2011 Sport Nautique 200 V-drive PCM 343 overheating.

[House324]

Sport nautique running warm

I have a 2011 V-drive Sport Nautique 200, PCM 343 Raw water cooled, 422 hours.

Always runs 160 degrees till recently. Now it’s running 162-175+ when idling or fast. No real trend, one way or another.

Just a quick background to answer the obvious questions:

I’m a boat wrencher and have a very rigorous maintenance routine. I know the sea strainer gasket is the number one suspect, so I re-sealed and ultimately replaced the entire Sherwood strainer, cup and gasket. Sealed with silicone grease and I’m confident of the air tight seal.

I flushed out lines “in reverse” from thermostat housing to the intake.. Oil cooler is clear, new belt, 160 Oem thermostat, impellar, and hose clamps are tight. Sending unit appears to track well with temp changes.

-light coat of sealant added to each of the barbed fittings and re tightened all hoses.

-Impeller housing looks great, no grooves, and light silicone grease on sealing surface/o-ring. I replaced impeller just in case it spun on the brass spline from the increased vacuum with clogged strainer. Impeller double checked when installed with the "top" in the correct position.

-Checked serial numbers on engine and doesn’t seem to have a circulation pump recall/problem. (No leaking or whirring noise)

-Trans/V-drive in/out lines are clear.

-Never had an old impeller with a broken vein etc. I change impeller often.

-Thermostat seal seems good with an additional thin film of sealant, New OEM 160.

-Briefly ran the boat in the slip with different lines disconected to make sure flow looked good.

-Non contact thermometer on all areas to see if there was a temp difference between exhaust sides.

-Checked winterizing drain plugs, including oil cooler.

-Engine oil and trans fluid look great. Correct levels and no signs of water.

Yesterday my wife and I were idling along the lake while I watched the engine with the hatches off. I could hear a very subtle, “load/engine surging”. I could see my water lines (along the top of the engine - after the thermostat junction) surging and could tell that several slugs of air were flushing through the lines. After they cleared, the temp immediately settled to 160. But I couldn’t get them to reproduce the same thing.

The temps eventually went back to the same problem. I shut down for long time to see if gravity would suck in an air leak from above the water line, but could never get the same air surge.

“Kinda” good news cause I know its air related, but still can’t find the air leak.

Thanks for any input

[bturner]

Dang son, you hit everything I would have tried and then some. After everything you've done and considering the issue you had with heat and the age of the boat I would be looking for soft lines that could possibly be collapsing. These can be difficult to find at times. Just for reference my 2016 runs rock solid at about 172 all the time. Then again these gauges are not something I would trust to be truly accurate and consider them to be "in the ballpark" from an accuracy perspective.

Just thinking out loud... did 2011s have CATs? Is it possible that you melted down a CAT? Not sure, but I'd think you be throwing a code I certainly don't know for sure. Is there's a way to check them? Again, just thinking out loud and wonder if they have melted, would they act as a restriction getting water out of the system.

Maybe Jeff or Charles can chime in. They both seem to have some serious skills and experience and may have a better idea where to go next.

[House324]

Bturner,

Thanks for the reply. My 2011 has Cats. They didn't appear to get that hot. No discoloration, bubbled paint or burnt smell.

I've inspected my hoses as best as possible...Running and off. None appear to be collapsed from the outside. I've removed several and used a borescope on a couple around the thermostat to look for blockages. None of them seem to be problem so far.

Since I heard/saw the air surging, I'm confident its an air leak, but I just can't find it.

I haven't removed my entire impeller housing to inspect it, but I can look inside and there's no visible wear. Wear plates are smooth

I'm trying to figure out how make a pressure tester similar to a radiator tester. I'm planning to pressurize the intake hose near the sea stainer and plug off a hose after the pump I figure that a little bit of air pressure with a bike pump, soapy water and some quiet time, I might be able to find something.

I would guess that the air leak would likely be between raw water pump and the thru-hull intake. Downstream of the impeller pump, I would think the water pressure would turn into a water leak instead of an air leak anyway.

Thanks,
Jeff

[bturner]

Thinking out loud again. Have you checked your oil to see if you have any water in it? Could it be a blown head gasket? I wonder what the exhaust looks like when it's running out of the water? Steam perhaps?

Not trying to jinx you here, just trying to think about areas I've seen on both cars and boats that would let that kind of a leak in. I do like the pressure test idea.

Last thought would be the circulation pump on the engine but that one would be no fun to pull and to honest it's usually the bearing that goes on them. Ilmor had a bad run on these with on 2011 - 2012 5.7s in the MasterCrafts and there was a dealer tip on them. I believe they had veins that would break off. Not sure if the circulation pump is unique to Ilmor or if it's part of the GM supplied components.....

https://teamtalk.mastercraft.com//sh...t=48116&page=2

[Skidave]

1) Clog between hull scoop/pickup and strainer.

2) Obstruction in hose such as a small rock or seeds.

3) Seacock not open all the way (valve).

I sucked up a small rock one year. My pieces are as follows: hull scoop, seacock, Perko flush, strainer ...

I had a small rock stuck in my Perko flush. Since it is clear, I could see it in there. How it got through the hull scoop is beyond me.

My wife would love that giftcard if I'm the winner!

Dave

Sent from my SM-J337V using Tapatalk

[House324]

Still struggling with the temps being higher than normal. Nobody has a clue how much work I've put into figuring this out.

does anyone know where I can get a schematic of the cooling system for the PCM 343 (raw water cooled)? All I can find is the standard owner's manual.

[NautiqueJeff]

[SilentSeven]

Curious. I see you mention delta running...can I assume this is brackish water? How many hours do you think you have that sort of water? If brackish, is the boat flushed with fresh water post use? You mention surging engine water...have you considered possible corrosion damage to the main engine water pump? I've seen people run tests where a freshwater hose is connected the raw water intake and then run the boat...I wonder what your temps might be like if you ran that test.

Finally, any chance this might be electrical? ....I might do a look see on water temp sensor for corrosion / ground seating / lead conductivity. At the same time, do check of the engine block ground and battery ground. Seems like a long shot but that's where this problem is at the moment...?

[House324]

NautiqueJeff...Thank you very much. I know my boat pretty well, but just want schematic just to double check everything.


SilentSteven, Where I boat at the delta, it's all freshwater. No real signs corrosion in the boat and It's only been used in fresh water.

I've used a bore-scope snake and inspected a lot of the internals of the engine and cooling, no signs of problems.

The water temperature sending unit matches comparison to a non-contact thermometer.

[justdowitt]

i have been having the same issue, i think mine came down to a bad thermostat. Here is what i would check, when it is running correctly put your hand on the hose going into the main water pump, it should be fairly cool to the touch when the thermostat is open, when mine would hit 175+ that line was really hot, like the thermostat was closed. Rev it up and for whatever reason the tstat would open and cool everything back down. Took the thermostat out and found it was the wrong tstat(not a high flow one) and it also didn't have any bleed holes to allow air to escape when the thermostat was closed. A quick test ( but not a permanent solution) is to pull the tstat out and run without it, if you engine stays in the low 100's chances are the thermostat was the issue. Hope that helps

[House324]

When running the boat in the lake, I could feel air surging through the cooling lines. I replaced my top water line with clear tubing to confirm. You can see the air in the line when running. I don't see much change in air with different RPMs.

I've pressure tested my cooling system from the intake to the thermostat...no leaks. I do not know where the air would be coming in. Could it be a crack in exhaust manifold, manifold gasket or a head gasket?

Does anyone have tips of how I could diagnose the exhaust for a possible gasket leak?

Where else could the air be coming in?

[mpost]

From the cooling diagram that Jeff provided and your picture it looks to me like the clear hose is the first place the water is going to the engine. I count nine hose clamps, a water strainer o-ring, and the RWP seals and bearings, between the water pickup and hose showing the bubbles. this is all before entering the engine or exhaust manifolds.

[House324]

I have checked, tightened, sealed, bore scoped, many times. I pressure tested the cooling system from the thru-hull, transmisson, to the thermostat. It'll hold 30 psi of air for 20 minutes.

I don't fully understand the directions and routing of all of the cooling system yet, but that clear water line in the pic is a return to the thermostat from the catalytic converters.

[dskier]

Couple questions- do you have a Shower or heater? Possible loose connection or broken heater coil letting air in the return line? Last thing, I have a friend with a MC that a piece (very small piece) of his pretty good looking impeller Make its way down to a screen before it goes thru the exhulst that caused enough of a blockage to cause the temp to rise. Not sure nautique has this screen but I thought it was worth a mention.

otherwise good luck!

[mpost]

Guess the drawings are lacking in the completeness of your system. I don't see any of them showing Cats in the water flow. How does the water coming out of the cats get to them?