Nitro 190 TF Constant Alarm

[Kevin Harter]

Recently bought my first boat, a 1994 Nitro TF190 with Mercury 150 XRi. Took it out for a couple of hours with previous owner and everything worked perfect. Then a week later my son and I took it out and were out about 3-4 hours most trolling and bass fishing but on the way back in (no wake) a constant alarm sounded. Immediately shut it down and checked all gauges, oil, etc. waited a few started right back up but constant alarm still on. So we used the trolling motor to get it back to the ramp and loaded. Called previous owner and he stated only happened once before, years ago when he was low on oil. I checked oil it was good in both tanks, checked wiring everything seems good. I started it yesterday day at the house with garden hose/ear muffs and as soon as engine starts he alarm sounds, so I don't think it is an overheating problem. Alarm doesn't shut off until key is off. My son and I race 2-cycle go karts and I have some experience with building and maintaining air cooled 2-cycles but no water cooled "Marine" experience. Like I said I am new to this boating stuff. Is there anything else I can check before I drive it over to the boat mechanic. Thanks in advance!

 

[Scott Hammer TOXIC]

Do you have a Water Pressure Gauge? If so, what was the WP when you first heard the alarm?

 

[Kevin Harter]

Scott, Yes, I do but honestly I didn't even look at it. I was too worried about how I was going to get back.....

 

[Scott Hammer TOXIC]

That will tell you if you are overheating or not getting WP from a bad impeller, stuck thermostat, etc. The only other way is to take it to the dealer and let them read the code(s).

 

[Boat4life]

Kevin, constant alarm normally indicates overheat problem. But in your case with the engine cool and being cranked on garden hose/ear muffs, it shouldn't have immediately alarmed. It would normally take a few minutes before getting hot. Several possibilities.....

1-water pump impeller bad
2-thermostat bad
3-alarm bad

Other notes:
Normally the thermostat stays closed until engine reaches a certain temp and then opens.
A bad impeller could be brittle and pieces broke off and have restricted the cooling passage.
Alarm buzzer could be stuck sending a false alarm.....a new replacement would solve it.

The key is to assume the alarm is real until you prove otherwise. I'm sure there are some other ideas out there.

 

[Kevin Harter]

Thanks for all the help guys. Well, I ended up taking it to a local Marine Service center this past Friday. Originally after having my boat a few days I was told that it was a module for the oil system that was bad and it needed replaced ($117). Should be done on Thursday. Well, they called back Thursday morning and said they had changed the module but the alarm was still there. They did some more testing and now are telling me they think it is a nylon gear that is on the crankshaft that turns the oil pump that may be stripped or missing a tooth and gave me 3 repair options. Option #1 tear down motor completely and replace gear on crankshaft $1,400 for parts and labor, Option #2 put an aftermarket electric oil injection system on the motor utilizing original oil tanks $935 parts and labor, and option #3 drain fuel, plug oil tanks and pre-mix fuel/oil 50:1 in the future........ I have already changed my perspective about owning a boat!

 

[AirForce]

sounds like another one of those mechanics that are not certified by Mercury or has the proper diagnotics tools and tend to throw parts at it. I'd want a certified Mercury tech look at it.

 

[fatrap]

Certified Merc technician for sure. I don't know what you paid but when You buy a used boat be prepared for something like this. Some times there's a reason the owner is getting rid of it. Granted you test drove it with the owner but the fact remains be prepared to pay for a little extra. Boat means " break out another thousand". Have a merc technician give it the once over and get all the things fixed then you won't have to worry about it. There's a ton of those engines out there and the run great. Don't let this get you down on owning a boat.
fatrap

 

[cq]

+1 for certified technician.

cq

 

[Dan J.]

We've found numerous times that the oil intake pickup screen on the saddle tank can have an algae growth develop over years and restrict, if not plug, the pickup line and setting off the sensor. If you look through the Search engine here you'll find a number of instances where this was the culprit. I hope it is in your case as it is a very easy fix and you'll be back in the water in no time. If they haven't cleaned the screen and blew out/replaced the line it is very much worth a try at the most minimal of costs compared to the options presented. Good luck!