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409 temperature fluctuation


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Thanks in advance,

I have a 2014 A24 with the 409. I put the boat in the water a couple weeks ago and traveling to the dock it had a warning and the gauge said the temperature was over 200. I immediately turned off the boat and waited a few minutes. Once I started it again, no issue whatsoever. Since then I've been keeping a very close eye on the temperature and it seems to fluctuate between 160 on the low end and the mid to upper 170s on the top. I have seen it into the 180's, but that was maybe twice.

The other day we were out and after idling for about 15 minutes at the dock, we slowly moved across the lake and the temperature spiked to 200. There was no alarm or anything, and because I've noticed the temperature goes down when the boat is moving fast I gave it a little gas(I know, but there was no alarm) and the temperature immediately came down.

What's odd is the temperature seems good once everything has warmed up, and it's usually coolest(160's) when under load(tubing or surfing). I have noticed that the boat will slowly creep up in temperature when at idle and then it's almost as if the boat notices it's too warm and the temperature comes down very quickly.

Two questions;

1. I'm going to have the dealer look at it, but should I stop using the boat until then or just keep an eye on the temperature and be careful?

2. Is this normal? If not, what do you all think? Impeller, gauge, thermostat?

 

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I've got a 2012 23lsv with the same engine and it just started doing the same thing.  I swapped the impeller and still happening.

Would love to hear what your dealer says.

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formulaben

At this point I'd be pulling the impeller and inspecting/replacing, but before you remove it I'd look at the impeller cover/face plate and make sure it is tight.  A loose face plate or bad gasket could allow it to suck in air at low RPMs but at higher RPMs the higher vacuum pulls the cover flat and seals.  You can check it by spraying some soapy/foamy water around the cover on the intake side and see if it gets sucked into the pump.  If new impeller/gasket doesn't solve it, make sure trans cooler is clear of debris, all hose clams are tight, and then look to the thermostat.

 

From my cheat sheet:

  • Verify the raw intake valve is completely open; or if utilizing a flush or fresh water intake that the water input is routed from an open port/hose/valve as appropriate.
  • If on land, verify good water pressure to water intake (avoid using a fake-a-lake!)  Note that when using any type of external system it could mask a cooling issue.
  • If on water, bump the throttle to “prime” impeller in case of air in system.  If you have a “run dry” impeller (such as the Globe 100J) they are known to be prone to priming issues at times; if so, a short 1500-2000 rpm engine rev should prime it.
  • Verify the impeller (and gasket) is good; inspect/replace with new if ANY overheating.
  • Verify the transmission cooler screen (and raw water intake screen) is clean.
  • Verify the thermostat is good.  They are inexpensive, replace if in doubt.
  • Verify the temp sensor is good. They are inexpensive, replace if in doubt. 
  • Verify all hose clamps are tight and hoses are not kinked. Trace from the raw water intake through the entire system.  Check for loose hose clamps along the way and any kinking, especially around the tiller arm area upstream of impeller.  Any small openings can allow air to be sucked from impeller resulting in no prime, especially on impeller face plate.
  • Verify circulation pump is working.  If overheating at speed vs idle, it may be that pump.  Remove the drive belt and open the top port on the circulation pump and then turn the circulation pump by hand, with water in system you should see movement.  If a broken pump is suspected, remove entire housing and shake: if you hear noises, it is a broken circulation pump.
  • Like 2
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25 minutes ago, shawndoggy said:

Is this an indmar or pcm 409?

I think Indmar. I don't know much about this stuff. I know it's a Monsoon 409/L96 6.0Cat

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5 hours ago, formulaben said:

At this point I'd be pulling the impeller and inspecting/replacing, but before you remove it I'd look at the impeller cover/face plate and make sure it is tight.  A loose face plate or bad gasket could allow it to suck in air at low RPMs but at higher RPMs the higher vacuum pulls the cover flat and seals.  You can check it by spraying some soapy/foamy water around the cover on the intake side and see if it gets sucked into the pump.  If new impeller/gasket doesn't solve it, make sure trans cooler is clear of debris, all hose clams are tight, and then look to the thermostat.

 

From my cheat sheet:

  • Verify the raw intake valve is completely open; or if utilizing a flush or fresh water intake that the water input is routed from an open port/hose/valve as appropriate.
  • If on land, verify good water pressure to water intake (avoid using a fake-a-lake!)  Note that when using any type of external system it could mask a cooling issue.
  • If on water, bump the throttle to “prime” impeller in case of air in system.  If you have a “run dry” impeller (such as the Globe 100J) they are known to be prone to priming issues at times; if so, a short 1500-2000 rpm engine rev should prime it.
  • Verify the impeller (and gasket) is good; inspect/replace with new if ANY overheating.
  • Verify the transmission cooler screen (and raw water intake screen) is clean.
  • Verify the thermostat is good.  They are inexpensive, replace if in doubt.
  • Verify the temp sensor is good. They are inexpensive, replace if in doubt. 
  • Verify all hose clamps are tight and hoses are not kinked. Trace from the raw water intake through the entire system.  Check for loose hose clamps along the way and any kinking, especially around the tiller arm area upstream of impeller.  Any small openings can allow air to be sucked from impeller resulting in no prime, especially on impeller face plate.
  • Verify circulation pump is working.  If overheating at speed vs idle, it may be that pump.  Remove the drive belt and open the top port on the circulation pump and then turn the circulation pump by hand, with water in system you should see movement.  If a broken pump is suspected, remove entire housing and shake: if you hear noises, it is a broken circulation pump.

Thank you for your response. If only I was at all mechanical I could look into some of this. Your statement; "at this point I'd be …." is a clear sign it's beyond my understanding. I probably understand 15 percent of the rest of your statement. The motor has nearly 500 hours, and this will be my second season of ownership. I have a feeling this was happening last year and I didn't even notice. I think I'll just leave it to the dealer and not drive it until it's sorted out.

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The 409 is a bit weird in this respect. There is another thread on this but it is hard to search the forum on my phone. 

Does it only over heat when you have just started the boat? It’s seems to be a priming issue with the 409. If you take it to the dealer, unless the impeller is completely shot, they won’t be able to replicate it. Next time you are out. Give the throttle a decent start right when you move from starting/restarting (you don’t have to drop it, but give it a good rev). This method should fix your problem (if it isn’t a destroyed impeller). 

Edited by hunter77ah
Clarification
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2 minutes ago, hunter77ah said:

The 409 is a bit weird in this respect. There is another thread on this but it is hard to search the forum on my phone. 

Does it only over heat when you have just started the boat? It’s seems to be a priming issue with the 409. If you take it to the dealer, unless the impeller is completely shot, they won’t be able to replicate it. Next time you are out. Give the throttle a decent start right when you move from starting/restarting (you don’t have to drop it, but give it a good rev). This method should fix your problem (if it isn’t a destroyed impeller). 

Yes, this sounds exactly like the issue. I've looked all over for a thread that might talk about it. So basically when I start to put the boat in gear, just give it a good push to get things primed? Any idea what the title of that thread might be or what to search for?

 

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22 minutes ago, abovewater said:

Related; is it normal for the temperature to fluctuate between 160 and the mid 170's?

I wouldn't think so.  Both of these symptoms would be consistent with your raw water system sucking air somewhere.

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The Indmar 409 usually has a black rubber cooling system air purge hose that goes from a small metal tube on the the cylinder heads to a through hull fitting on the transom just above the port exhaust outlet.  If the hose, tube, or through hull fitting gets clogged, it is common for the engine to overheat at idle speed, but will not overheat during higher throttle use.  When running the boat on the trailer using a motor flush, you should see a stream of water water coming straight down out of the small transom through hull fitting.

  • Like 2
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Thanks everyone for the info. I just got off the phone with the dealer and they basically confirmed that the intake needs to be "primed" a bit. They said they often do this with boats in the shop. They also said it was normal for temperature to fluctuate and once it got a bit higher in temp the thermostat would kick in and bring it down. Normal for this motor to run between 160 and 180, which is also what it says in the engine manual.

Hopefully one less thing to worry about in this crazy world. I'll keep an eye on it moving forward.

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  • 2 weeks later...

Hello all....I have the same 2014 A24 with 409 and took her out on the first trip of the season last weekend only to be cut short with an over-heat alarm.  I also tried the "prime" but in idle the engine would always over heat...so into the shop she went.  Got her out yesterday and the mechanic stated the first thing he checked was the impeller (which was basically new).  He then moved to check the raw water intake screen just before the tranny cooler.  Seems like this design doesn't allow for a way to backflush or clean the intake without taking hoses off.  Mechanic stated this is common for this Indmar design, unlike the Nautiques where there is a screen that can be cleaned easily.

After cleaning the mechanic ran the engine for 30min+ on idle in his driveway on a hose and the engine stayed at a constant 150.

I'd definitely find a way to get your eyes on this raw water intake screen.

If I can figure out how to upload pictures I'll send along the before/after of the intake screen.

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  • 3 months later...

I just fixed my clients boat with this exact problem. Hasn't had the problem again. I tested the timing of water flow to every connection and tried to make it faster and smoother because my client kept having this problem. If the below doesn't work and parts have been replaced, then the exhaust cooling pipe is too corroded for flow and will need need exhaust cooling pipe (this depends on your model of exhaust).

1. Ensure seal is good on impeller housing and the impeller doesn't have damage on the inside of the fins. Replace as necessary. Place Blue Loctite on threads. Noticed the screws come loose causing air leaks.

2. Check for signs of water leaks on thermostat housing. If the housing has a leak, then the thermostat will get corroded and work randomly. I removed the housing and placed water sealant paste on the threads of the hose connections that screw into the housing (if you have that model). There is a plug as well on a particular model. Remove that plug and place a new one. The one that it comes with obstructs water flow causing the water not to flow smoothly. (Place thread sealant on all screw in connections). I also placed Red RTV around the thermostat housing (for the models that require a gasket due to the O-ring being absent around the thermostat, you do not need to do this) to ensure the thermostat O-ring doesn't leak by. Place blue Loctite on screws that hold housing in.

3. Check heat exchanger for clogs, clear any obstructions. 

4. Check strainer. Strainers get cracks in them sometimes and causes leaks in the vacuum stage of driving the boat. You wont see a leak running water through it. Replace if any cracks in strainer. Also, try to place strainer sideways in the compartment if room allows. It removes the delay of water getting to the system. 

5. Lastly, check the transcooler connection. The inlet and outlet connection should be facing towards the back or front of engine (depends on how your facing, if you are looking towards the back of the boat, which you should be already in this position, the connections should be facing towards the back), not up (some models don't allow for room to make the inlet adjustment, it will be fine if the above steps are completed). The connections will allow you to place these in either direction. There was an update for this per manual that they don't tell anyone. And shorten the hose from the transcooler to the heat exchanger. And ensure the system is flushed because stuff likes to get stuck in the transcooler. If you have a certain model, ensure Zinc anodes are new and connections cleaned. They could break off and cause a clog. 

I also told my client to run fresh water through it before and after every use. This helps prime it and keeps it clean.

 

Edited by yzbusta
Grammar and additions.
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