Volvo Penta KAD300 DP-G fake temp alarm

[pentator]

Hi all.

Have a single KAD300 hooked to a DP-G drive in a 2005 planning hull cruiser.

Engine is just reached to 609 hours, clean bottom, drive, props, impeller changed last year and did 95 hours, heat exchanger, oil cooler, power steering cooler and aftercooler cleaned 3 years/280 hours ago also turbo and compressor.

Last summer while cruising on a cross/beam sea on plane jumped over a wave and suddenly overtemp alarm went off, also the overtemp indicator flashed on the alarm panel, temp gauge showed 100C. Immediately pulled back the throttle to neutral and temp decreased to 85C then hit the throttle but engine revs limited to 2200.
Stopped and restarted and engine ran without over temp. 15 days later from this incident same happened again since I jumped over a beam sea wave. Checked the impeller and it was fine. Also I'm a year round boater and have never had an issue like this until one month ago.

I run on plane at 3000rpm reaching 18,5-19 knots, trim tabs fully retracted and drive trim -2 to +2 according to sea and load conditions.


One month ago while on plane cruising around an island where I spend my summers, turned to port 30 degrees via autopilot and overtemp alarm went off BUT temp gauge was at 85C (which is the degree of 1st thermostat and at 92C 2nd thermostat opens) pulled back the throttle jumped in to the bilge and checked the seawater components/hoses buy IR temp gun and there is no real overheating also outdrive was intaking and discharging water and impeller housing was cold.. Hit the throttle and couldn't pass 2200rpm. Stopped and restarted then no problem.

This fake overtemp problem arised last five consecutive days where I was on the boat, alarm wents off after a few minutes of getting on plane on a wavy day, and once happened at the marina entrance to pass the other boats I hit to 3500rpm and then happened while I was cruising 20 minutes problem free. Yesterday I uninstalled the impeller and it was spotless and installed it back.

Talked to my mech and he thinks this is not a mechanical issue and would be electrical and he’ll be onboard at the weekend to hook a vodia . I’m guessing that while jumped over the waves the temp sensor in the exhaust elbow loosen or moved a bit or broke etc and cause false alarm then pretends the engine as there is real overtemp.

Forgot to mention that EDC control panel D button gives 1.1 code which means there is no problem, but I wonder if really an overtemp occurs will it show a trouble code or if I’m having an electrical problem shouldn’t it blink different from 1.1?

Hope someone can shed some light to my problem.
Thanks in advance.

 

[alldodge]

Read your thread yesterday and was hoping someone with knowledge would come in. I can say one thing you explained the issue very well and my limited info on the electronics of your engine, I would lean toward an electrical issue. Have had a similar issues with Mercruisers and seawater pressure switch giving the ECM a fault when there was none. When the pressure on the seawater pump is reduced the ECM retards the timing. If the engine is turned off and restarted the problem goes away. Either way chasing down a gremlin is tough going.

Hope someone comes in with more knowledge

 

[pentator]

Read your thread yesterday and was hoping someone with knowledge would come in. I can say one thing you explained the issue very well and my limited info on the electronics of your engine, I would lean toward an electrical issue. Have had a similar issues with Mercruisers and seawater pressure switch giving the ECM a fault when there was none. When the pressure on the seawater pump is reduced the ECM retards the timing. If the engine is turned off and restarted the problem goes away. Either way chasing down a gremlin is tough going.

Hope someone comes in with more knowladge

Thanks AllDodge,

Forgot to add that I added approximately 1 liter freshwater to the coolant expansion tank where I filled fully antifreeze, and it's spread into the bilge so antifreeze level was/is correct .

Ran the boat today 15-20 minutes on plane in a half meter chop/wave at 3000rpm north and south, cross and beam sea and haven't the overtemp alarm went off.

Before the trip I did my regular daily/weekly maintenance such as checking the acidity level of the wet cell batteries, toping off the electrolyte, measuring with multimeter batteries, battery cables, alternator and starter both engine on and off, draining the separ diesel/water separator and purging the fuel system. All were fine but I checked them since I'm thinking that I have an electrical problem and if my batteries are defective and cause but they are fine/2year old.

Also before the trip I sprayed liberal amount of Boe T9 to the all electrical components/sensors on the engine, back of temp gauge and alarm panel cables as if they are corroded and causing false/fake overtemp alarm

Up to now.no alarm but lets see tomorrow.

Fingers crossed.

 

[pentator]

Update:

Ran the boat yesterday on plane at 3000rpm half an hour (15 minutes and a few hours later return trip 15 minutes), boat ran great seas were flat at first ride but were choppy at the return trip, had no alarms.

I'm thinking that if spraying T9 did some magic and sorted the problem, or jumping over the waves caused the two or least second 92C thermostat stuck closed and coolant was not cooled by the heat exhanger/sea water.

I'm leaving it as it is right now and if I have overtemp alarm again at the weekend then will uninstall the thermostats and boil them in a kettle at home to see if they are opening or not regularly.

 

[alldodge]

Sounds like a good plan, sure is a strange one for sure. Thanks for keep us updated.