Strange Westerbeake overheating problem

[FAST FRED]

I would let the sea water run free before the exhaust elbow , to attempt to judge its volume . Same before the heat exchanger and after , to find a restriction.

but during a load test with the boat tied in the slip and running in gear at 1700 rpm the temp went to nearly 200 deg F in less than 10 minutes.


IF the prop is the correct prop for the boat this is a LOUSEY test, and SHOULD overheat the engine.

Reason is the prop is not pitched for still water , probably for about a 6K speed thru the water.With zero water speed the prop has twice as much pitch as it should and will usually blow black smoke.

A nice touch , after you find the problem is a 1 inch Y strainer after every impeller pump.

Impeller chunks can be found and removed in an instant.

Works for me,

FF
Re

[Heatex]

My business manufacture and supply heat exchanger cleaning kits specifically designed for use with boat and marine shell & tube heat exchangers.

Full details are available at our website www.heatexchangersolutions.co.uk

[drmiller100]

another thing you can do is use IR meter to figure out the problem.

hot engine coolant into exchanger, and hot coolant out temp means exchanger isn't exchanging. Then look at raw water, and see if water going in is ambient and water coming out. If both are warm, probably not enough raw water flow.

If raw water is cold going in and out, and engine coolant is hot going in and cool going out, then it is engine coolant flow.

[tranmkp]

IR thermo is a good idea - my issue was this -



someone forgot to take a rag out of the coolant manifold when the engine was painted. Clue was the loack of water being discharged. With a boat - anything that COULD happen WILL happen. After rag removal, also removed that little brass diverter for a HWH as I dont have one - Boat runs 180.

[paulhille]

I agree, it is a fact if you use all anti freeze you can run hotter as the transfer is not a good with too much , I recomend you try a 60/40 water to anti freeze mix, with a good cleaning also. Put a new 180deg thermostat in, check your impeller and you should be good. Red

[tranmkp]

after installing new heat exchanger/new coolant /thermostat engine runs well - however at high rpm < 3000, the exhaust hose begins to smoke - which means that the temp is over 250 degrees - I have pulled the elbow and checked water flow through the nozzle, all seems well. Is it that the velocity of exhaust gas is so fast that it is just turning the water to steam? Of course I suppose it is a lot hotter also. Lower rpm is not an issue - Should I just install Hi Tem Silicone hose and not worry?

see elbow

[paulhille]

It sounds like you found the problem, 3K seems hard to run youe engine. What is your normal operating RPM for say 5 knts?. My boat is slow, I run at 1800-2000 K, and get about 5kts. I look at it like, if I was to run at 3000 rpm I might only get 1/2 knot, to me its not worth the wear and tear or the xtra fuel. RED

[tranmkp]

about 1900 for 7knts

3100 will produce 14.5 knts

sure a lot more fuel - I just want to try to get it right - you never know when you might have to go a little faster...

[paulhille]

Wow you are fast, what engine size are we talking about, in what make and size boat. Where are you located? REd

[tranmkp]

Its a 1986 Albin 27 aft cabin - at 14.5 it is overpropped - will only get to 3100 rpm when the 70hp engine redlines at 3800rpm.

[paulhille]

You have 70HP?, wow, how heavy is your boat? I have a Jeanneau 38,around 20K lbs, with a 30 hp, man you could waterski!. I am in the raritan bay, Keyport where is your boat.

[tranmkp]

Texas - Galveston bay

Albin 27 is a little trawler, not the Albin 27 sailboat. I weigh in at around 8k.

[philSweet]

My first guess would be what KenJ said about the elbow. I've got a universal 5424 in Florida, which may be nearly the same motor depending on age. Another common problem relating to backpressure on the freshwater side is the presence of a hot water heater plumbed in series. Several factories did this. Produces lots of hot water at the tap, but overheats the motor if the sea is above about 70F. The solution for warm climates is to remove the water heater from the main loop and reinstall it in the tstat bypass loop. Cut the little 3 inch bypass elbow and adapt that to the waterheater. Slower to heat the water, but how much hot water do you need in the Bahamas in the summer? I got about 400 more RPM when I did this.

[baeckmo]

Originally Posted by tranmkp

after installing new heat exchanger/new coolant /thermostat engine runs well - however at high rpm < 3000, the exhaust hose begins to smoke - which means that the temp is over 250 degrees -

Of course your hose is going to burn with this setup!!!! The skin of your elbow is not cooled; there is just a water inlet to its center. You will have no cooling effect on the surface where the hose is clamped, thus the smoking. There should be an additional jacket, allowing cooling water to enter along the periphery close to the hose stub. The first half meter of hose (if not all the way) has to be increased one size in diameter.

[tranmkp]

thanks for the insight on this - I would never thought. To increase size I will have to make some sort of collar, any ideas? Would not the over size hose burn aslo?