Alarm on port side...baffling mechs

[PatrickHays]

Just trying to give as many details as I can think of...I am posting this to some boards to get any suggestions I can get.

I have an alarm going off from the port engine after cruising for about 5nm (here's a link to the video) on my 2001 Sportcraft 3010. Dual inboard Mercury 350, 300 hp engines, 5000 series Velvet Drive V transmissions ~250 hours on the boat.

Boat runs great at all times. No slipping, crunching or grinding, no problem shutting down and starting up during the alarm. The alarm does not sound when the key is turned, but once it starts alarming it will stay on in a neutral idle as in the video, but not just by turning the key prior to starting.

It alarms only after running at 4000 rpm ~ 22Kph for some time. It doesn't happen every time after 5 miles but if it does, it takes hours (3-5) for the alarm to not sound when in either gear or neutral. Starboard side does not alarm at all.

During normal operation, the oil pressure is good, about 40, temp is about 175, and there is no change in the way the boat handles or operates (including speed) while the alarm is sounding off. Good water flow from both sides from the exhaust. Oil coolers have been back-washed and port side had large chunks of impeller in it (no change after the oil coolers were cleaned). Transmission fluid is red and does not smell burnt (that I can detect). Engine oil is good.

2 of the 5 mechs suggested that it is the transmission, 2 think it's a faulty sensor...somewhere (reading the codes with their laptops produced nothing) and 1 wanted to replace the transmission just by looking at it..from the dock!

I have replaced the manifolds and risers...didn't help. I have had 2 techs on a Sea-trial with IR temp guns but the alarm did not sound.

Any idea of how many sensors would produce a solid tone? Is there a heat sensor on a Velvet drive 20-01-004? If so, how do I test it?

Any ideas on what could be alarming or suggestions on trouble-shooting are greatly appreciated?

 

[alldodge]

Re: Alarm on port side...baffling mechs

Welcome to the forum

I saw oil pressure on the port engine right about zero but other then that; Here is a list of solid one tone alarms
Constant tone alarms are for:
1.) engine coolant temp overheat,
2.) low engine oil pressure,
3.) engine overspeed,
4.) exhaust manifold cooling temp overheat
5.) sea pump PSI low.
Note #5 is known to be a common problem, It's been said that this fault might not show up in the fault history section of the scan tool.
If that is the case then the only other way to know if this is your problem, is to watch this sensor live as it happens out on the water with the scan tool hooked up to the engine.
Also make sure all the Battery cables are clean & tight plus a fully charged Battery is very important.
Check the water pressure sensor threads for any paint, Also check the sensor to see if it has come loose or Has a blockage of some kind.
If any sensor loses it's ground it could sound the alarm. As an additional test, try adding a ground wire to the sensor threads to stop the horn.