2019 Nautique 200 6.0 Overheating Issue - and my wife thinks it funny...

jerrymjerrym Posts: 95 Baller
We have a 2019 Nautique 200 with the 6.0 liter engine and are getting engine cooling temp codes DTC 116, 1415 and 1416.

My wide thinks it humorous that we can't fix this problem considering the hours we have spent on it so far:

We have replaced the impeller and pump, reverse flushed the strainer, trans cooler and oil cooler, and tested and replaced the thermostat. The engine temp runs up to 200+ during a pass but cools at the end of the lake, so we know the thermostat is opening. The boat runs cold when no thermostat is in place but will not produce adequate power in this mode. The engine maintains temp when running city water into the inlet (essentially forcing more water through the engine).

Has anyone seen a similar problem?



  • scokescoke Posts: 749 Crazy Baller
    We have the same exact boat but never faced the problem.

    Question, did you ever swap out the thermostat BEFORE the problem as you mentioned
    "the boat runs cold when no thermostat is in place but will not produce adequate power in this mode"? If so, why mess with the thermostat?

    What's your normal water temp?
  • MarkTimmMarkTimm Posts: 147 Baller
    I had the same problem with my Ilmor 6.0, it was the pressure relief at the back of the motor. Not sure if the PCM is the same but worth a look.
    Mark Timm
  • ZmanZman Posts: 1,881 Mega Baller
    As @McGruder noted, look for any source of air being sucked in when under load. Check all hose connections from the hull fitting to your raw water pump inlet. Also, check that the strainer body is screwed tight against the gasket. Sometimes the screen isn't seated well up in the head of the strainer and keeps the can from sealing against the gasket.
    You would be surprised how little air intrusion it takes to cut the water flow a lot
  • MattPMattP Posts: 6,311 Mega Baller
    We had this issue on a 6.0 this year. Had to bleed air from the tank at the rear of the motor to get the coolant to run in. It’s a split cooled water coolant system?
  • jpwhitjpwhit Posts: 133 Baller
    I've worked on and fixed cooling problems with very similar symptoms and as others have already mentioned, air leaks in the vacuum side of the raw water loop will cause these kinds of issues. And finding these kind of air leaks can be challenging at times. They can be in places you really may not expect.

    One key sign that's always true with these air leaks is that they'll happen on the lake but not when the boat is connected to a hose. That's because the pressure from the hose turns what is normally a negative pressure on the suction side of the raw what pump to a positive pressure.

    A surefire way to determine if you have this problem, is to buy a 6" piece of clear rigid plastic tube that's the right diameter to fit inside the output hose of the raw water pump. You also need a small length of extra rubber hose the same size as the output side of the raw water pump. Disconnect the hose from the output of the raw water pump and insert the section of clear plastic tube into that hose and clamp it. Then take the piece of extra hose and connect it to the other side of the clear tube and to the output of the raw water pump and clamp both of those connections. Basically, you're putting an observation window into the output hose of the raw water pump. Now go run the boat in a lake, not on a water house. And run it under the conditions where you have the high temps. If the water you see in the clear tube is nice solid clear water with no air mixed in, then you don't have an air leak anywhere on the suction side of the raw pump. If you do have a leak, then you'll see bubbles or large amounts of air in the clear sections of hose.

    If you do have air, then it's just a matter of tracking down where it's entering. One trick is to pour water over every part of the suction section of the raw water loop and watch for the air / bubble to lessen in the clear tube. Another approach is to keep moving the clear tube further and further down the suction side of the raw water piping. But that often involves different diameter pieces of tube and hoses. The final approach is to just take everything apart on the suction side of raw water loop and just closely inspect everything. But it can be very hard to see hairline cracks in some parts.

  • jerrymjerrym Posts: 95 Baller
    Thanks for the responses - much appreciated!

    @scoke - we swapped thermostats thinking that perhaps some debris had gotten into the thermostat and damaged it. We've seen this happen in the past when the impeller wasn't properly changed out.

    @MarkTimm - we'll check to see if we have a pressure relief.

    @MattP - we have a freshwater system so no coolant. You have me wondering if we have an air pocket in the system??

    Others - To check the inlet side of the pump, we bypassed it with a single hose over the transom into the lake and got good suction on the pump but the same overheating issue. This does not preclude a leak on the inlet if the issue is an air pocket in the system.

    We'll proceed to run down any air bleeds or air pockets, and the source of air.....

    thank you!!
  • buechsrbuechsr Posts: 149 Baller
    Must be frustrating.

    If its a 2019, is your dealer involved or at least aware in case you pop the engine?
  • JustinJustin Posts: 80 Baller
    @jerrym Does your boat have a fresh water filter/strainer? Seems silly but if its missing the rubber ''O'' ring it will suck air under throttle, could be as simple as that.
  • jerrymjerrym Posts: 95 Baller
    We pulled the hose from the raw water pump outlet at the thermostat housing and measured 30 gpm. Open to atmosphere. We then pulled the outlet hose from the circulating pump and measured 30 gpm there as well. Seems like this should be plenty of flow so we are moving downstream.

    Apparently there can be calcium buildup in the exhaust manifolds. We do not have hard water but we do use gypsum for water clarity. No sign of calcium buildup so far but I’m sure we pull in some silt since our lake level is pretty low.

    Still open for suggestions....
  • jpwhitjpwhit Posts: 133 Baller
    I'll repeat my earlier comment that I think an air leak on the suction side of the pump is still a potential. I didn't really understand your earlier response where you implied you had run a test that ruled that out. Not sure I completely understood what you did, but from what I could understand it was unclear if it would rule out that possibility. Putting a hose over the transom to feed the raw water pump will not rule this out if you just ran it at idle. There is only enough negative pressure on the system at higher engine RPM. And if you bypassed the trans cooler and ran that boat at load you'd overheat the transmission.

    Also what's unclear. In your earlier post is sounded like it only overheats under load. You said at the end of the course it cools back down. But then in your later reply is did sound like it was overheating at idle.
  • DWDW Posts: 2,403 Mega Baller
    @jerrym - at what pump speed did you measure 30 gpm? Typically, the raw water pump is relatively linear and close to 10 gpm / 1,000 RPM (Jabsco provides that data on their website). Agree with other posters, the probable causes are either the inlet water to the pump is entrained with air reducing efficiency and/or an outlet blockage is restricting flow given you have cleared out any inlet restrictions.
    Have you shot the area next to the sensor with an infrared temp gun? The sensor could be defective or simply seeing an air bubble at that point providing an erroneous reading compared to what is actually happening.
  • paulpaul Posts: 54 Baller
    We had a minerals buildup in our exhaust manifolds that restricted flow that materialized as a problem priming the raw water pump the first time the boat was put in the water. Flushed the engine with a dilute mixture of muriatic acid (2%) and all was good. Boat ran cooler after. Our lake is quite alkaline with Waterspots if not wiped down with soft water
  • jjackkrashjjackkrash Posts: 1,015 Mega Baller
    Isn't there a 5-year warranty? Or did the boat transfer owners too many times?
  • jerrymjerrym Posts: 95 Baller
    Thanks for the comments. This is beyond frustrating.

    @jpwhit We ran a single piece of hose from the pump inlet over the transom into the lake and ran at idle. There was no change in the flow rate and good suction at the end of the hose.

    @DW The flow tests were run at 3000 rpm. The 10 gpm per 1000 rpm reference is reassuring. Thanks for that data point.

    The boat only throws codes after multiple passes at 34 mph. Temp gauge is hitting 200 when this happens. The engine will then cool down into the 180s at idle. Starting cold it will also get into the 180s just at idle.

    The sensors are measuring the engine temp correctly and correlate with an ir sensor as well as the touch test.

    We have removed the tstat and the boat runs at full power but in the 130-150 range. We plan to run for a few days and then install another new tstat. The intent is to get solid flow through the system and flush it out.

    In the meantime we will check the pH of the lake. Our water level is very low and could possibly be alkaline. We’re not excited about running acidic solution through the engine but.....

    Thanks again ballers!

  • DWDW Posts: 2,403 Mega Baller
    @jerrym - you might want to take a couple of t-stats and toss them in a pot of water on the stove and look to see at what temp they (the one in the boat and a reference one) open and how much the current one compared to a new or better yet known good one opens. The bulb temp should be imprinted on the stat as a check.
  • aupatkingaupatking Posts: 1,696 Mega Baller
    My transmission intercooler inlet got crimped one time and allowed air to be sucked in to the system. Was a pain to find but I stuck an open end wrench in it and spun it a few times to re-round the inlet. Put the hose back on and never had the problem again. May not be your problem, but worth a look
  • DragoDrago Posts: 1,673 Mega Baller
    Sorry, but why don't you just put in a cooler t-stat?
    SR SL Judge & Driver (“a driver who is super late on the wheel and is out of sync”)
  • jpwhitjpwhit Posts: 133 Baller
    I understand what you did now, and that won't rule out an air leak at any speed above idle. Air leaks almost always manifest into problems at higher engine RPMs. That's because even tiny amounts of air entering on the suction side turn into large bubble in the high negative pressure on the suction side of the pump at high RPM. Those large bubbles displace enough of the cooling water coming in to cause high temps.
  • jerrymjerrym Posts: 95 Baller
    @dw we have done the boil test and they all open at the same temp. We will repeat the test with a precision thermometer. The temp rating is not on the tstat. We can see by the engine temp that they open when installed.

    @Drago -two reasons. One we want to know the cause of the temp issue. Two -apparently the epa has regulated the operating temp for vehicles to maximize fuel burn so you can’t just grab a 160 deg tstat at the autozone any longer.

    @jpwhit the flow rate of 30 gpm at the outlet of both pumps suggests that both pumps are operating at design. We haven’t found an air leak or any indication of one. 30 gpm should be more than enough to cool a v8. Any thoughts on how to eliminate the incoming as an issue? Kinda feel like we’re chasing ghosts.

    We’ll check the lake pH this evening.
  • Jody_SealJody_Seal Posts: 3,469 Mega Baller
    edited September 15
    Few questions:
    do you have a heater in the boat?
    Do you have an infrared temp measuring device??
    I would be checking the housing and boss Temps with the raytec and see if they line up with the gauge readings or diacom..
    Did the engine have any prior heating issues such as a over heat , tor up impeller?
    If you changed the impeller did you use other than PCM branded parts?
    Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.

  • buechsrbuechsr Posts: 149 Baller
    jerry, lots of good advice but maybe a call to skidim is in order. They have plenty of 160 thermostats although I'm not clear if you've bench tested a new one.

    Has anyone ever made a diverter hose for the tranny cooler so as to not restrict fresh water flow to the raw water pump? Jerry, I assume your tranny cooler is not on the pressure side of the raw water pump, correct?
  • jpwhitjpwhit Posts: 133 Baller
    I described one approach, in an earlier post in this thread, as to a 100% definitive way to completely rule out an air leak. 30 gpm flow rate at the conditions you measured does not rule this out and suggests you're not considering what happens when even a small amount of air expands 10x under a vacuum. It displaces a high percentage of that 30 gpm with air. You measured 30 gpm without the high negative pressure on the suction side of the pump when the boat is running at speed with everything hooked up.

    Another approach is to close the sea valve and remove the raw water pump outlet hose and connect a vacuum pump and see if raw water pump through sea valve will hold a vacuum.

    I know this sound a tad extreme, but when you have a very elusive overheating issue its often that you're trying to find a somewhat rare and elusive cause. I work on a lot of boats and in two cases in the past with a cooling issue that folks couldn't figure out, this ended up being the cause. One was a hairline crack under the pipe clamp in one of the elbows for the strainer, the other was a hard to see crack in the transmission cooler.
  • jerrymjerrym Posts: 95 Baller
    @Jody_Seal we scanned the external temp with an ir sensor and confirmed the temp gauge. We had no prior temp issues. We check the impeller every 50 hrs and change it at 50 or 100. We have seen what impeller debris will do in a previous boat and learned that lesson. We use pcm parts.

    We have a heater. Why do you ask??

    @buechsr we just received a new tstat and find that it is a 160 deg unit. We have confirmed that all of the tstats will open around 162 via the boil test.

    @jpwhit sorry if I wasn’t clear but the 30 gpm is at 3000 rpm with the intake connected and the boat in the water. If it was sucking air, wouldn’t that displace water and adversely affect the flow rate? We see no sign of air bubbles in the output of either pump.

  • skihackerskihacker Posts: 456 Solid Baller
    So serious long shot but here goes, generally the reason an air leak on the suction side will cause overheating is because an air pocket behind the thermostat won't open it, how many hours are on this thing? Any chance it's popped a head gasket and is building a pocket of combustion gas in the coolant passage? With an open cooling system it will be hard to know for sure. Any misfire codes? Slight sputter at start up? Maybe pull all the plugs and see if one looks "washed"? Like i said a long shot but none of the usual stuff has fixed it.
  • SethroSethro Posts: 343 Crazy Baller
    I can’t imagine it happening in a new boat such as yours, but I once fought an overheating issue and eventually tracked it down to the insides of the exhaust hose had collapsed causing a major flow restriction.
  • DWDW Posts: 2,403 Mega Baller
    Water inlet grate clear of any obstructions?
  • mlangemlange Posts: 234 Baller
    I'm interested in Jody's comment on the heater. On the Indmars there's a separate circulation pump for the heater and if that goes bad it can cause an overheat, but I didn't think PCM used a circulation pump.
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