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Overheating after de-winterization


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Hello all...this winter was my first one with and inboard and I am in the process of unwinterizing my 96 Sunsetter LX with Monsoon 320. I am running a garden hose into the intake hose just like I did during the winterization process (and had no issues)and it now reaches temps over 200 at idle. Between 180 and 200 the water will back up in intake hose spilling out the hose and the impellar starts to squeak...then around 200 it stops squeaking and the water sucks back through. There isnt much water coming out the exhaust pipes...I thought I remembered more when I ran it during winterization. I have followed all instructions from the Indmar/malibu manuals and am a little confused this is happening. Could this be a thermostat issue even though I didnt have any issues with it last summer? Please help...I hope its something simple...THANKS!!! :badmood:

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Have you checked the impeller? Is it lose on the hub the rubber slipping on the brass inner hub?

If you stored it over the winter with the impeller in it could have taken shape and not be any good.

Have you checked the Trans cooler for Debris?

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Bad impeller, Ball valve from the water intake not open all the way, not enuf water from spigot would also be things to check. Squeaking impeller worries me....

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I am running a garden hose into the intake hose just like I did during the winterization process (and had no issues)and it now reaches temps over 200 at idle. Between 180 and 200 the water will back up in intake hose spilling out the hose and the impellar starts to squeak...then around 200 it stops squeaking and the water sucks back through.

If water is spilling out around the garden hose, then the impeller should

be drawing an adequate volume of water. Since it's still running hot, though,

it may be that the impeller is bad, or that there is a leak, say, from a loose hose

clamp, before the impeller, or the gasket to the raw water pump cover plate is

inadequately sealed, allowing it to entrain air. Or, it could be that there is

some partial obstruction to outflow from the raw water pump, because of debris,

either in the hose from the raw water pump or stuck to the tranny cooler screen.

If you have checked out all of the above and all seems well, you may need to pull

the thermostat. Heat some water on the stove and measure the temperature. See

when that sucker actually opens.

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Do you hear the impeller squealing from the lack of water? I have 99 Sunsetter lxi and was having the same problem yesterday. It wasn’t overheating (yet) but I noticed there was no water was coming out of the exhaust. All I had to do was reposition the fake lake and water flow started. I think I had the fake lake pressed so hard against the water inlet was blocking the inlet.

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well the i stored it properly and removed the impellar for winter and replaced it with a brand new lubricated one with seal last week. I backflushed the cooling hoses..no issues...then removed all hoses and checked for any internal collapsing...nothing...then removed the thermostat and boiled it..opened at 160 degrees...checked cooler screen..nothing. I am not running a fake lake as the malibu manuals state those are not recommended and to simply removed lower hose from intake and run a garden hose into it. Like I said it is wierd...the water goes..no impellar squeak..water backs up..impellar squeaks..does this back and forth for a minute and then the temp will spike rapidly. I didnt have any issues like this before winter...maybe I should just drop it in the water and see if it still does it? I also broke oe of the 3 1/2 ich bolts in the thermostat housing when I removed stat...I tried to drill it out to retap it and I dont think it worked to well..need to find somewhere that carries that part for cheap.

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how possible is it for a new Johnson impellar to slip? The only mystery was that I got a rubber o-ring with kit and didnt see where to put it as it came with a housing gasket.

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When running the garden hose to the inlet side of the raw water pump you should not attach the hose to the inlet line with duct tape or anything. You want the inlet to "suck" the water, not force it into the engine. I use a large bowl or large bed pan and set it in the bottom of the engine compartment and put the inlet line and garden hose in there and turn on the water. Turn the hose on, and the bowl or bed pan fills up. I then start the motor and the inlet starts sucking. If you force the water into the engine you could get water in areas of the engine that it is not supposed to be...i.e. in the oil.

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That's a tough one to diagnose without being there. I'm not familiar with Indmars. If the thermostat housing isn't sealed because it only has one bolt, then there's your problem. Or if one bolt didn't tighten.

If it was a Mercruiser I'd say you had the coolant hoses on backwards. Other guess is wrong impeller.? I don't know anything about Indmar pumps. Was there instructions with the new impeller and gasket? Find out what the o-ring is for!!!

How about when the temp hits 200 you say it stops squeaking. How low does the temp gauge dip when it stops squeaking? Only 180? Sounds like a themostat prob.

Does it take a normal amount of time to reach normal temp ~150? Or does it overheat quickly?

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Put the boat in the water and try it. Where is the Thermostat though? Do you have to take off the engine plate on top to get to it? I think I need to look at my Thermostat and test it.

I may have a similar issue. My Monsoon 340 engine is running at 160 degrees at speed and 165 at idle like it has for the last 6 weeks, even though the lake temperature has increased from 68ish to 75ish in the last month to 6 weeks. I've checked the impeller, hoses, belt, trans cooler, intake, no leaks or debris and all seems clear. So, I'm moving on the Thermostat and then the exhaust manifold hoses for integrity and then the mechanic. I heard some Indmars had problems with the exhaust manifold hoses holding up, so maybe that's it.

I'd rather solve the problem now rather than wait for the water temp to reach 85-90.

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Put the boat in the water and try it. Where is the Thermostat though? Do you have to take off the engine plate on top to get to it? I think I need to look at my Thermostat and test it.

I may have a similar issue. My Monsoon 340 engine is running at 160 degrees at speed and 165 at idle like it has for the last 6 weeks, even though the lake temperature has increased from 68ish to 75ish in the last month to 6 weeks. I've checked the impeller, hoses, belt, trans cooler, intake, no leaks or debris and all seems clear. So, I'm moving on the Thermostat and then the exhaust manifold hoses for integrity and then the mechanic. I heard some Indmars had problems with the exhaust manifold hoses holding up, so maybe that's it.

I'd rather solve the problem now rather than wait for the water temp to reach 85-90.

Your Monsoon is operating as designed.

Lake water temp will not have any effect on your engine operating temp...that is what the thermostat is for.

Unless, of course, the lake water temp approaches 160 degrees..then the lake water may not be able to cool the engine properly.

Edited by rts
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rts, that's good news.

I had a Indmar 310 on a Sportster LX before this Monsoon 340 on my VLX and early in the spring and late in the fall, the engine would run 15 degrees cooler, around 145 degrees as the lake cooled. So you're saying that's not the case with the Monsoon? Why is that? I'm guessing the Indmar 310 didn't have a thermostat to regulate engine temp.

Thanks. I should've emailed you 6 weeks ago!! I could've spent my few hours of troubleshooting on the couch.

If the lake water temp is 160, I've got bigger problems...

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Here's the deal. When you start your engine, it should be at the air temp...say 85 degrees. Whether your sucking 50 degree or 90 degree water from the lake, your thermostat will be closed and all that water will 'bypass' the engine while it warms itself up. When the engine gets up to temperature, the thermostat should open, and the water that was previously being 'bypassed' will start to cool the engine, until the engine gets back down to about 160 degrees, then the thermostat will close again, engine temp rises...then the process repeats.

So theoretically it will take longer to cool back down enough to close the thermostat if you are in 90 degree water than 50 degree water (thermodynamics). But it really doesn't matter. Your engine (with your particular thermostat) will operate in a 'range', and it should stay in that range regardless of the lake temp.

A lower lake temp will mean that your thermostat will be open less, because you will cool to the low end of the range faster,but you should still stay in that 'range'.

Hope this helps...and at the temps you say you are running, you are in good shape...

And I would say you may have needed a new thermostat (I guessing yours may have been stuck open, or not closing all the way) in your old boat if colder water caused your engine to run 15 degrees cooler.

Edited by rts
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If you force the water into the engine you could get water in areas of the engine that it is not supposed to be...i.e. in the oil.

All the years of using Fake-a-lakes & hose adapters on the inlet & I've never heard or experienced that. Not saying it isn't possible. Just never seen or even heard/read of it happening.

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RTS-r u sure? The collant diagram I saw shows the water entering the block and circulates within the block, ... until the thermostat opens;.. then it allows new water to circulate. Maybe your coolant path is different than mine. Why don't you test it, disconnect your impeller and run it without water and see how much faster the temp climbs with no water. I think u'l find the water does enter the block, but isn't allowed to leave until the thermostat opens.

oh, and I disagree with areamike too. The water is under pressure in the block when circulating. It won't get in the oil.

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All the years of using Fake-a-lakes & hose adapters on the inlet & I've never heard or experienced that. Not saying it isn't possible. Just never seen or even heard/read of it happening.

Me either. I was just told that by a mechanic once and considering I am not a mechanic, I'll take his advice over my own assumptions. :)

Plus it is easier than rigging up some hose adapters or using duct tape to put the garden hose together with the inlet line.

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Verify that you are correctly plumbed, inlet to inlet and outlet to outlet. You might be trying to pump water in to the outlet side of the impeller.

HOSES ARE CORRECT!

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That's a tough one to diagnose without being there. I'm not familiar with Indmars. If the thermostat housing isn't sealed because it only has one bolt, then there's your problem. Or if one bolt didn't tighten.

If it was a Mercruiser I'd say you had the coolant hoses on backwards. Other guess is wrong impeller.? I don't know anything about Indmar pumps. Was there instructions with the new impeller and gasket? Find out what the o-ring is for!!!

How about when the temp hits 200 you say it stops squeaking. How low does the temp gauge dip when it stops squeaking? Only 180? Sounds like a themostat prob.

Does it take a normal amount of time to reach normal temp ~150? Or does it overheat quickly?

Everything is installed correctly and the impellar is an exact part# match replacement from the Malibu dealer!

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That's a tough one to diagnose without being there. I'm not familiar with Indmars. If the thermostat housing isn't sealed because it only has one bolt, then there's your problem. Or if one bolt didn't tighten.

If it was a Mercruiser I'd say you had the coolant hoses on backwards. Other guess is wrong impeller.? I don't know anything about Indmar pumps. Was there instructions with the new impeller and gasket? Find out what the o-ring is for!!!

How about when the temp hits 200 you say it stops squeaking. How low does the temp gauge dip when it stops squeaking? Only 180? Sounds like a themostat prob.

Does it take a normal amount of time to reach normal temp ~150? Or does it overheat quickly?

No it doesnt stop squeaking cuz it hits 200...it stops squeaking everytime it begins to suck water from hose and then squeaks as the water begins to stop circulating and back out of inlet hose. It doesnt overheat quickly...takes a bit to reach 180 and then once it gets over 200 it goes a little quicker. Like I said I boiled stat and it opened right at 160 but its running over 180...guage doesnt drop much as it takes on water either. I dont know maybe it is just not enough water coming in when the stat opens and I should just drop it in the lake and see what happens. The last thing I did was check the thermostat and thats when I broke the cover bolt off so I have to find a new stat housing first...only one on ebay for $80...mine is rusted really bad.

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The coolant diagram I saw shows the water entering the block and circulates within the block, ... until the thermostat opens;.. then it allows new water to circulate.

That is correct. If the empty block got close to 200° and then was filled with 50° water I would suspect that you would have a good chance of cracking a block and at the very least the pressure created by the steam would blow gaskets.

The water is under pressure in the block when circulating. It won't get in the oil.

Not so much. In a car some pressure is created but it's a closed system. In an inboard boat the cooling water is allowed to free flow into the exhaust riser and then out the exhaust, no pressure is created to speak of. Evidenced by the fact that boat heaters use the suction of the incoming water to circulate water through the heater core because there is not enough pressure in the "heated" portion of the engine to drive the water through.

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That is correct. If the empty block got close to 200° and then was filled with 50° water I would suspect that you would have a good chance of cracking a block and at the very least the pressure created by the steam would blow gaskets.

Not so much. In a car some pressure is created but it's a closed system. In an inboard boat the cooling water is allowed to free flow into the exhaust riser and then out the exhaust, no pressure is created to speak of. Evidenced by the fact that boat heaters use the suction of the incoming water to circulate water through the heater core because there is not enough pressure in the "heated" portion of the engine to drive the water through.

Ok so this fun and all but back to MY problems : )

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Ok so this fun and all but back to MY problems

Oh, YOUR problem? You're screwed. :lol:

j/k

First things first, you need to find a new t-stat cover. Sure sounds like a bad impeller or an inline clog. Pull the cover off of the raw water pump and bump the ignition and make sure the impeller fins are turning with the impeller hub. Then pull the hose between the raw water pump and the tranny cooler, debris that is clogging the tranny cooler can back flow back into the hose causing you to not see it if you just check the cooler. Also pull the hose off of the top of the tranny cooler and make sure that you can see all the way through the inner tubes. If all of that checks out I would probably try replacing the engine temp sending unit. If that went bad you may not have any problems with the engine, the gauge could just be getting bad info.

Edited by NorCaliBu
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No it doesnt stop squeaking cuz it hits 200...it stops squeaking everytime it begins to suck water from hose and then squeaks as the water begins to stop circulating and back out of inlet hose. It doesnt overheat quickly...takes a bit to reach 180 and then once it gets over 200 it goes a little quicker. Like I said I boiled stat and it opened right at 160 but its running over 180...guage doesnt drop much as it takes on water either. I dont know maybe it is just not enough water coming in when the stat opens and I should just drop it in the lake and see what happens. The last thing I did was check the thermostat and thats when I broke the cover bolt off so I have to find a new stat housing first...only one on ebay for $80...mine is rusted really bad.

Dumb questions but is the garden hose kinked? is it turned on all the way? 5/8" or 3/4" hose?

I do mine the same way with ( knock on wood ) no problems but I am running some good water pressure and a 3/4" hose out of the house. Sounds like your sucking everything out of the hose or something until it recoups again.

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Dumb questions but is the garden hose kinked? is it turned on all the way? 5/8" or 3/4" hose?

I do mine the same way with ( knock on wood ) no problems but I am running some good water pressure and a 3/4" hose out of the house. Sounds like your sucking everything out of the hose or something until it recoups again.

I am running a 5/8 hose and only had it on a little bit as thats what the Indimar manual states to do and that it didnt take much to keep it cool. I droped the thermostat housing off at the machine shop today and will just drop it in the water and check for proper operation there...hopefully there is no real issue.

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