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Monsoon LT4 Cooling system info


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Gearguy911

Does anyone know how the LT4 cooling system works? There are two cooling reservoirs and one seems to keep draining on me. Trying to find coolant on the bottom of the engine compartment, but nothing really. Its a new boat.

Wondering what each cooling reservoir is for or if they are interconnected somehow.


Ryan

 

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The rear most cooling reservoir is for the charged air coolant, which is the for the supercharger intercooler.  The forward most reservoir is for the engine coolant.  They are independent systems and do not share coolant.

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19 hours ago, Gearguy911 said:

Does anyone know how the LT4 cooling system works? There are two cooling reservoirs and one seems to keep draining on me. Trying to find coolant on the bottom of the engine compartment, but nothing really. Its a new boat.

Wondering what each cooling reservoir is for or if they are interconnected somehow.


Ryan

 

 

How long have you had the boat? It may be burping air out of the system.

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Both of the LT4s that I have owned came from the factory with no coolant in the front resevoir. They do not burp them. I also doubt that they actually lake test the boats... for that same reason. Dealers also seem to rarely lake test boats these days.

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2 hours ago, Idamon said:

Both of the LT4s that I have owned came from the factory with no coolant in the front resevoir. They do not burp them. I also doubt that they actually lake test the boats... for that same reason. Dealers also seem to rarely lake test boats these days.

They are lake tested. Probably not ran long enough to get it all burped out.

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I haven't had much success with the air purging naturally from the cooling systems, especially for the CAC (charged air coolant).  I always have to use an AirLift coolant purge valve and compressed air to vacuum down the system and then draw in the coolant.

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Gearguy911

Only got 6 hours so far on break in.

thanks for all this info! Im gonna buy some more coolant and just keep running it through. Crazy they dont make sure the res is full...

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Recommend buying directly from dealer or be certain on the exact right one to use... they do not mix well.

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Gearguy911

Im pretty sure i have a coolant leak. I filled up tank, let it sit. Sure enough it goes down a bit, but look in bilge and a puddle of green all down on bottom of boat. Cant seem to see any hoses its dripping out of. Any thoughts? 
 

2021 A24 and its tight in there, hard to see around the engine to see where could be leaking.

 

 

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dealer recently mentioned the CAC was under recall.  defective.  Needs to be replaced and they are working on getting those in stock.  Not sure if that is related to your problem.

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Is it the engine coolant reservoir that is leaking?

I would check and tighten every hose clamp you can physically get to, then check them all again.  Pay close attention to the hoses on the port side that Go to the heater circulation pump.

I think some of the CAC pumps had an issue with a thermal shut off switch that would then cause a High Intake Air Temp alarm especially at higher RPM or under heavy load.  It is definitely not a recall (which is only issued by the USCG for very specific failures) and I haven't even seen a service bulletin for it yet, but I have seen a couple boats that needed it.

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34 minutes ago, Idamon said:

All I can add is to check your winterizing plugs for o-rings. Beyond that, make the dealer fix it quickly. Good luck.

Winterizing plugs should all hold in raw water, not coolant.  But it is a good idea to check everything anyway.

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Ok think i found it. It was one of the heater lines, the 90 line had a kink in it, and it had small leak from the straight connect. Straightened it out and it seems to have held overnight.

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