Help. My boat Overheated

Hmmmm... MER is where I get my Yanmar engine oil from.... nice to know they also have the antifreeze.... Thanks.
 
I had the same problem with the same cause.....unfortunately I paid for a mechanic to come out and figure it out for me. The secondary issue is where the coolant went. My problem was a very slow leak at the water heater. Slow as in it took almost two years to run the coolant down. I also found the coolant tank level means nothing if you don't compare running/cold levels. Now I always check it cool and hot to make sure it's changing
 
If your antifreeze was low in the motor and the coolant recovery tank full you have a second problem besides the leak. The system is designed to run full, without any air in the coolant system, and as such it must have a place for excess antifreeze to go as it expands when heated. The radiator cap is supposed to release the excess volume through a pressure relief valve. A check valve in the cap allows the antifreeze to return to the system when the engine cools and the antifreeze contracts to normal volume.

If the system is not pulling coolant from the tank upon cool down you have a faulty radiator cap or blocked line. Check the line from the cap to the tank and make sure it is not pinched or kinked. I have seen old lines allow antifreeze out then collapse under suction and not let it return. Have also seen caps go bad.

That coolant recovery tank should have been sucked dry before the level in the engine system got low enough to cause overheating.
 
I thought the same thing. But... The mechanic told me that in cases of a slow leak far from the overflow tank, that it will not draw down the tank level. Which is why I never thought it was low....it always showed the same. I was over a gallon and a half short when he filled it back up, but the overflow tank still had coolant in it.
 
Hey there! Heck, this same darn thing just happened to us today! We were a gallon and a half low in coolant and just had the engine serviced two day ago. Temp alarm went off at 229 degrees, but fortunately we were very close to a marina. We let her cool down and went through all of the sea strainer, impeller questions, but we were just low...way low.

What is the typical cruising temp for the 6BY (R-29?). We weren't running hot - we pretty much had her at 8 knots the whole trip.

Question - were is the heater hoses typically leaking? I heard this was a recall issue and made sure to ask the Yanmar tech about it. He said we were good.

Another question: we didn't have Yanmar authorized coolant available, so used what we had to get home. Should we now have the entire system flushed?

Thanks.
 
You did not specify what you used, but assuming it was a good, high quality antifreeze it will be comparable with the existing coolant.
 
The coolant needs to be the long life coolant. It is usually pink in color, but that can vary by manufacturer. In any event the leaking hoses were right off the engine and are the ones that lead to the water heater. The other points of possible leakage are at the interior heater blower and at the point where the hoses enter the water heater. You may want to check the interior blower first, that and the hoses off the engine will be the easiest to check. I am not familiar where access is to the hoses on the 29. Perhaps someone else can help you there.

Let us know how it works out for you.

Mike Rizzo
 
Just use water for today - as was mentioned.
Then plan on changing the coolant. 363 hours is past time for fresh antifreeze.
Ok, so I'm the Philistine here :mrgreen: but all these dire warnings in the manuals that you better use OUR coolant or the ogres will come out from under the bed and get you make me go "aaarrrrggghhhhhh"
It's baloney.
It's an engine. It will operate just fine on water. However antifreeze (in the vernacular, Prestone) has some rather nice benefits. It lubricates the water pump. It raises the boiling point. It has additives that inhibit rust and corrosion. And it has buffers that keep the pH from going acidic.
Lessee, that's about it.
Oh wait, yeah I forgot. It keeps the water from freezing 😀

So wander into the nearest auto store, or WallyWorld, or even the Quiky-Mart and ask the clerk, 'ya got any antifreeze?' She will stop chewing her cud, errrr gum, momentarily, jerk her head in the direction of the stack of antifreeze jugs and go back to reading her dog eared copy of Bodice Ripper Monthly. (hey, it takes time to read fine literature, especially when you have to drag your finger along the sentence to keep from getting lost)
Now, the key question. The question of the day, the month, the year, of the universe fer Pete's sake - What Color?
Oh no! Not that question again 😱

Ya see, there is a loose standard for colors of antifreeze. Really loose. The girls at the Mustang Ranch have tighter standards. Ah well, I digress. Anyway, pick any major brand of antifreeze in any color and it will work.
There, I just let the cat out of the bag.
We have over a dozen engines here at the farm. Ranging from 1930's classic John Deere's to rather modern, high speed diesels. Keeping separate jugs in colors of the rainbow is not practical - and certainly not necessary. We have a standard color here - GREEN Like this guy :mrgreen:

Nothing wrong with antifreeze in other colors - but you sure as heck are not going to get Pink Foo-Foo juice (sorry Mike) at the West End in the Bahamas or in Fiji, or a whole lot of other places.
There are currently two oranges, two reds, green, dark green, yellow, blue, blue-green, clear and pink dye colors available
The orange and red antifreezes are an organic acid, not ethylene glycol base, and were designed for a 5 year service life in aluminum engines. I'm not familiar with Pink. The organic acids do not mix well with other colors (except for a short time as an emergency fix to get back to port)
The other colors signify different additive packages for corrosion inhibition, pH control, etc. etc. I won't go into the intricacies of Silicates.

So, when the time comes, drain the coolant, flush the engine with fresh water until it drains clear, then fill with a 50:50 mix of standard coolant - green or blue are usually readily available. Then change your antifreeze every two years and be happy - because your engine will.
 
Can't vouch for the facts but your reply was colorful. No pun intended! :lol:
Tuggin Aweigh
 
Nothing new to add but almost for sure it is your accessory hose connections leaking at one end or the other - heater, water tank, etc. seems to be "normal" with new boats from LLC - probably should be on a 20 hour break-in re torque list. Other than that, I'm learning as much as you from these posts!
 
Found the leak! As surmised, it was a hose connection at the hot water tank that was to blame, but over time had drip by drip almost emptied the engine, without affecting the level in the overflow reservoir. We tightened the clamps and wiped up all evidence of the coolant, then started the engine and let idle for a bit. The engine wasn't under tremendous load, but we are reassured that no amount of coolant was visible to the eye or touch after shutting down.

We're going to have the system emptied and flushed, then refilled with Yanmar coolant as I discovered I accidentally added some other "pink" coolant that contain ethanol, so don't want that to remain in there more than a short period. It got us home, but now time to go!

Thanks, as always, for the advice and quick tips.
 
If you really want to ensure that you have no other leaks, pressurizing the system would be the best way. Pump it up and wait to see if you loose pressure. It won't tell you where the leak is, but at least you know to keep looking.

By the way, the overflow tank is what it is, an overflow tank. It is not an indicator if you have enough fluid in your cooling system. The indicators on the side of the tank are misleading and should not be used as a guide. Opening you cap is the only way to check on your antifreeze level.
 
Dennis
( Jim, Barry and others).
I really appreciate when people post these kinds of issues. I am less than astute when it comes to mechanics, electronics and the likes! I study this stuff on this site in hopes. I can remember should/when it's my unlucky turn! Thanks!!
Garry
 
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