Anti Freeze keeps getting low

[azubair]

I have an Iveco 120 hp engine on my boat. I have noticed that after running the engine for sometime, the anti freeze level drops and i have to top it off. This happens every few weeks. The engine is raw water cooled with a heat ex-changer. No leaks in the cooling system that i can discern. Engine has never shown signs of over heating. Any thoughts that the experts on this forum can share with me about this issues would be very much appreciated.

 

[SteveK]

Worst case, you need to replace the heat exchanger or at least take it to a rad shop for testing.
But, the coolant (antifreeze) can be getting past the rad cap. Unless it has a reservoir it will end up in the bilge.
BTW, when you have a heat exchanger raw water cools the fresh water/antifreeze in a fresh water cooled engine.

 

[bgillroy]

If it's an le120 your gasket between discharge end xhaust manifold and exhaust elbow may be failing. You may be shipping a ntifreeze out withdraw water exhaust.

 

[bgillroy]

Make sure petcock on forward end of exhaust manifold is closed tight to your feel. Don't use tool.

 

[bgillroy]

Everyone thinks HE. Likely a hose leak. Head gasket leak is remote. If HE is newer having been replaced normal service life, suspect exh gasket discharge end.

 

[psneeld]

Does you engine have an expansion tank? Recovery tank?

If so, and you are topping it off and don't have a recovery bottle, it could just be dumping ito the bilge. Any sign of coolant there?

 

[C lectric]

To what level do you fill the heat exchanger with antifreeze/coolant?

If the engine is cold and you fill it to the neck where the cap resides then when the engine runs and heats up the coolant will expand. That expansion will cause the antifreeze to be spit out into the bilge unless you have a small tank or bottle [ recovery bottle] of a litre to 1.5 litre or a bit more that is connected to a nipple on the side of the heat exchanger cap neck that runs to the bottle.

If you do not have the small bottle then you are probably overfilling the system and it will continue to spit coolant out.

Is there a nipple on the cap neck side with a hose attached leading to the bilge? If so then put the hose end into a bottle , secure the bottle, and next time you are out then check the bottle for coolant. If there is coolant then you are overfilling it.

Either leave the coolant level down from the cap neck about 1.5" [~ 36mm]
or 2" [~50mm] . You may have to experiment a bit to learn the level the engine needs to stop spitting into the bilge.

I would also suggest that you go around and check EVERY hose connection that the clamps are tight. Not cranked hard but well snugged. All hoses can take a set, shrink, over time thus releasing some of the clamp pressure.
Any looseness can allow coolant to escape.

 

[utclmjmper]

In aviation we called that "chasing a quart" as it pertains to oil,, it works the same way with coolant systems when the expansion is not allowed enough space for the expansion to occur ..>>>Dan ( It's not getting low , you just think it is.)

 

[Spinner]

Does your coolant also heat your hot water tank and or a “red dot heater?” Check there for leaks!

 

[willpep]

I had a similar problem on my Yanmar. After much trouble shooting including a pressure test found that it was my radiator cap assembly. Small leak where the cap assembly attached to the heat exchanger. Under pressure it would slow leak and boil off since the engine was hot. Hope this helps. Cheers

 

[Lepke]

The coolant pressure is higher than the raw water. So a pin hole leak in the exchanger will put coolant into the raw water and out the exhaust.
If you don't find something else, I'd have the heat exchanger pressure tested.

 

[azubair]

Thank you all. I will follow up with all your suggestions. I suspect the HE. It has never been serviced since the boat was commissioner in 2010. Has been on my to-do-list. There is a bottle attached to the Anti-freeze system. No discernible leaks any place else. No anti-freeze in the bilge. It is not a problem topping of the fluid, more of an annoyance. But i wanted to get your opinion if this could be a symptom of a potential larger problem.

 

[quinsky]

Recently had the same issue on one of my John Deere 6068s. When I bought the boat I noticed a small amount of coolant pooling near the front of the heat exchanger where the coolant inlet and exhaust are located. I replaced the exhaust manifold gasket and thats when I had to start adding coolant every time I ran the engine. There were no obvious signs of a leak. I considered all the afore mentioned problems but before I called a mechanic I decided to check the HE bolts. Sure enough they were all loose. After tightening them the leak stopped. I assume the coolant was evaporating before it reached the bilge.