Official 2003.5-2008 340 Sundancer Thread

My vote is sensor/sender. They go bad. Try swapping with starboard sensor and see if you get he same readings or if starboard acts up.
 
i have the south bays on there, yea the more i think about it, it has to be the sensor. what is your water pressure at idle? im reading about 4psi on the starboard side.
 
swapping them is a good idea, but if im gonna maneuver my ass down there to pull it out, im just gonna put a new one in hahaha
 
I probably need to replace mine. I get 1.8 on port and 4 on starboard at idle. Seeing as I’ve replaced manifolds, water pumps, belts, and impellers all in the last few months (water pressure is still the same as well as engine temps both steady at 165 during cruise), I’m thinking it’s got to be the sensors.
 
yea i hear ya, i just went out to the boat and turned the switches on to look at my vessel view without starting the motors. the water psi on starboard is zero. but its reading 34psi on the port. both motors not running. so there it is, definitely the sensor. maybe see what your sensors are reading with engine shut off. maybe they are bouncing around or reading pressure when they shouldn't.
 
yea i hear ya, i just went out to the boat and turned the switches on to look at my vessel view without starting the motors. the water psi on starboard is zero. but its reading 34psi on the port. both motors not running. so there it is, definitely the sensor. maybe see what your sensors are reading with engine shut off. maybe they are bouncing around or reading pressure when they shouldn't.

They both read zero off. Ok but wait a sec ...I don’t think the sensors are on the water pumps. At least not on mine. I was down there 2 days ago replacing my port pump and there’s no sensor/sender as Kevin’s pic indicates. Possible they’re on the oil cooler?

Here’s pics (both sides) of my port side water pump..just two drain plugs. Hmmm. This requires more research.

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Did a little research. Not sure about you guys, but on mine pretty sure the water pressure sensor is here on the transmission oil cooler. Will confirm tomorrow

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Holy crap I hope that’s the same on mine, I’ll unplug it and see what it’s reading on the vesselview with motors off, thanks for the update
 
I have a sensor there so I’ll see if it’s the one. That would really make the job a lot easier
 
That's weird. That was a screen shot image right from the Merc 30 Service Manual. Maybe they relocated it. Sorry for any confusion.

-Kevin
 
no worries kev, i called mercruiser this morning, if u have a transmission like we do they relocated the sensor to the cooler. makes the job nice and easy. just ordered mine 5 min ago. south shore marine had it in stock.
 
hey there was a thread recently about the back vent covers that someone lost or had stolen. i checked mine the other day and i have one side coming loose. anybody reseal this? what did u use? i was thinking 4200 marine sealant.
 
hey there was a thread recently about the back vent covers that someone lost or had stolen. i checked mine the other day and i have one side coming loose. anybody reseal this? what did u use? i was thinking 4200 marine sealant.
Hi I did mine a few months ago.I used 4200. Worked out well. I used sand bags to hold the vent down till the 4200 set up.
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Mprod, I see you have double clamped the pressure side hose on your raw water pump. Has it always been like this or something you have done? I only ask as mine are only single clamped.
 
...they relocated the sensor to the cooler. makes the job nice and easy...

Maybe the should have left the sensor and relocated the pump to make changing the impeller easier ;).

I get a lot of my local stuff over at Freeport Marine. I have an account over there if you need anything pricey.

-Kevin
 
thanks for the heads up kev, maybe one day i'll upgrade electronics and go through them. . i agree man the impellor housing on bottom of motor is ridiculous.

as for the double clamping of hoses, its my understanding that any hose below the waterline of the boat should be double clamped. any hoses that start to leak below the waterline will sink the boat.
 
...maybe one day i'll upgrade electronics and go through them...

I have plenty of experience there. I just did a full upgrade to Raymarine Axioms (Dual Head) with Navionics and Quantum Radar and networked. Absolutely awesome setup. Last phase is the Smartcraft to N2K gateway. If that works well I may replace the tachs and speedo for with another axiom for engine data.

I will be posting my write up in the next week or so.

Next year will be the VHF. Want N2K and AIS (for the fun of it - its useless in the GSB) so leaning towards a Ray70 or Lowrance Link-8 for that.

We are also fabricating our own panels now for the radar and center helm. Should have the CNC programming for the gauge panel within the next couple of weeks too.

Looks like we're finally going to have a nice stretch of weather and our kids schedules are starting to interfere already.

-Kevin
 
Wow that sounds awesome, would love to do the axiom with radar. Maybe even an autopilot would really be nice for me. What u think my cost would be for all that?
 

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