Another..... Overheat thread!

[turret_plug]

2010 Mercruiser 3.0 (TKS) with power steering..... Bought used, went our first time, alarm sounded and temp spiked at about 195-200 F after about 2-3 hours of use (At around 3500 RPM). Let it cool off, went home.

Took it to marina, had impeller replaced, T-stat replaced.

Took out again next weekend, pretty much the same condition, back to marina.

A little history though, boat has MASSIVE stereo, and we noticed an audible squeal, but not the belt, it was from actual alternator (I figure it's dying). Mechanic called and stated alternator needs to be replaced, and that it is most likely causing the belt to slip because it is seizing, and not spinning the circulating pump very good leading to an overheat condition.

They are also flushing the PS cooler and pulling all hoses to ensure no impeller fodder is lodged in the cooling system.

Boat otherwise runs very well, but I just wanted some opinions here before I doo doo more money at this cooling issue.

Thanks!

 

[alldodge]

Howdy

Unless the ALT is stopping the circulation pump, I don't see it causing the overheat. I would start looking for a restriction somewhere or go back and relook at the drive water pump housing. Are you in salt or fresh water?

 

[turret_plug]

fresh water only.....

He makes sense in his argument, and the alternator does need to be replaced. They are also looking for any restrictions, blockages or whatnot in the cooling system.

It has great volume when running on the hose, healthy output on the lake. I'm sure it's something silly. He was also asking good questions, like "is it difficult to steer under load" pointing to a sticky PS pump, etc. I trust them, and they have a great reputation here.

Crossing fingers its just something dumb. He also told me IR temp showed about 175 all over motor. Told him to go ahead and replace temp sensor as well.

 

[Bondo]

I trust them, and they have a great reputation here.

Ayuh,...... Welcome Aboard,.... Yer Mechanic's theory is sound, 'n quite possibly 100% correct,....

 

[harleyman1975]

Turret plug...is that ARMY slang for tank commander? LOL!

 

[turret_plug]

@ Harleyman1975....... Yes, I am a tanker, That was the unfortunate nickname given to me as a loader many years ago.

Bondo, I just came back from the Marina...... It HAS to be that alternator. Mechanic showed it to me, its difficult to turn by hand (which accounts for the horrendous shrieking sound it made). The new alternator gets about 20 revs out of a simple spin with the hand.

He showed me the bucket of slop that was flushed out of my cooling system starting from the pick-up tube, all the way to the exhaust...... I think he nailed the issue. Better to pay him $500.00 to fix the problem, then to push it into a $4000.00 power pack.

I'll update the thread after this weekend if it's resolved for the DIY'ers on here. I used to be a DIY'er....... but apartment life has slowed me down!

 

[wahlejim]

Make sure the exhaust shutters are checked out. Those are one of the first to go in an overheat situation.

 

[alldodge]

First post

audible squeal,

Post 6

the horrendous shrieking sound it made

They just don't appear to mean the same thing

 

[turret_plug]

Shriek=squeal

Same thing...... semantics

He also pointed out my hydrofoil, stating that "sometimes" they can bring the rear out of the water enough that the intakes can't pull enough water in. He hates them, and told me to get rid of it...... said engineers are smarter than the people who invent and sell those to dummies like me! I'm going to pull that, I didn't really notice too much of a difference anyway.

I've never owned a foil before, first time I install one...... problems.

He talked to me about the flaps/shutters...... said all was well. Either way, I'll post the weekend results.

 

[alldodge]

Shriek=squeal

Same thing...... semantics

OK, your saying you went out twice and drove it until it overheated with a horrendous skriek/squeal going on all the time. Wow,

Good luck

 

[turret_plug]

OK, your saying you went out twice and drove it until it overheated with a horrendous skriek/squeal going on all the time. Wow,

Good luck

Anything constructive to add, or just sharp shooting me?

 

[FreeBeeTony]

How much current does this stereo draw?
Maybe that's what killed the alternator?
Maybe you need a bigger one.

 

[turret_plug]

How much current does this stereo draw?
Maybe that's what killed the alternator?
Maybe you need a bigger one.

That's a good darn question...... Thanks for that. I don't precisely know and when I upgraded the stereo from its original set-up, I knew I would eventually need a higher amperage ALT. I have 3 subwoofers installed, 3 1000W amplifiers, crossover and 6 tower speakers. I also have 2 batteries, starting and deep cycle (for stereo on the beach). Because of that, marina is installing a high amperage ALT specifically made for this type of application. He told me to experiment by NOT having the full stereo on underway, stating it may not put such a load on the motor, which I can recognize as solid advice.

The boat was never abused by the previous owner, and that's evident, but was neglected a bit by underuse. I'm betting they have it nailed this time. He showed me the IR gun temp today, below the T-stat housing, it was 173 at 3500-4000 rpm on the muffs, it displayed 175 on console gauge with that original "bad" alternator (which was hot as hell).

I'll get her out tomorrow and see how she responds to the cash backrub I just gave her!

 

[FreeBeeTony]

FYI......standard Mercruiser Alt are good for ~55amps.

 

[turret_plug]

Resolved....... in case anyone can use this to help themselves. Replacing the ALT solved the problem, along with the vigorous cooling system flush. There's no way that belt wasn't slipping on the circulation pump and causing an overheat condition. Add to the fact that I now have a super expensive (unfortunately) ALT in there rated at 90 amp, the stereo can kick some ath now too!

Temp gauge shows a healthy 172-175F temp. We kept it on the skeg for about 45-60 mins on plane yesterday around 35-4000 RPM. Never set the alarm off, looks like ilall the little problems just made one big problem.

Now we can have some fun again! Thanks for all the replies and help.