Dumping Antifreeze

[DougSea]

Hi Rob,

How long can the engine idle without heating up? Also, how long should I let the fresh water circulate before dumping it?

I would just watch your temp gauge. Idling diesels take a long time to heat up, there's so much mass to them.

I would also leave the water heater lines connected and make sure the valves (if you have them, and you probably do) are open. You want to change ALL of the antifreeze in your system. BTW - if your water heater is full of fresh water it also acts as a heat exchanger and will further delay engine heating as the water in it warms up.

As for how long to leave it in, I would give it a SWAG at 20-30 minutes.

(Scientific Wild Azz Guess)

[RobS]

Disconnect and drain the water heater hoses. The hoses and coil in the water heater hold quite a bit of coolant. You can also run a fresh water hose through them to completely clear them out and the coil too. Then reconnect the hoses and fill the engine with distilled water. I'd say only a few minutes of idling and you're good to drain the water and fill with 50/50. Overheating will not be a concern.

[rcornejo]

Hi Rob and Doug,

Great advice. I will do all of what you suggested this coming Saturday. The boat is actually about 150 miles from where I live.

I will post my results and let you know how it turns out.

[mike66]

One other consideration. If you've flushed with water (preferably distilled) there is going to be leftover fresh water in the block and hoses. The best way to add the new is to find out the capacity of the system and add half that amount of straight coolant. Then top off with distilled water. That will ensure a 50/50 mix or close to it.

[rcornejo]

Hi Mike,

Thanks. I will do that.

[rcornejo]

Antifreeze came out and new stuff went in. I took everyone's advice and the project came out great. I ran the boat for about two hours and it never went over 150 degrees. I am assuming that's good. If it's not, let me know before I head offshore in two weeks!

[RobS]

Glad it went well. 150 under load actually seems kinda cool. What did she run at before the recent overhaul?

[rcornejo]

Hi Rob,

Yes, it ran well. However, we did not overhaul it. We simply made a lot of repairs to it. I hope it holds up so that I don't have to get it replaced. Time will tell.

[DougSea]

I think Rob's referring to all of the efforts to clean up the cooling system. 150 does sound a bit on the cool side, and like Rob I'm wondering what sort of temps you were observing in the past (prior to flushing). The engines in Sonny IV run bang on 185 and I recall the "Beast" in Sonny III running in that same range.

[rcornejo]

Hi Doug,

Previously, it ran about 150 -155. I am not sure if that was good or not but that's what it was at most of the time.

[Serenity]

I have been following this thread and I was thinking that wouldn't the temp of the bay, ocean, lake stream, red sea or whatever body of water you boat in, have a bearing on the fresh water side temperature of the engine. On another note, is there a difference between distilled water and water that comes from a de-humidifier? They both would have no impurituies.

[DougSea]

I have been following this thread and I was thinking that wouldn't the temp of the bay, ocean, lake stream, red sea or whatever body of water you boat in, have a bearing on the fresh water side temperature of the engine.

Just like a car should run at a constant temperature, regardless of the outside temps, so should a marine engine running in whatever water temperatures it finds itself. There is a thermostat that adjusts how much of the freshwater (sealed) side goes through the heat exchanger (radiator in a car) and therefore the temp of the engine.

On another note, is there a difference between distilled water and water that comes from a de-humidifier? They both would have no impurituies.

Dehumidifier water is, for practical purposes, distilled water. Just make sure the collection container and coils are clear of "stuff". My mother used to use dehumidifier water in her iron to avoid scale build up and such.

[Serenity]

Back in the day I had a 28 Luhrs with a 165 Perkins diesel. (The original owner was ahead of his time in ordering the boat with a diesel). I always ran about 165 all day. One year Peconic Bay was extremely warm, over 75 degrees and I was hitting 175 plus on the thermostat. As soon as I went thru Shinnecock Locks and through the inlet to the ocean, I went right back down to 165. Maybe it was the algae in the water due to heat trhat was causing blockage for awhile.

[DougSea]

Back in the day I had a 28 Luhrs with a 165 Perkins diesel. (The original owner was ahead of his time in ordering the boat with a diesel). I always ran about 165 all day. One year Peconic Bay was extremely warm, over 75 degrees and I was hitting 175 plus on the thermostat. As soon as I went thru Shinnecock Locks and through the inlet to the ocean, I went right back down to 165. Maybe it was the algae in the water due to heat trhat was causing blockage for awhile.

That would seem to point to an inefficiency in the boat's heat exchanger. If the thermostat is fully open, allowing maximum cooling, and the engine needs to get rid of more heat that the exchanger is capable of then you would see an increase in engine temp. This is why it's important to occasionally clean the raw water side of your cooling system.