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01-10-2015, 15:28
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#1
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Registered User
Join Date: Mar 2011
Location: fl- various marinas
Boat: morgan O/I 33' sloop
Posts: 1,447
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Exhaust water temp alarm?
my kabota diesel tends to overheat at 2200 rpm and up. have investigated just about everything. I'm wondering if an exhaust water temp alarm might be the early warning I need rather then staring at the engine temp gauge. good idea or bad?
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01-10-2015, 15:47
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#2
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Registered User
Join Date: Apr 2011
Posts: 2,492
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re: Exhaust water temp alarm?
Which version is it, and what diameter is the heat exchanger? Universal engines with the 2" heat exchanger tend to display this symptom, for the simple reason that the heat exchanger is inadequate.
I upgraded mine to a 3" version, and can now run at full power all day, at 170F. Previously the limit was about 2K rpm, to keep the temperature under 185.
__________________
Bristol 31.1, SF Bay.
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01-10-2015, 15:54
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#3
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Registered User
Join Date: May 2011
Location: San Diego CA
Boat: Liberty 458
Posts: 2,205
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re: Exhaust water temp alarm?
If you log the temps in and out of both cooling circuits you'll find the culprit. I use a handheld IR temp gun. Cheap and non contact.
Overheating can be triggered by flow that is too slow or too fast. Heat exchanger capacity, corrosion buildup, collapsed hose (on the inside), low fluid level and faulty thermostat are all candidates too. All these can be diagnosed from logging temps.
If you find that both circuits have a relatively even temp delta but temp keeps rising then a bigger heat exchanger is probably a good solution.
Sent from my SM-N900T using Cruisers Sailing Forum mobile app
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02-10-2015, 07:44
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#4
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Registered User
Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,108
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re: Exhaust water temp alarm?
Make sure the engine is actually overheating by directly measuring the thermostat housing or similar coolant area with an IR gun. It is common for gauges to be wrong - and they often start creeping up in measurement as they go bad - when they rail on high.
Mark
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www.svreach.com
You do not need a parachute to skydive. You only need a parachute to skydive twice.
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02-10-2015, 07:55
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#5
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Registered User
Join Date: Feb 2007
Location: Southwestern Yacht Club, San Diego, CA
Boat: Searunner 40 trimaran, WILDERNESS
Posts: 3,175
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re: Exhaust water temp alarm?
I installed an Aqualarm flow switch to the output side of my seawater strainer, prior to the seawater impeller. If a plastic bag blocks the seawater intake, or the impeller throws a blade, I have an early warning that the engine will shortly overheat. I have also rigged an LED light and a piezoelectric buzzer above the engine temp gauge to reinforce this message. Plus, I use the idiot light switch with a different color LED and different frequency buzzer to tell me when the actual temperature has gone up to a nasty point. These allow me to know that things are getting awkward even if I'm off watch and blissfully dreaming. Obviously, these are powered by the engine ignition switch.
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02-10-2015, 07:55
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#6
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Registered User
Join Date: Oct 2003
Location: Cruising
Boat: Ebbtide 36 steel cuttter, 11m
Posts: 34
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re: Exhaust water temp alarm?
I recently fitted an exhaust temperature alarm to my Beta 50. I have had no overheating problems, but experienced the advantages of an exhaust temperature alarm on a gen set while doung a delivery. I wrote a short article for the Beta forum. Mr Feinbaum, the Beta guru agrees that it is a good idea. The cost was about $ 60, and 1 hrs work. Cheap insurancw
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02-10-2015, 09:14
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#7
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Registered User
Join Date: Feb 2011
Location: Meandering about the Gulf of Alaska coast [NNE Pacific]— where the internet doesn't always shine... [Even Elon's...] Homeport: Wrangell Island
Boat: Nauticat 43 [S&S Staysail Ketch]
Posts: 1,671
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Re: Exhaust water temp alarm?
Quote:
Originally Posted by Dave22q
my kabota diesel tends to overheat at 2200 rpm and up. have investigated just about everything. I'm wondering if an exhaust water temp alarm might be the early warning I need rather then staring at the engine temp gauge. good idea or bad?
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Hi Dave,
There was a similar thread back in July this year where I detailed a cost-effective approach ($10 waterproof sensor strapped to the outside of the wet exhaust hose...)
See: http://www.cruisersforum.com/forums/...ml#post1880489
In case that is useful to you.
Cheers!
Bill
__________________
SV Denali Rose
Learning every day- and sharing if I can.
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02-10-2015, 09:20
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#8
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Registered User
Join Date: Mar 2014
Location: Anacortes
Boat: previous - Whitby 42 new - Goldenwave 44
Posts: 1,835
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Re: Exhaust water temp alarm?
Our boat has high temp exhaust alarms on both the genset and the Perkins main engine. It rings a loud bell. It also has a raw water flow sensor, and a high temp oil sensor, all to the bell.
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02-10-2015, 12:49
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#9
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Registered User
Join Date: May 2008
Location: Nova Scotia until Spring 2021
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,976
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Re: Exhaust water temp alarm?
Quote:
Originally Posted by Bill Robinson
I recently fitted an exhaust temperature alarm to my Beta 50. I have had no overheating problems, but experienced the advantages of an exhaust temperature alarm on a gen set while doung a delivery. I wrote a short article for the Beta forum. Mr Feinbaum, the Beta guru agrees that it is a good idea. The cost was about $ 60, and 1 hrs work. Cheap insurancw
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There is a lot of good advice here so far.
I have a Beta 60 and no overheat issues so far, but I agree that an IR temp reading of the circuits will rule out an obvious fix, AND that an exhaust overtemp alarm is good for things like taking a fish or a plastic bag over or into the intake, enough to restrict flow and cause an overheat, but not enough to actually kill it.
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02-10-2015, 12:50
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#10
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Registered User
Join Date: Apr 2011
Posts: 2,492
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Re: Exhaust water temp alarm?
Waiting for an answer to my question about engine model.
__________________
Bristol 31.1, SF Bay.
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02-10-2015, 15:37
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#11
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Registered User
Join Date: Apr 2010
Location: Tasmania
Boat: Swanson 36 in Australia Bavaria 42 in Med
Posts: 340
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Re: Exhaust water temp alarm?
Probably not but possible that a raw water impeller has collapsed at some time and the separated fins have gone downstream somewhere and caused a partial block in the exhaust water flow.
For this reason impellers should be replaced periodically as a matter of course. Every couple of years maybe for the average yacht. More frequently for high annual hours.
Disclosure. I am as guilty as hell on not doing this, but will in future.
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03-10-2015, 06:41
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#12
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Registered User
Join Date: Mar 2011
Location: fl- various marinas
Boat: morgan O/I 33' sloop
Posts: 1,447
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Re: Exhaust water temp alarm?
thanks for all the good responses. I'm sold that it's cheap insurance with no downside. will post conclusions after a few months of use. I've also ordered a temp gun to double check the gauge readings.
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03-10-2015, 07:18
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#13
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Registered User
Join Date: Feb 2007
Location: Southwestern Yacht Club, San Diego, CA
Boat: Searunner 40 trimaran, WILDERNESS
Posts: 3,175
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Re: Exhaust water temp alarm?
The temp gun has other cool uses as well: Shoot it at a bronze thruhull to get ocean water temperature. Shoot it at the cutlass bearing to determine, without getting on your hands and knees if it's overheating. Play it over the connectors and breakers inside the electrical panel to see if anything is overheating. Use it to check the oven thermostat. I love mine.
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