[wakeboardmaniac]

I am new to this site but am grateful that I found it. We have a 1995 Mariah Z190 with a 4.3L V-6 Alpha One Mercruiser engine. The boat actually belongs to my father in law and they let my wife and I use it for the summer. We also used it 4 summers ago and it didn't see water any time in between. The in laws are retired and on the road in a motorhome now. The boat is in excellent condition- it has always been garaged and covered. I don't think he has maintained it as well as he should have though. I changed the oil which was pretty dark and the lower unit drive oil which had a bit of sludge in the bottom of the reservoir. It didn't really look like water although I suppose it could have been. All the oil that drained out the bottom looked ok. I also had to change the water pump since it was leaking out the front gasket. Used a Merc. OEM replacement.

Took the boat to the lake and after 10 min. the warning alarm started going off. (The initial alarm came on and went away.) At first faintly then louder. Only when the boat was on would the alarm go off. I know that the alarm warns of low oil, low drive oil or hot temp, but all gauges and levels appeared ok. Got home, checked oil level again, changed L.U. Drive oil again (level was ok), and ran with muffs to be certain water pump was working. All appeared to be OK. Except the alarm went off as soon as I started the boat and gradually got louder. Everytime I started it up it went off faintly at first and gradually louder. The motor wasn't even warm yet. Could I have a faulty level or temp sensor? How do I diagnose this?

Also, I wonder if it could be related to the lights and the dash lights dimmer. 4 years ago if the dash lights were turned on the alarm would sound faintly. It could be silenced some by dimming the lights completely. Could the alarm noise be related to the lighting system?

Any help is greatly appreciated, Thank You!!

[WetWilly]

Hi wakeboardmaniac and welcome to the club!

First thing I suggest is for you to consider becoming a contributing member, this way, you'll have access to service literature to help you maintain your Sterndrive. Click here if your interested.

Now for your alarm, yes, it sure does sound like one of the senders is bad and my first guess is a faulty oil level sensor due to the sludge you mentioned, but we'll see.

Locate the alarm's oil pressure. water temp and oil reservoir senders (they will all have a Tan w/Blue stripe wire attached. Do not mistake this wire for a solid Tan wire, that's for the water temperature sender connected to the gauge on your dash.

This is the fast and dirty way to isolate which sender it is;

Start the motor and when the alarm turns back on, disconnect the Tan/Blue wire from the oil level sender first then the water temp sender. If the alarm goes off, it was the last one you disconnected and if the alarm is still going with both of these disconnected, remove the Tan/Blue wire from the oil pressure sender and the alarm better go off.

Originally Posted by wakeboardmaniac

Also, I wonder if it could be related to the lights and the dash lights dimmer. 4 years ago if the dash lights were turned on the alarm would sound faintly. It could be silenced some by dimming the lights completely. Could the alarm noise be related to the lighting system?

I hope not, the alarm circuit is really very simple. Power comes from the ignition switch to the alarm buzzer via a purple wire, then out of the buzzer is the Tan/Blue wire that goes back to the three senders. The senders provide the ground for the alarm buzzer.

Good luck,
WetWilly

[ShabahZ280]

If your senders aren't working properly, make sure and replace them. My alarm never worked when I got it, so I started looking into it myself. Found the previous owner had disconnected the piezo. I reconnected it, and it was acting strange and beeping every 2 seconds. After many visits to the service center, found out the drive oil level sensor in the reservoir went bad. This could very well be your problem, especially since you found sludge in there!