High Water temp Alarm and High temp related questions - Mercruiser 3.0 - Year 2003

[BayMisha]

Dear experts,

I am brand new in boating and just bought second hand Bayliner Capri 2003 year with 3.0 MerCruiser 135HP (I guess it's LX version). Motor is year 2003 and it has Alpha One 2 Gen Sterndrive on it.

During my first run (I had to drive boat from 80 miles away location to home dock through the sea) alternator belt broke.
When that happened I heard something but I thought fishing rod smacked about something. I noticed that Voltage gauge dropped voltage and after a while steering wheel became hard to turn...

Since that noise, when belt broke, and after I stopped the engine, passed 5 to 10 maybe 15 minutes. During that time boat was planing - around 3.200 to 3.800 maybe 4.000 RPM

The problem was also with Temperature gauge which wasn't working... Through all time when I went test the boat and driving it home needle was showing around 130F which I thought was perfect temperature. After that event I started to suspect something was wrong with gauge or temp sender. Last Saturday I replaced temp gauge with new one and now it shows constant temp around 175F

Now to my questions:
1. Bayliner has built-in alarm in case Temperature raises too high, Oil pressure drops... Is this alarm connected through gauge (I mean when gauge shows too high temperature gauge switch lines together which switch on alarm) or Alarm starts when temperature sender sends enough low resistance?

2. What should be the temperature when Alarm starts?


I spoke with mechanic and he told me that there should be enough water cooling made by impeller since there was no smoke out of the engine or smell.

How can I examine if everything is OK with engine after that event? Should I measure compression? What is the perfect compression value for 3.0 MerCruiser?
(I read several forums and what I could find were only test results).


I appreciate your help. If any other information needed please just ask.


Kind regards,
Misha

 

[Bt Doctur]

1 the alarm circuit is a seperate circuit, has nothing to do with the gauge reading
2 guessing 212-220 F

 

[alldodge]

Manual states 100 psi minimum, but you should be closer to 150 psi for compression

 

[BayMisha]

Bt Doctur and AllDodge

thank you for your response and information.

Maybe for someone, who will have the same question as I had... I spoke with MerCruiser expert and he told me following:
Not all Mercruiser 3.0 LX 2003 have motor temperature connected to alarm, for that you need optional Temperature Switch, which is then connected with other Brown wire.

Water temperature using Faria Kronos Gauges showing 175F is OK.

Because of new impeller there wasn't any damage to the engine, maybe it was just running a bit hotter than normal.

Optimum compression would be form 130-150 psi however differences between cylinders shouldn't be more than 15%


Best regards,
Misha

 

[alldodge]

Agree the alarm needs to be connected to the temp switch and I have not found where one was not installed from the factory. Have found where it was disconnected, and or changed

The water temp switch used in the alarm circuit is connected using a Tan/Blue strip colored wire
The water temp gauge sender is connected using a Tan colored wire

 

[BayMisha]

Oh, now I see.. I was constantly looking at Bayliner Elecrical Scheme, where it shows how alarm should be wired. That's why my question if alarm is connected to the gauge...

BR, Misha