water into the heat exchanger.

On the lower port side of the engine is a block drain for draining antifreeze.

In the back at the water heater there should be a plastic T with thumb screw bleeder valve.

To drain the system I disconnected the T at the water heater and drained both sides into a bucket. Then I drained the heat exchanger by removing the hose to the water heater. Then I drained the block with the block drain. I then used a shop vac to remove as much as I could from the rest of the system.

I then replaced all my hoses and the thermostat. But l were original and 11 years old at the time. I also disassembled the T from the back, cleaned and put back together with new pipe dope. Don't use too much. I also removed my heat exchanger, cleaned, pressure tested and repaint it. Reassembled the whole system.

I then Flushed the system by removing one of the hoses from the coolant pump that goes to the water heater. I connect a drill pump to the hose and pump DI water through until the effluent water was clear. (I connected clear tubing to the other coolant pump to direct the effluent into a bucket and on the pickup side of the drill pump). I then reversed the connection and did the same thing pumping into the coolant pump with the effluent coming from the hose. I then pumped properly diluted coolant through the system with the drill pump. When proper color coolant was coming out, I reconnected all the hoses and then topped off and bleed the coolant following what Stu had in his link.

Hope this is clear enough. Let me know if you have any questions.

Good luck and fair winds,

Jesse

 

[KZW]

I will give it a shot next week when I'm off from work. Spring cleaning. Diving on the hull to remove the winter slime now that the water is warm enough, changing all the fluids, waxing the hull, etc. Waxing is harder in that that boat is in the water