Running hot in Caribbean

[boatman61]

Originally Posted by stormalong

Huh? Do you mean the tube stack in the heat exchanger?

No.. the rectangular block that bolts on on the opposite side to the injectors..

[jr_spyder]

Thanks all, and a few updates. I had a spare temp sensor onboard so changed it. No change. Also temp read with ir thermostat within a couple degrees of gauge, so neither the gauge nor sender are a problem.

As for flushing, Barancle Buster, Rydlyme and white vinegar basically all do the same thing but at different potentcies, and maybe with some other different benefits. Basically they get built up crud out of heat exchangers. I was impressed at what came out of mine after the prescribed time of cycling the fluid through a loop of my raw water heat exchanger, transmission oil heat exchanger, and bucket and hand pump. But it didn’t help the temp problem. Incidentally I did the same flush through my two air conditioner heat exchangers, got crud out, and definitely saw I improvment in their efficiencies.

Not wanting to consume my cruising time with this I called a diesel mechanic a the local yard in Antigua. He came over and really seemed to know his stuff. After going over all my efforts and results, and checking a few things, he still believes the problem is on the raw water side with not enough flow. In particular he is suspicious of the elbow where the raw water is injected into the exhaust stream. Mine is quite old. He said inside the elbow there is a sort of nozzle that mix’s the now heated water and the exhaust. Over time this can get rusty and clogged up, restricting flow. Seems plausible to me. I’ll take that apart tomorrow.

Stay tuned...

[Cadence]

Two thoughts. A thermostat or possibly growth on your raw water intake.

[jimbunyard]

Due to the progressive nature of the problem, I'd say you're on the right track with the exhaust elbow. 1600 hrs is a lot for that particular part, which many consider a 'consumable' (though the rate of 'consumption' is very slow indeed...)

A partially clogged elbow, or one with some channels clear and others blocked can cause overheating even if it seems to pass enough water through the system because, in some system designs, excess heat can build up as in a heat sink and be telegraphed gradually back through the rest of the system. I even suppose that, with engines running at the higher end of the temperature envelope in tightly enclosed engine rooms, the increase in ambient temp from a single overheating part or section of an engine could push the engine into an overheat mode, but maybe that's veering too far into theory...

[NYSail]

When was the last time you flushed and changed coolant in engine? That stuff does go bad and a lot of crud does build up. I remove the thermostat and flushed my new to me engine this year and even on the third flush crud was still coming out. The engine, a yanmar 4JH4E has Only has 550 hours. Put
New thermostat and fresh fluid and dropped operating temp.

[jr_spyder]

So I’m embarrassed to admit I don’t know the last time the coolant was changed. I’ve had the boat 6 years and have put 300 hrs on the engine in that time. The previous owner had a blank check with his yard and they did all maintenance as needed. So things were done right but not sure when. The coolant looks clean and bright, but not a bad idea just to change the coolant now and keep better records.

That said I haven’t done this before and I’m having a heck of a time seeing how the coolant gets drained out, and all my manuals for the engine don’t help. In a car you just drain from the bottom of the radiator of course, and that’s the low point of the cooling system. I have a drain petcock on the heat exchanger but that is no way the low point for the system. What am I missing?

[four winds]

I don't know your engine.

But typically there should be a drain valve somewhere low on the block. Try looking just above the oil pan flange on the side of the block. A position that would be at the lower level of the water jackets.

[NYSail]

My first boat had a Westerbeke and had a drain cock low on the engine.... search and you should eventually find it. The problem with old anti-freeze is that it may look good, however is not doing its job. The marine environment puts different strains on the stuff.... Long time storagae without use is one that causes the stuff.... so I hear... to breakdown and not be as effective and get a bit gooy. Like I said, I removed my thermostat, replaced housing and flushed engine 4 times before I added new coolant. I drained, added water and let engine heat up... drain, add, heat up. By 4th time water was a bit cloudy but no more "crud". I took this time to replace all the hoses as well. Love Shell Rotella EL coolant.... good stuff and don't want to mix different products.

Good Luck!

Greg

[hugosalt]

Exhaust elbow is high percentage suspect. Would be good idea to monitor/record raw water output before and after any cleaning at several different rpm levels. (and keep as base line for future).
If possible when removing exhaust elbow, remove exhaust manifold (what boatman
referred to) and take a look for any build up (carbon?). Will need new gasket.
Not familiar with motor, may have to remove some bits but usually easy job for you
or mech. Luck!

[jimbunyard]

Also, if your heating problems are marginal, running straight water can stop or moderate them. (don't think you have to worry about freezing in the Caribbean)

Water has about 30% better thermal conductivity than 50/50 antifreeze/water.





Antifreeze does have some anticorrosive and lubricant properties, so for extended running with pure water, an additive, such as the one shown below, is generally recommended. For short periods (2-3 months? [I've gone a couple years]), pure water alone is fine...

[Cadence]

Originally Posted by jimbunyard

Also, if your heating problems are marginal, running straight water can stop or moderate them. (don't think you have to worry about freezing in the Caribbean)

Water has about 30% better thermal conductivity than 50/50 antifreeze/water.





Antifreeze does have some anticorrosive and lubricant properties, so for extended running with pure water, an additive, such as the one shown below, is generally recommended. For short periods (2-3 months? [I've gone a couple years]), pure water alone is fine...

Water alone with boil quicker. It is a misnomer that antifreeze is only to prevent freezing.

[Sea Life]

Having helped other boaters on several occasions in the Caribbean with similar issues. My advice....don’t assume water flow is adequate, it will look the same at 50% as it does at 100%, only with loading and delta T across exchanger can you hegin to determine. Pull hose off and place in 5 gallon bucket and time gpm. Compare to specs. You will he surprised by how much water is supposed to flow. You could also suck out of bucket for gpm reading, comparing the two will also show problem on discharge or suction of raw water pump. For instance a small 3 cyl 6kw NL gen is rated at 5gal/min.

Good luck. FYI, I’m in Jolly Harbour currently. I’ve been known to help for rum

[jimbunyard]

Originally Posted by Cadence

Water alone with boil quicker. It is a misnomer that antifreeze is only to prevent freezing.

While this is true, the fact is that pure water will provide more efficient cooling.

Also, with a 10 psi pressure cap, the boiling point of water alone is 240F, which is above the 223F provided by 50/50 AF/water (though that is at atmospheric pressure; since it's a moot point I didn't try and find the BP for AF/H2O at 10 psi).

In any case I wouldn't want to run an engine over 212F anyway, due to potential oiling problems at that temp, but hey, that's just me...

[bensolomon]

I had a similar issue in my boat. I did the things you did plus:

Look at the hose that brings in the raw water to your engine, as well as dive the raw water intake. I had growth in the bottom of the hull in the raw water intake hole. I also pulled off the hose and looked in it for obstruction to flow.

I also completely replaced the raw water pump. I replace my impeller every year, but was still having issues until I replaced the sea water pump.

Also, I put on a new mixing elbow, but.....the issue was the little nipple that accepts the cooling water into the elbow. That gets plugged, and ends up being the limiting factor.

Good luck!

[jr_spyder]

Damn, I just wrote a very long update and when I submitted it the forum told me my token had expired and all my input was lost! Too pissed to write it all again. Sorry. And it was full of brilliance...

My conclusion, like others, is I’m leaning towards the exhaust mixing elbow being the problem restricting raw water flow. The elbow is showing other signs of deterioration with an exhaust leak starting a few weeks ago from the flange connecting to the exhaust manifold. Part of the metal making the flange has been eaten straight through. Big clue!

Thanks for all this input and support. Great community here, as usual.