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Re: Coolant Loss Mystery
Posted: July 31st, 2017, 8:32 am
by bud37
Imo ,if you were burning it there may be that sweet smell in the exhaust gasses......in regards to the heat exchanger, I guess so long as you have water flow and enough coolant in the engine you would not overheat until you got to the low coolant point. If you have one ,double check your temps with an IR temp gun.
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 9:48 am
by km1125
I doubt you're losing it out the heat exchanger.. the raw water should have pressure in it and would fill rather than empty the heat exchanger.
Time to do a pressure test!! If you're using a polypropylene glycol based coolant rather then ethylene glycol, you might not notice that "sweet smell" in the exhaust.
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 10:26 am
by tomschauer
could be in the main exchanger or the tranny exchanger. If its going that fast it should be fairly easy to find with a little pressure.
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 12:00 pm
by km1125
If it's the tranny exchanger, wouldn't the tranny be full of water by now?
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 12:08 pm
by tomschauer
Actually the trans fluid would be gone as the trans pressure is higher than the water pressure. My bad.
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 1:08 pm
by km1125
I don't have closed cooling.. but to the oil and trans coolers get fed with raw water, or the closed cooling system water?
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 1:38 pm
by tomschauer
I have closed cooling. I assumed they are fed by the closed system, but I never traced it to verify. I will check out this weekend.
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 1:50 pm
by bud37
The pressure in the engine coolant would be far higher than the raw water side, there may be some incidental pressure but it would not overcome a leak from the engine side IMO . Actually there may be another potential leak point in the exhaust manifolds if they have engine coolant passages in them with this being closed cooling......just some ideas, I also think there will have to be some pressure testing done.
I wonder if one were to get a sample of the exhaust discharge water, could that be tested for engine coolant ( anti freeze )??
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 4:07 pm
by km1125
bud37 wrote:Source of the post The pressure in the engine coolant would be far higher than the raw water side, there may be some incidental pressure but it would not overcome a leak from the engine side IMO . Actually there may be another potential leak point in the exhaust manifolds if they have engine coolant passages in them with this being closed cooling......just some ideas, I also think there will have to be some pressure testing done.
I wonder if one were to get a sample of the exhaust discharge water, could that be tested for engine coolant ( anti freeze )??
The coolant side will only have pressure from heating up... once that leaks off there's no more pressure unless you're hitting the boiling point. The raw water side should have at least 5psi, shouldn't it?
Perhaps the "best" place for there to be a problem would be the block-off plates between the manifold and riser. This would be the easiest fix. A pressure test would tell you though... you might even be able to hear it leaking. You should be able to isolate the manifold pretty easy to to test each one individually.
Re: Coolant Loss Mystery
Posted: July 31st, 2017, 8:31 pm
by bud37
nautiyachti wrote:Source of the post I have an 06 Carver with twin 8.1 Liter (496's) engines. I recently noticed my port engine coolant reservoir was empty so I filled it (1 jug) ran the boat for around an hour and it is empty again. The mystery is that the engine is not showing signs of over heating, no coolant in the bilge, no white exhaust smoke indicating it's being burned off? I'm stumped. Sure I could be losing it out the heat exchanger but wouldn't I be overheating?
Here could be a good read, some diagrams and testing procedures for you, maybe not the same engines as yours but I believe the theory is the same.....
http://www.boatfix.com/merc/servmanl/18/18b6r2.pdf