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My Monterey
Heinrich

Genset Kohler 5E Overheating

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Hi all,

 

With limited space on my 2007 Monterey CR 270, doing some digging around the genset to do some analysis myself was no small feat (I bet midgets could make a bundle doing this kind of stuff...). Needless to say having someone work on it... apparently means taking the whole thing out... (and it will likely cost an arm and a leg and probably a kidney). The Genset was clearly not installed to be worked on later...

 

I was hoping to get some advice (before giving up a kidney). My genset is clearly over heating (extremely hot to the touch) and cutting out after a few minutes of running perfectly (or at least the way it should sound). So, that's probably a good thing... before it goes up in smoke.

 

So here's what I have been able to check so far:

- I have checked the impeller and its perfect (even checked that it pumps water out by the outlet (just to the left of the impeller by the outlet). Also, there is the little upside 'U' (I think it’s called a siphon break... well, if you open it... water comes out... (and yes, it is way above the water line... so clearly it comes from the pressure of the impeller pumping water thru the lines - somehow). Hard to follow the water pipes (due to limited space and visibility).

 

- Also, I have taken out the mechanical high water temperature switch (I put into a pot, cooked it and when it reached +- 180F it seems to open about 1/4 inch - I assume this is when the engine reaches its normal operating temperature to allow the water to bypass and help with the cooling). So, this seems okay or is it?

 

I was told to take the mechanical switch out and try it all out and see if it makes a difference... well, before I undo all the bolts... I want to hear from fellow boaters that may have solved this problem in the past.

 

- Lastly, I spent $100 essentially having an 'expert' tell me it’s not the coolant fluid (yep, getting to that little holding tank is impossible on this boat's configuration) anyway, at least now I know that you can open the cap on top and stick your finger in and get the same results (without seeing the holding tank on the back).

 

I assume the temp sensor (also attached) is working since it is cutting out the engine.

 

Also, I am pretty sure that no line contains any broken pieces of impeller (however, at this point I am open to any suggestions). Any suggestion to validate that water is running thru the 'main reservoir' to cool it off?

 

Needless to say my preference is not to open the whole thing again, just to try it out without the temperature switch.

 

Any other ideas would absolutely be welcomed!

Kind regards,

Heinrich

 

 

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Have you tried to remove the little plug on top of the heat exchanger and pour antifreeze in through there. It could take up to a cup or two. I had a similar problem and it turned out to be an air lock in the heat exchanger. Somewhere on the top of the exchanger is a quarter inch plug take that out pour antifreeze in until it is full. The other thing I did was flush out the raw water side of the heat exchanger with the dock side water. I disconnected the hose after the impeller and took the farthest away hose I could on the exit side of the heat exchanger and ran fresh water through it. There was the smallest piece of rubber that came out and the gen never over heated again.

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Does your generator have a heat exchanger, or is it cooled directly by lake water? Do you have the owners manual for it? This should help determine which one you have, and help diagnose the problem.

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The heat exchanger tubes have to plugged or restricted. If you're pumping water and what you see may not be the full amount that you should see.

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Folks, quick update (sorry for the delay!)... I had to winterize the boat (yes, it was a sad day)... So, I will only be able to check in a few months. Here is what I have done as well: I have taken out the mechanical temperature switch, and it made no difference (still overheats). I do now know that if you place the switch in a boiling pot of water that it opens up. I am also starting to think it must be a blockage (likely broken impeller piece or something??? It must have been their from a while back, since the one that is in the genset has no broken pieces...)... I will try the suggestion of connecting the short shore water line and running that thru the lines (I have a good feeling about that suggestion). Thanks! Anyway, I will check again (and report back) as soon as I can take her out of storage (where she is snug as a bug at the moment). Again, thank you for all the responses/suggestions I received!

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So, with the first blink of sunshine today I went to investigate again (as everyone has pointed out, it must be a blocked water line)… so, I decided to take off all the lines and make sure it’s open….

The first pipe I took off (and after blowing thru it), a piece of rubber (likely from an old broken impeller came out). So, I believe I found the culprit. Whoohoo! In a few weeks we’ll put her in on the lake and I’ll be able to confirm.

 

Anyway, learnt a few things thru this… a) I’ll never become a boat mechanic and B) Don’t just check the outlet where the impeller is – check all the water lines that water is actually flowing out strongly. Yep, maybe I should have tried the easiest thing first…

 

Folks, again thank you! It’s folks like you that make this a forum with not just a bunch of information, but knowledge!

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Looks like you might have solved the problem. :) I would still pull off the rest of the hoses, and flush them out too. There still could be more pieces of that old impeller somewhere.

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Congrats! Glad you found and repaired your problem. You just saved yourself some boat bucks to be used on something else for your hole in the water!

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Yes, as soon as I thought it’s all solved the genset overheated again after running a few minutes. Well, I decided that before I go talk to it with a hammer let’s give it one more try… So, this time I took the advice of folks on the forum and removed all the hoses and double (no, make that triple) checked that each was clean. Still the same issue occurred after I put it all back again (something like 2 hours later)…

 

I then spent a good few days googling and reading almost every conceivable site that had anything to say about gensets… and on some site a person mentioned air bubble… So, I though ummm… now here’s a new idea…

 

Anyway, turns out that the antifreeze (50% ethylene glycol) chambers (sorry no idea what that is technically referred to…) had an air bubble in it. To get rid of the air bubble, you need to remove a little screw (located on the top, opposite side of the coolant cap (see the image). This will bleed any air out of it (btw, you need to remove the coolant cap and fill it up while doing this). Lastly, turns out the manual also mentions this process, but does not say anything about this little screw that needs to be removed.

 

So, at least now I know that a) the lake water cools off the anti-freeze, and B) the antifreeze then cools off the engine…

 

Btw, that genset now purrs happily until it is turned off by me…

 

Fixed 1 problem… waiting for the next 1 to pop up… tick tock, tick tock…

 

Hopefully this is the end of my genset saga…

 

Happy boating folks!

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Folks, I came across an interesting boat forum page that has some great ideas about solving this issue (it especially mentions squeezing hoses to get the trapped air out). Apparently it is a known problem on this specific Kohler model. Would be great to know exactly which hose to squeeze (or some pic/diagram would be useful)...

 

http://my.boatus.com/forum/forum_posts.asp?TID=65798

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I'm having same problem, checked spark, oil, antifreeze, what should temp on radiator cap  and heat exchanger run, shut off with temp of 253 on radiator cap and heat  from exchanger 170

I haven't done the bleed valve on radiator cap yet to see if maybe a  air bubble

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