Coolant Smoke or more?

[niner_gang]

New to us 2004 Hunter 33, with a Yanmar 3YM30. Very embarrassing, but we left the marina with the raw water seacock closed.
15 min later, the entire cabin was filled with grey smoke. Shut the engine off, aired everything out and had to be towed, since at the time, didn’t know it was closed.
Come back day later, refilled heat exchanger tank and coolant recovery tank, and ran her for 20 min at dock, no issues.
engaged drive and in another 5 min or so, some white/grey smoke wafting up from exchanger. Very small amount, camera couldn’t even capture it, and I had spilled maybe half ounce of coolant during refill

question, is it possible this is the coolant burning off manifold after finally reaching boiling point? Or something larger. Also, any other issues I should now be on look out for after overhearing engine? Audible alarm for temp is not operational, and on list of items to fix. The temp light was on however, but we didn’t notice it until the smoke in engine compartment was fully going.
Appreciate any help

 

[Benny17441]

Change the engine oil: not related to your smoke but heat is the #1 enemy of oil viscosity. Have you inspected the raw water pump impeller? It is very likely that rubber impeller vanes may have broken off when the pump is ran dry even for a few seconds. Broken impeller vanes will lead to further overheating as the pump will loose capacity to move water and the broken pieces of the vanes may clog cooling passages. Give your raw water discharge port a quick glance to see if water is running through the system. Your exhaust port is located below the waterline at the stern of the boat, with the engine running should should be able to see turbulence in the water confirming there is water flow. Unless you had observed it prior to the overheat you may not have a point of comparison to determine if the flow is normal or diminished. A serious overheat could damage an engine but these Yanmar engines are pretty hardy. just start by insuring proper water flow and then take it from there. If the impeller vanes are broken you need to look and account for every little piece as in the future that llittle piece could be the cause of another overheat. Good luck. We have probably all done that but a trick to avoid repeating it is, "whenever you shut the seacock hang the boat keys on the valve lever".

 

[kloudie1]

Another thing to check is the exhaust hose close to the elbow. Without water to cool the exhaust gas, you can melt a hole in the hose or muffler.

 

[Ralph Johnstone]

Firstly, welcome to the site. Count this as the luckiest move you will ever make as you post indicates you are at serious risk of carbon monoxide poisoning.

Adhere to above comments from @kloudie1 and @Benny17441 .

Additionally a few other questions:

1. Where did the smoke in the cabin come from. Sounds like there was or you've now created an exhaust gas leak. Test all exhaust hoses, muffler, and all exhaust gaskets. You now have a loaded gun to your head if that's the case.

2. Where did the coolant go ? It should have gone to the coolant overflow tank. I can't really see it blowing all over the place in an overheat situation.

3. Do not start the engine again until you have a high temp alarm installed. You are running the engine blind.

Hunters are a bugger with the underwater exhaust because you simply cannot tell if cooling water is being expelled to the exhaust. Don't ask me why, but two weeks into owning my brand new 1999 Hunter, I installed a sea water flow alarm and an engine temperature readout gauge.











Have I thoroughly scared you ? ? ? Good, chances are you won't become one of the ever increasing CO poisoning victims which are becoming more and more common every year.

Good luck with this and let us know how it goes.

 

[Ken Cross]

You can install an engine temp gauge. I watch ours regularly (we also have a light and a beeper). When you hear the alarm, it's too late. If you can see that the temp is getting too high, it gives you time to set the hook, or throttle back and return to the dock. You can also estimate the effectiveness of the cooling by disconnecting the hose from the mixing manifold and put your thumb over it while someone starts up for a couple of seconds. This doesn't tell you about the exhaust system, however.

When we bought our present boat, we had all kinds of cooling issues. We had a temp gauge stuck at 160, a bad raw water impeller, a piece of hose with an internal restriction, a partially clogged heat exchanger, a plugged up mixing elbow, and a leaking engine recirculating pump. I kept thinking I solved it until I saw the next problem. Sometimes it took a few miles to identify the next item. I don't think the folks we bought it from had ever started it up. (they only owned it a year and lived aboard). When we did sea trials we didn't run the engine long enough (temp said 160). I was concentrating on what the sails looked like.

Ken

 

[capta]

To answer your question directly, no, the coolant should not be making steam or smoke in the engine room, if it is on the engine. A normal diesel runs at 160 to 180 f, which is not hot enough to boil water.
As above, check your water system intake to exhaust plus all the hoses after the riser, and if all seems good, then you must consider more serious problems, such as a warped head or blown head gasket, both of which will cause smoke in the engine room.
Call a mechanic if you don't know how to do a compression test. That will tell you a lot if you've found no reason for smoke in the engine compartment.
Good luck.

 

[JoeWhite]

Eventhoug I store and wrap the ignition key around the raw water intake, I managed to not open the valve for a second time. Fortunately I noticed the unusual 180 F temp and I quickly opened the valve. My solution was to install a magnetic switch on the valve handle so that when the handle was in the closed position and I turn the key to the ignition position I would see a dedicated bright LED at the console blinking and sounding a loud buzzer.
This alarm sounds even before I start the engine. Since then it has happened only once that I forgot to open the valve. I test it periodically to make sure it works.
PM me if you like to see images of the setup.
Haro.

 

[Scott T-Bird]

Whenever you start up and run your engine, you should always be very vigilant about the exhaust. If your exhaust is below the waterline, that makes it harder, but you should still learn to recognize the signals. What looks like steam at the exhaust and a 'hollow' engine noise are usually the first indicators that something is wrong, if you can't actually see the exhaust stream (underwater).

It is actually not uncommon at all to have a raw water flow restriction. It happens all the time, for a variety of reasons. Usually, it happens when seaweed or grass clogs the intake. I've often started up without opening the seacock (and I will testify that it takes more than a few seconds to destroy the impeller - a few minutes may be a different story). Last summer, I ran the boat for a few minutes when we were about 12 miles offshore when I found the exhaust steaming just as I was turning the engine off. It turns out, the water pump belt had failed, even though it was functioning when we left the dock.

When you experience the signs and sounds, you learn what to notice almost instinctively. In my last case, I could hear the hollow sound and was slowing down already, before noticing steam around the exhaust, even though the exhaust is underwater when we are underway.

Your impeller surely needs to be replaced. When you inspect it, it may look completely normal. But it is already damaged. I've changed at least a dozen impellers for failure over the past 17 years and not a single one looked any different than a brand new impeller. In fact, despite several instances of raw water flow restriction, I have yet to discover an impeller that lost a vane or even any particle of a vane.

However, I've never experienced smoke inside the cabin as a result of this problem, so you may really have cooked your impeller, and it may be a significant project to recover all the particles. But one thing is for certain, you have to replace your impeller whether it looks ok or not. While you have the water pump apart, make sure there is no restriction and you have water flow to the pump.

I'm guessing that if your exhaust is below the waterline even at rest, it will be difficult to recognize if the turbulence beneath the water is a combination of water and gas, or just gas. The sound of exhaust is usually the clue that I most carefully observe. In my case, when I'm sitting at the dock, I can see and hear the water spitting out above the water surface, but as soon as I am underway, I can't really see it as the boat squats just enough to submerge the exhaust. That is when the sound is most critical to me.

 

[Calif. Ted]

Change raw water pump impellor it's probably toast, I've seen them go in minutes when run dry. In fact I've seen vanes break off for no discernable reason.

 

[Ralph Johnstone]

then you must consider more serious problems, such as a warped head or blown head gasket, both of which will cause smoke in the engine room.

Blown head gasket is a very likely but just too painful to think about !

 

[Scott T-Bird]

I'll just add, I have turned over my engine without the seacock opened far more times than I can count. I don't find it to be anything to be particularly concerned about if I catch it real quick. Every single time I start the engine, my very first concern is whether or not the exhaust is spitting water or not and that takes not more than 5 seconds before I shut down based on the realization when I haven't opened the seacock. If you don't know whether or not the exhaust is spitting water almost immediately upon starting, your mind is being neglectful in my opinion. It's the very first thing that you have to confirm.

The last time I started the engine with the seacock closed was right after I changed the impeller. I was so frustrated that the exhaust wasn't spitting water that I didn't realize right away that I had closed the seacock to change the impeller!

 

[Tally Ho]

I'll just add, I have turned over my engine without the seacock opened far more times than I can count. I don't find it to be anything to be particularly concerned about if I catch it real quick. Every single time I start the engine, my very first concern is whether or not the exhaust is spitting water or not and that takes not more than 5 seconds before I shut down based on the realization when I haven't opened the seacock. If you don't know whether or not the exhaust is spitting water almost immediately upon starting, your mind is being neglectful in my opinion. It's the very first thing that you have to confirm.

The last time I started the engine with the seacock closed was right after I changed the impeller. I was so frustrated that the exhaust wasn't spitting water that I didn't realize right away that I had closed the seacock to change the impeller!

I have started mine without opening the sea cock, but I can hear a difference in the tone of the exhaust...and immediately kick myself and shut down the engine until I open the valve. My exhaust is above the water though...
My Hunter 280 exited below the waterline, and it was much harder to hear it.

Greg

 

[jssailem]

I have also started my engine with the sea cock closed. One of the first things done once the engine starts is look over the stern and verify water is being discharged. Make it a habit and you will have a happy engine.

 

[kappykaplan]

One of the first things done once the engine starts is look over the stern and verify water is being discharged.

 

[RoyS]

I installed an electric boat horn to my engine temperature sender (switch). I can barely hear the original engine alarm module with the engine running. Horn will wake the dead and possibly cause a heart attack to the living but works exceptionally well as an over-temperature alarm.

 

[Ralph Johnstone]

look over the stern and verify water is being discharged. Make it a habit and you will have a happy engine.

Unless it's a Hunter with an under-water exhaust !

 

[jssailem]

The do you look over the side and look "very carefully"?

 

[Ralph Johnstone]

The do you look over the side and look "very carefully"?

Maybe if you had a mirror on a long stick. It's way under there.

Not very practical but perfect for "silent running" when sneaking up on submarines. From the side, you can't hear the engine running

 

[islandhop]

Maybe a dumb question but do most people close their seacocks when not on the boat. Since I bought my new,to me, hunter 376 I’ve been leaving them open. Also the engine intake I leave open. Maybe not a good idea?

 

[dmax]

Always close them, it could save your boat. The first boat I had with through-hulls almost sank a week after I bought it because someone didn't tighten up the clamp on the raw water hose when they winterized it (and I didn't close the through-hulls) - when I opened it up, water was over the floorboards and the bilge pump had drained the battery. I have closed the through hulls ever since.