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Water temp alarm went off

G

gastite101

Member
It's been a while.

went out and everything ran great. On the way home the water temp hit 240 and the alarm.
ran one engine home.
i know my elbow and risers will need to be replaced.

today I went down and noticed all my antifreeze is gone, I even took the stat housing off and nothing.
i did not notice any white smoke or anything like that.

do I have a manifold that's bad and its leaking out through my exhaust
Could it be my raw water impeller not working and the engine got hot enough it vaporized the antifreeze.

I checked spark plug and they were dry and no moisture. Checked the oil, looks good.

wondering where hell did my antifreeze go.
 
2X on out the exhaust!!!

pressure test your heat exchanger using an auto type radiator tester....once you verify it won't hold pressure, order a new one and start saving your money...the other one won't be too far behind...
 
Im a HVAC commercial mechanic and I work on huge refrigerant compressors but I am a little confused why if I test the heat exchanger and it does not hold pressure replace it and problem solved?
Please, Im Just asking.

My thinking is if it does not hold pressure and is leaking or draining where would it drain too because my boat has no antifreeze in the bilge. If bad heat exchanger would it really go out the exhaust?

makomark

I will do what you request, its simple and I trush this site.
 
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Here's the deal: Your manifolds (and possibly the risers as well) are cooled by anti-freeze. In a RWCooled motor, by contrast, these parts are cooled by the same water that flows through the engine. Now, with a FWCooled motor like yours, a plate is used to block off the last part of the system (the risers, usually) so the system is sealed. IF this plate develops a leak--and they sometimes do over the years--then the coolant goes out the back as raw water would in a RWCooled system.

Jeff
 
I can say that i have seen many more heat exchangers fail than I have block off plates...either way, the pressure tester will show if the integrity of the closed side exists...if it doesn't (highly likely due to the sudden loss of coolant), then you need to find the leak are replace the failed component(s)...

A failed heat exchanger (internal leak) or a leaking block off plate would allow the higher pressure coolant side to escape into the lower pressure raw water side...that water goes out the exhaust...
 
I am renting the tester tomorrow.
question, I have not filled up the heat exchanger yet, should it be full before I test or does it matter.
i would have to fill and run to top off and the engine will be warmed up.

thank you team
 
Spoke to a mechanic today and he said two things, heat exchanger or head gasket. Very rarely does a block off ever go. He was funny because he looks at this site all the time and saw this.
 
Make sure you tell us what you find. It isn't clear to me an engine should overheat because of a coolant leak into the heat exchanger (which filled with raw water) although you will certainly get salt into your coolant and eventually you will have a rather complicated raw water cooled engine. Because while a you will not maintain pressure in the coolant with a leak into the exchanger, as long as both pumps are working it should still circulate and cool. But it had to boil to push a lot of the coolant out. So I like the head gasket theory more (that will definitely cause boiling) although if the engine ran smooth until it overheated that does not work well either. Or was the engine actually strong until the alarm went off? Underway with two engines one might not notice a weak one.

In any case you have a coolant leak, and if it is not into the bilge or the oil it is into the exhaust by some route. Good luck.
 
A little fyi today.

I filled up the Starboard engine with antifreeze.
When I started the Starboard engine before I did below I noticed antifreeze coming out the exhaust for
About a minute then a whitish look for a minute and then clear water.

I ran both engines the same time at the same rpm.
Port- I touched the top part where you poor in your antifreeze and it was hot.
I ran my hand on the bottom were the raw water goes and it was cold at the ends and a little warm in the middle.
Starboard- top was hot like it should be
Bottom was almost as hot has the top. The ends were cold but for about an inch, but that’s where the hoses come in.

After this was done I took the spark plugs out and looked at each one and they were all dry.
I checked the oil and no water or white film anywhere on the stick or on the caps of the Starboard.
 
The less air in the HX, the less pumping with the tester....

As the closed side gets hot, its pressure exceeds the raw side and the coolant is forced out...there may be some residual "backflow" after cooling off but there will never be enough raw water inflow to provide any cooling....too much residual air...
 
God, these heat exchangers are not cheap, I was thinking $400-$500 but the cheapest is $700 and all the way upto $1200. Is there any sites I should look at for getting better pricing? Just asking.
 
You might search the net for an exchanger repair shop. They fix radiators, right? Must be somebody who repairs exchangers as well.

Jeff
 
I think you may find a local rebuilder who may take on the task....I'd be surprised if you found somebody who does it on a blind exchange basis...too much corrosion concerns to bite you without a good inspection on the core...

There are shops that will build you a custom one and it is likely to be cheaper than MSRP as they don't have to incur the cost of "storing it"...

A more risky option is a marine salvage yard...but they know what you've been asked to pay for a new one...
 
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