Can a bad stator cause a false over heat alarm?

[waterfoul]

As I posted before... I am at a total loss as to why my 1997 Merc 150 EFI keeps giving me an over temp alarm. Set up has not changed in several years (literally have changed nothing). We've changed every component of the water pressure system (except for the poppet valve, which we will be changing tomorrow). It's mounted on the transom of a 1997 Triton TR186 bass boat with a 6" jack plate set at 2" below the pad (pretty much a factory recommendation) and has been running very well for many seasons.

We're pretty sure that the stator is bad. The tach is all over the place and the starting battery is not being charged/maintained by the motor (I'm pretty much having to charge it after every trip out). This motor has no rectifier so that's been eliminated as a possible cause. I've ordered a stator and should have it in a week or so...

I'm just trying to get a better understanding of the system on this motor.

[RiceKiller]

How do you know the stator is bad?

And when you said you you changed every thing that means you put new thermostats and water pump and pump housing in and do you have a temp gauge on your boat and what is your water psi at WOT

[sschefer]

NO.. Not even related. You have a rectifier but you might not have a regulator.

[sschefer]

NO.. Not even related. You have a rectifier but you might not have a regulator.

[TEXAS20225]

its your regulator's that cause the tach to jump and also to charge or not to charge you may be running out of battery to maintain enough power to run your boat. stator is checked two ways one is ohms checked by checking between red/blue and red white / blue white wires for resistance it should be between 36 and 4200 with ohm meter set on RX 1000 it can be tested with DVA while running, rectifier changes ac to dc out of stator ITS A EFI not carb regs 2 are behind the coil plate on back of the motor RULE #1 buy a manual and a cheap ohm meter it will make your life as a boater easier to dig out more money:D:D:D:D:D ( 2'' below pad with a stock case seems high) maybe a torqmaster with the plates and only 4 low holes not 8

[johnnyracer]

Can a bad stator cause a false over heat alarm?

Not that I know of. But, a bad oil alarm box can.

[TXOBTECH]

Have you checked for water it the water/sep fuel filter on the engine? That will also give you a solid horn also.

[ess15]

I would be checking engine temp old fashioned way while running if possible, first to eliminate that it is not actually overheating with a mechanic down the back of the boat and one of the laser temp guns and the old hand test on the heads. If you have the two regulator recitifiers on the back pray that it's not them giving you the tacho probs because they are very expensive..

[TEXAS20225]

the gray wire thats on the regulators is what give the tach it signal. the regulators tell the system to charge the battery so its the reason you have to charge the battery every time you go out. new regulators ebay 48.00 each 1 year warranty?? i agree that you need to make sure you have a over heating problem before you try and fix it. what does your water pressure say 2-5 on idle 12/15 wot you do have a water pressure gauge right

[waterfoul]

Over heating issue solved! Mechanic (???) put the lower housing gasket in UPSIDED DOWN pretty much blocking off the water intake passage. Took a fresh set of eyes today to figure that out. 12 psi pressure at 40 mph and no alarms!!

Now on to the charging issues... which will have to wait a few days though...

[ChrisCarsonMarine]

The blue and red stator wires have nothing to do with the charging system,they power the switch boxes,for ignition.your trouble is most likely the regulators,and may be nothing more than poor connections on the bullet connectors between the stator wires and the regulator wires.If they are black and burnt,try cutting the wires and re-connecting with crimp connectors,insulate well,have the battery switch off or batteries disconnected,if that's not the trouble it's most likely the regulators,the charging system needs to be working properly,as an EFI is a constant loss system,Chris

[TEXAS20225]

Chris you are correct but dont you think its a good idea for these guys to get themselves a manual and a few testing tools so they can learn about their motor and not be crippled by every problem that comes along ? let him check it all he will be more confident in tackling a problem:)

[ChrisCarsonMarine]

True enough,Texas,a lot cheaper and satisfying than throwing parts at it.