Trying to solve one mystery.

Help me solve the mystery. My Island Gypsy equipped with twin SP225's. After spending last two years on the dry being painted she is ready for a splash. Last weekend I went to marina to start the engines and test all systems before going on the water. My port side engine started with no problem at all, all fluids at normal levels. No the case with the STB engine. When I open coolant cap I found dry completely empty coolant system, checked oil level - everything normal. No signs of leaking coolant in to the bulge, no sign of coolant in oil. I add coolant and start the engine. It starts without any hiccups and ran like a champion. My question is where is coolant could possibly go? If it is not in oil and not inside the bulge. 5 gallons of bright green liquid went where? One thing I have not check is the hot water tank which connects to this engine. Any idea?

Hot water tank is a good place to start. Any steam out the exhaust when its running? Heat exchanger pressure tested? If it was full two years ago and not checked until you ran it, you could have done something and forgot that caused it to drain over that amount of time.

Antifreeze will evaporate over time. But my guess is that it went out the back of your boat during the last season you ran it. Look at your heat exchanger.

pete

Redhook98 said:

Hot water tank is a good place to start. Any steam out the exhaust when its running? Heat exchanger pressure tested? If it was full two years ago and not checked until you ran it, you could have done something and forgot that caused it to drain over that amount of time.

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No smoke, nothing unusual at least. This weekend I will test heat exchanger with my new Stant cooling system pressure tester. All I diid to the engines is general maintenance, like change oil and filters, changed primary Racor's and secondary fuel filters, winterized and that is it. As far as coolant it was there, as far as I remember, well at least 99% sure. The engines was not running from that point. Mystery.

Pete Meisinger said:

Antifreeze will evaporate over time. But my guess is that it went out the back of your boat during the last season you ran it. Look at your heat exchanger.

pete

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It did on one and not on the other? As far as heat exchanger, it is possible, but when the boat was winterized on dry back in September of 2018, the coolant was there. I am 99% sure.

Water heater and engine heat exchanger are prime possible culprits. Drain the water heater and see if you see green on the water side. Since you have since run the engine, water has probably flushed out any coolant that might have gone in muffler through engine HX. Might look behind boat under tailpipe to see if any green is visible on the ground. Or if your muffler has a drain, open it up and see if any green there.

Do a pressure test. Open up any drain (or take hose(s) or zinc plugs off engine HX) and leave it under pressure while looking for green drips from there. 5gal in two years could be a very small leak so give it a few days under pressure.

Also keep a close eye on oil color on dipstick and look in oil fill hole for any signs of moisture.

How to test heat exchanger? Any step by step procedures? How coolant plumbed inside the hot water heater tank? Does it go inside or around fresh water tank? I was driving back home thinking and like i mentioned above I did not test hot water heater tank. Heat exchanger is a high possibility, but not if the engine not running. Am I correct? Are any coloring dye that i can add to a water while testing?

Ski in NC said:

Water heater and engine heat exchanger are prime possible culprits. Drain the water heater and see if you see green on the water side. Since you have since run the engine, water has probably flushed out any coolant that might have gone in muffler through engine HX. Might look behind boat under tailpipe to see if any green is visible on the ground. Or if your muffler has a drain, open it up and see if any green there.

Do a pressure test. Open up any drain (or take hose(s) or zinc plugs off engine HX) and leave it under pressure while looking for green drips from there. 5gal in two years could be a very small leak so give it a few days under pressure.

Also keep a close eye on oil color on dipstick and look in oil fill hole for any signs of moisture.

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I did try to smell the tail pipe and gravel on the ground for any sign of coolant going out that way, but nothing there, at least nothing obvious. I did not find any indication of oil volume increased or oil discoloration. Even after running engine for 5 + min. I check oil level and color, all remains normal.

Don’t forget to check the keel I just drained mine The previous owners removed old bilge pumps from my boat and didn’t fill screw holes and water was going into keel I epoxied holes with two layers of cloth on top.

Busterbrown said:

Don’t forget to check the keel I just drained mine The previous owners removed old bilge pumps from my boat and didn’t fill screw holes and water was going into keel I epoxied holes with two layers of cloth on top.

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What should I look for and how did you drain keel?

My Grand Banks has a hard plastic tube that goes to the bottom of keel I used a wet dry vacuum attached to tube and removed water I would think your keel is similar to a GB but hopefully someone else can chime in.

What was the status of coolant in your coolant recovery bottle?

rgano said:

What was the status of coolant in your coolant recovery bottle?

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All dry, on this engine. On the other side it has maybe a quart, probably less.

Vadim said:

I did try to smell the tail pipe and gravel on the ground for any sign of coolant going out that way, but nothing there, at least nothing obvious. I did not find any indication of oil volume increased or oil discoloration. Even after running engine for 5 + min. I check oil level and color, all remains normal.

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I wish you took some picture of this... Can imagine the guys around watching you smelling tail pipe and gravels, I am sure they were wondering if you were sane lol Just kidding

L

Vadim said:

All dry, on this engine. On the other side it has maybe a quart, probably less.

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So that means the engine was low (empty?) of coolant when last shut down, AND that there was enough vacuum developed as it cooled to suck the bottle dry. I once found a drip of coolant on the bottom of the engine's flywheel pulley. I followed the trail upward to find coolant had been steaming out of the worn circulating pump bearing while the engine was operating; thus it would not puddle up i the drip pan. Like others, I would suggest checking the heat exchanger and water heater first, but don't ignore other contributing candidates like this one. Also look for a cracked exhaust manifold and/or elbow.

Thank you all very much.

Vadim said:

Thank you all very much.

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We are all glad to help. Now you have to remember to come back to this thread and fill us in on the outcome.

This is a good mystery! Good luck

rgano said:

We are all glad to help. Now you have to remember to come back to this thread and fill us in on the outcome.

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I will.

Remember boat engine circulating water with antifreeze is a poison and most boat hot water units have only single wall piping .

That green stuff can kill you!

The off grid folks water heating units can be had with double wall tubing.

Mystery solved. As I was expecting disappearance of coolant has something to to with hot water system.. Well it was slow leak forum old partially damaged Bose right at engine coolant supply to hot water tank system outlet. Damaged part was cut, refitted and secured. Result, pressure was normal, those dry. No loss of coolant after running engine for 30 min. That was easy and not expensive at all Thank God.! Thank you all for helping me solve this mystery.

Vadim said:

Mystery solved. As I was expecting disappearance of coolant has something to to with hot water system.. Well it was slow leak forum old partially damaged Bose right at engine coolant supply to hot water tank system outlet. Damaged part was cut, refitted and secured. Result, pressure was normal, those dry. No loss of coolant after running engine for 30 min. That was easy and not expensive at all Thank God.! Thank you all for helping me solve this mystery.

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One question, how do you know that it came from that hose? Any leak you found? Did you find the missing coolant? Just wondering.

L

Lou_tribal said:

One question, how do you know that it came from that hose? Any leak you found? Did you find the missing coolant? Just wondering.

L

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When I preasurized the system with 7 psi I start looking around hot water heater and all connection hoses. And I touched that one hose which was soaked wet slow leak. That was the only one spot i found. And that was it.