Need help troubleshooting Alarm on 8.1L Horizon engines

[mhanch]

Hey Folks,

I've got a 2000 Carver Voyager 374, and it has twin Gas 8.1 Liter Mercruiser Horizon engines (they are a repower from 2007). The boat is new to me, and what's happening is that the engines run great, but after about an hour of running around 1000 rpm (navigating a long no wake zone) i get a solid alarm buzzer from the Port engine.

- the oil pressure is normal
- the temperature is normal

I thought it might be the impeller, so i had that swapped out. that wasn't it. Once the alarm starts, i can't run the engine untiol the next day or it keeps going off. Next, I had a Mercruiser mechanic come out and check the engine for any stored codes. there was nothing, and he couldn't reproduce the issue.

I have a vessel view on order to attempt to gather more data, but I was wondering if anyone here had any ideas of what to look for?

Thanks for any help.

[tomschauer]

Check your transmission fluid. High trans temp will also give you an alarm

[mhanch]

Should I completely change the trans fluid? or just make sure it's up to level.

Edit: Looking over other posts, advice seems to be to just change out the Oil if in doubt. Pump it all out, refill. then drive a bit and repeat. after that it should be good. and Dexron III for the velvet drives. I'll give that a shot on both engines.

[Viper]

If the tranny fluid is in good condition and still a good colour, you shouldn't have to repeat. Empty and refill once is fine. If yours have filters, clean them first.

The alarm could be a number of things. When the alarm sounds, have you tried increasing rpm and if so, what happens? Does it allow the engine to increase rpm or does it go into Guardian mode and limit your rpm?

If they can't duplicate the alarm, it's difficult to tell what the cause is. Of course it won't happen when the tech's on board. It would be nice if they had hooked up Merc's recorder and sent you on your way for the weekend with it. When the alarm or problem occurs, you push a button and it starts recording engine data for a while. It then gets hooked up to a computer so the tech can see the data and determine the fault.

Are you sure it's an engine alarm and not a fume detector alarm?

[mhanch]

I don't think it's a fume alarm - thats a different place on the dash and it looks like it has an indicator light. Also when I shut that engine down the alarm stops. I will need to test next time, but I think I was still able to rev the engine when it went off.

Yes, getting the Vessel View will be helpful so I can capture data while we are out. It's a pain not to know what's going on.

[tomschauer]

Before you go out and buy a vessel view set up make certain your engines are compatible. The 2000's probably are not compatible.

[pepmyster]

Had a similar problem with my VP 8.1. Would shut down for no reason. Please check my posts. All could be the FireBoy module under your dash. If you have it. Mine would shut off my Starboard engine at random.

[Viper]

If you don't need the extra screen, look into the VesselView Mobile. You get all the info on your phone, has some pretty cool features, and is probably less expensive. A lot of businesses are going this route so they can monitor and check data on their fleets remotely. Check this out, pay special attention to the fault code display feature;
https://www.youtube.com/watch?v=pc4IiTsmsl4

[mhanch]

Y

Source of the post Before you go out and buy a vessel view set up make certain your engines are compatible. The 2000's probably are not compatible.

Yes, my engines are 2007 repowers. so they should be compatible. Mercury noted anything above 2004 with Smartlink, which is on my documentation.

[mhanch]

Update: I changed out the Transmission Oil in both Velvet Drives yesterday. It came out almost black, So I pumped it all our, FIlled with fluid, then Re-pumped fluid from the bottom until it came out pink. We went out for 2 hours (1.5 hours drive time total) and no alarm so far.

I'll take a longer drive when I get the Vessel View, but this was a good sign. Thanks for the advice!

Now I just need to fix/replace a leaking water heater....