Need help with new boat issue

[Todd Yost]

I just picked up a new to me boat, 04 24v, with the 375hp motor(w/ closed cooling). The issue I am having is the boat is overheating. I took it out for the first time and we drove it out of the marina everything was final got it up to 2500 rpm's and regular temp then all of a sudden it spiked. So I slowed down and it was still spiked. I shut her off for 10 min or so and went to see if it somehow fixed itself....didn't happen. i thought must have been impeller(no prob),we got back to the marina loaded it up and off to the shop. My shop guy told me the impeller had an imperfection in it so he swapped it out. Then tested it and realized the boat was super low on antifreeze. So he filled that up and still having the same problem. He told me the lake water is getting to the heat exchanger, so the intake is staying cool but the outflow is super hot. I just thought I would post here and see if anyone has had similar issues and what they did. Thanks!

[GUY_RPM]

Sounds like thermostat sticking to me.

[WakerideN]

this may sound ultra stupid. But make sure your hoses are setup right. last year a friend of mine had taken a boat to the dealer and they swapped the intake and out hoses. and it sounds very similiar to this. but it was not closed cooling.

[Stingreye]

Maybe a blockage in the heat exchanger that is making water flow poor through the exchanger, try backflushing it? The low coolant is likely due to the engine getting hot. When I lost my serpentine belt, my temps got to 200 and I lost coolant. Also, if the previous owner blew up an impeller, I think pieces could end up in the exchanger.

A link I bookmarked:
http://www.boatinghowto.com/download...t_too_cold.pdf

Heat Exchanger
Most heat exchanger problems are caused by debris causing a blockage or the
heat exchanger getting dirty as it ages. Depending on the amount and size of the
debris, it may be possible to remove it by back flushing the heat exchanger.
Remove the hoses from the heat exchanger and flush water through it in a
direction opposite its normal in/out flow. Some exchangers have an end cover
that is removable to make cleaning and debris removal easier. To take care of
dirt and scale buildup the heat exchanger should be removed from the engine.
Any of the more reputable radiator cleaning solutions may be used to clean the
heat exchanger. A small diameter brush with a flexible handle may be needed to
clean some of the passages. If the buildup is excessive the heat exchanger may
be taken to a radiator shop for cleaning. Make sure the shop has experience with
marine heat exchangers. Professional cleaning is normally a two step process
using an alkaline solution to remove dirt and then an acidic solution to remove
scale buildup.

[Stingreye]

Also, congratulations on the new boat! I love my 24V. "Long live the V!"

[TeamAllen]

Was the impeller in pieces or intact when the shop mechanic removed it?

[Todd Yost]

So I talked to the mechanic yesterday. He is has trouble getting flow out of the impeller pump to the rest of the system at idle. At this point he is just trying things, he has been on the phone w/ PCM a trying to get things figured, there is a super long run to the impeller pump that is making him think it is difficult to get water to the pump. He baskflushed the whole system and was still having issues. I told him to replace the pump to see if that will do the trick. Fingers crossed....

[Stingreye]

It sounds like you have the Pcm zr6 motor. There is a manual on planet Nautique in the downloads section for that motor it has the water flow diagram (motor was more common on nautiques than tige at that time) . From memory, mine goes from bottom of the boat, to the v drive then Trans cooler then the pump/impeller then exchanger then out the exhaust. I think that's pretty common on any v drive. The only time I have had trouble on mine, I messed up the gasket on the pump as I put in the impeller. It caused to to suck air. It also left marks on the impeller from running dry (sign of no water getting to impeller) . New impeller and gasket fixed the problem. So if you impeller isn't sealing, I bet the new pump will fix it. Good luck!

Sent from my SM-N900T using Tapatalk

[bigtige72]

That's a weird one... My 2004 24V is in for a high idle problem... 1200 rpm... Which they found the alternator shot..??? Well. Not sure how that can cause a high idle.. But I'm paying for it

[IDBoating]

mine goes from bottom of the boat, to the v drive then Trans cooler then the pump/impeller...

Standard routing on v-drives. Not unusually "long" at all.