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Raw water intake tube fell off, engine started smoking/overheating, need some advice.


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Hey guys,

I have a 99 Sunsetter LX, indmar motor (i believe it is a monsoon 340).

Today after we got done riding, i pulled the wedge up and drained all my ballast and wanted to take a WOT cruise (don't get to do that very often because we are usually wakeboarding or surfing). I was going about 40 MPH, almost wide open throttle and i noticed a lot of smoke pouring out of the exhaust (not white fuel smoke). I immediately stopped the boat and checked the dog house, there was quite a bit of smoke coming from the motor. Next part is important: When i opened the doghouse i immediately noticed the Outlet tube of the raw water intake had fallen off and was just pouring water into the bilge. I must not have tightened it enough when i replaced the raw water pump. I only drove about 500 yards at WOT, and probably about 45 seconds. But there was obviosly no water getting to the motor. The motor did not shut off by itself, and I did not hear an overheat alarm.

I cut the motor, and waited for the motor to cool down (it wouldn't start for about 15 minutes after, it looked like my temperature was almost to 200. Once i got it started again I idled to the dock, I didn't want to run it again for the night and do any more damage.

My main questions are:

What damage did I do, if any? I know it's imperitive that water gets to motor, but accidents happen.

Are there any procedures I need to take to fix any damage that was caused? Like I stated up top, it was not run for very long at all, maybe 45 seconds tops.

Please let me know what you know on this, I don't want to cause any more damage.

Thanks crew.

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My main questions are:

What damage did I do, if any?

Are there any procedures I need to take to fix any damage that was caused?

Please let me know what you know on this, I don't want to cause any more damage.

Thanks crew.

I would re attach the water hose, check the engine oil, and see if it starts. If it does, see how it runs, keep an eye on the oil and engine temps amd watch for leaks, run it around the lake and see what happens. You may have some damage or hopefully not. Damage could range from none, to shortened life, to cracked heads, to needs a full overhaul or replacement. No point in overhauling or replacing the engine if you don't have to. (Check you insurance policy, My boat insurance covers this type of thing)

Reminds me of the time I yielded to my boys request that I floor board my old pick up truck, made it 1/2 mile before the transmission failed. (Hopefully they still believe that there was some cause and effect)

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I would re attach the water hose, check the engine oil, and see if it starts. If it does, see how it runs, keep an eye on the oil and engine temps amd watch for leaks, run it around the lake and see what happens. You may have some damage or hopefully not. Damage could range from none, to shortened life, to cracked heads, to needs a full overhaul or replacement. No point in overhauling or replacing the engine if you don't have to. (Check you insurance policy, My boat insurance covers this type of thing)

Reminds me of the time I yielded to my boys request that I floor board my old pick up truck, made it 1/2 mile before the transmission failed. (Hopefully they still believe that there was some cause and effect)

Thanks man. I got it started back up and got it to about 10-12 mph to get it back to the dock. It ran completely normal when I was moving back to the dock. I'll check the oil and see how it runs at half throttle, and keep an eye on it. I don't think there was any cracked heads, and the fact that it was running normally at 10-12 makes me think (and hope) that it wont need an overhaul.

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Pure speculation on my part, but I'm thinkin' it's ok. Smell the oil, see if it smells burned. The exhaust tubes may have taken a shot.

Just curious, how many hours on your engine? Let us know how it goes,

Steve B.

  • Like 3
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When you fired it back up to head back to the dock, had you re-attached the intake hose? If so, how long did you wait before firing it up after the overheat? I hope a good while. Introducing cold lake water into a smoking hot engine is bad news.

I overheated an old Chevy pickup once and knew cold water into a hot radiator and block was bad news so I slowly filled the empty radiator with cool water with the engine running to try to slowly warm up the water as it was added....still cracked the block. It ran fine for the next 6 months, but the radiator looked like a chocolate milkshake. I just got lucky since it didn't ever pump water into the oil. I would flush it and put new water in every couple weeks until winter....:lol: I wish I had risked the rad and just filled it to warm up a bit of water then fired it up. I would say your engine is fine as long as the cold water being pumped into it didn't crack it. 200 degree won't hurt an iron block or heads.

The worst thing you can do after overheating an engine is get impatient and try to rush starting it. I won;t start an engine after an over temp situation until the gauge is back in normal operating temps.

  • Like 2
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I would suggest doing a leak down and compression test on it prior to deciding it's okay. Cracked heads or block on a boat are harder to diagnose since it is much harder to look in to the coolant to see what is happening, therefore a leak down test is a great diagnostic tool. As noted, check the oil for the chocolate milkshake, that is a quick indicator of trouble.

Iron blocks are pretty robust, if you truly did only get it to 200 deg F, it will be fine. The only misleading effect is that if there was no water at the temp sensor it will read much lower than actual, so that data may not be very valid. Temps do rise pretty quick at WOT, so think back on how long you did run at WOT. Much cheaper to correctly diagnose damage now rather than later when more damage could occur. Good luck, hopefully all is good.

In addition, I would look at all the exhaust hoses and the mufflers, uncooled exhaust will melt both the rubber hoses and exhaust pipes. The damage may not be visible externally so a quick peek inside them could save later damage.

Edited by Woodski
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I would suggest doing a leak down and compression test on it prior to deciding it's okay. Cracked heads or block on a boat are harder to diagnose since it is much harder to look in to the coolant to see what is happening, therefore a leak down test is a great diagnostic tool. As noted, check the oil for the chocolate milkshake, that is a quick indicator of trouble.

Iron blocks are pretty robust, if you truly did only get it to 200 deg F, it will be fine. The only misleading effect is that if there was no water at the temp sensor it will read much lower than actual, so that data may not be very valid. Temps do rise pretty quick at WOT, so think back on how long you did run at WOT. Much cheaper to correctly diagnose damage now rather than later when more damage could occur. Good luck, hopefully all is good.

In addition, I would look at all the exhaust hoses and the mufflers, uncooled exhaust will melt both the rubber hoses and exhaust pipes. The damage may not be visible externally so a quick peek inside them could save later damage.

I'll definitely look into the exhaust hoses and mufflers. What part of the hoses should I look at? The ones coming off the manifolds with the clamps holding them on? I'll have to look into all that testing, the boat is on a lift at the dock and it's difficult to get the boat out of the water. I definitely don't want any more damage.

As far as how long i ran it at wot for, it was no more than 35-45 seconds, I gunned it right off the dock, and went roughly about 500 yards. So it really was not long at all.

When you fired it back up to head back to the dock, had you re-attached the intake hose? If so, how long did you wait before firing it up after the overheat? I hope a good while. Introducing cold lake water into a smoking hot engine is bad news.

I overheated an old Chevy pickup once and knew cold water into a hot radiator and block was bad news so I slowly filled the empty radiator with cool water with the engine running to try to slowly warm up the water as it was added....still cracked the block. It ran fine for the next 6 months, but the radiator looked like a chocolate milkshake. I just got lucky since it didn't ever pump water into the oil. I would flush it and put new water in every couple weeks until winter.... :lol: I wish I had risked the rad and just filled it to warm up a bit of water then fired it up. I would say your engine is fine as long as the cold water being pumped into it didn't crack it. 200 degree won't hurt an iron block or heads.

The worst thing you can do after overheating an engine is get impatient and try to rush starting it. I won;t start an engine after an over temp situation until the gauge is back in normal operating temps.

I couldnt get the boat started (thankfully), for about a half an hour. My gauge was reading about 170 when i got the boat started and like I said, i waited about a half an hour. But I did reattach the hose before waiting. Luckily I'm in Florida, and the water temp was 77, Not sure if that's what you meant by cold water. lol

Pure speculation on my part, but I'm thinkin' it's ok. Smell the oil, see if it smells burned. The exhaust tubes may have taken a shot.

Just curious, how many hours on your engine? Let us know how it goes,

Steve B.

There are right around 400 hours, 389 to be exact. There was a burning smell when i opened the doghouse, It went away pretty quickly though. I'll do some investigating tomorrow.

Keep the reponses coming guys, i really really appreciate it!

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The impellar was replaced about 10-15 hours ago (came with my new water pump). Still think I should replace it?

Yes if you ran it dry for more than a second or two, if it is in pieces, check the transmission cooler for pieces of rubber

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Yes if you ran it dry for more than a second or two, if it is in pieces, check the transmission cooler for pieces of rubber

It was the outlet hose that was unattached, the pump was running, pouring water into the bilge. :(

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I couldnt get the boat started (thankfully), for about a half an hour. My gauge was reading about 170 when i got the boat started and like I said, i waited about a half an hour. But I did reattach the hose before waiting. Luckily I'm in Florida, and the water temp was 77, Not sure if that's what you meant by cold water. lol

That 30 minutes might have saved your bacon. :) Like Woodski said, a leak down test is a great way to put your mind at rest and be sure there is no permanent damage done to the engine. If that passes and the exhaust looks OK. Ski On!

BTW - No rubbing in the water temps in FL....we have a skim coat of ice now. :Doh:

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Oh, I got it, impeller should be happy as it was pumping water

Yep, it was pumping a TON of water, right into the boat, haha. Any ideas of why or how the hose came loose? I checked the tranny cooler screen a bout a week ago and there was no debris build up. My guess is that I just didn't tighten that clamp up enough when i changed out that water pump, and this was the first time i have even run the boat at WOT since then. Correct me if I'm wrong, but i feel like The only other thing it could be would be stuff stuck in the screen and the water pressure of that pump just forced that hose to come loose.

That 30 minutes might have saved your bacon. :) Like Woodski said, a leak down test is a great way to put your mind at rest and be sure there is no permanent damage done to the engine. If that passes and the exhaust looks OK. Ski On!

BTW - No rubbing in the water temps in FL....we have a skim coat of ice now. :Doh:

Good news on the 30 mins, it was a beautiful evening so i didnt mind sitting for a bit. How is the leak down test done? Is it something that could be done myself at the lake or would I need to take it someplace to have that test done?

About those temps... they got down to low 60's last week, but we had a week of 80 degree weather and that temp bumped right back up to mid 70's. I'm super blessed to live in a place where i can load up and board on December 10th.

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I dont want to scare you...

It was April in Seattle at 2am about 3 weeks after purchasing my first bu. I was driving the 7 miles home from a friends house at WOT. All of a sudden i started to lose power and the temp went to zero. No alarm no nothing. Shut the boat off. The hose on the tranny cooler partially came off (i had it apart earlier in the night because I was trying to find out why the heater wasnt heating up and thought there could be a blockage). The manifolds got so hot the nylon connectors blew off. I didnt try to restart the boat given i couldnt reattach the manifold hoses. I ended up getting towed home by my friends nautique...

Couple days later i replaced the impeller, and reattached all the hoses. I checked the oil and it looked fine. Took the boat to the launch and it hydro locked. Then i did the smart thing and took her to Paul at Bakes.

The end damage was blown head gasket, my heads had to be rebuilt. All the valves had to be replaced as they have mushroomed. One of my exhaust manifolds had to be replaced and the starter got toasted from the hydrolocking.

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I dont want to scare you...

It was April in Seattle at 2am about 3 weeks after purchasing my first bu. I was driving the 7 miles home from a friends house at WOT. All of a sudden i started to lose power and the temp went to zero. No alarm no nothing. Shut the boat off. The hose on the tranny cooler partially came off (i had it apart earlier in the night because I was trying to find out why the heater wasnt heating up and thought there could be a blockage). The manifolds got so hot the nylon connectors blew off. I didnt try to restart the boat given i couldnt reattach the manifold hoses. I ended up getting towed home by my friends nautique...

Couple days later i replaced the impeller, and reattached all the hoses. I checked the oil and it looked fine. Took the boat to the launch and it hydro locked. Then i did the smart thing and took her to Paul at Bakes.

The end damage was blown head gasket, my heads had to be rebuilt. All the valves had to be replaced as they have mushroomed. One of my exhaust manifolds had to be replaced and the starter got toasted from the hydrolocking.

Thanks man, but I am really hoping the fact that i only ran it ~500 yards, is gonna be a different result than 7 miles. Hoping!

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Also check your hose routing. I thought I had not connected the hose tight enough, but actually I had attached that hose incorrectly, and it was pulled by the rudder arm everytime i made a hard turn one direction. It finally pulled it loose and started pumping water into the bildge. I had put it over something that it should have been under, i think.

Anyway, worth a check to be sure you don't do the same thing again.

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I dont want to scare you...

It was April in Seattle at 2am about 3 weeks after purchasing my first bu. I was driving the 7 miles home from a friends house at WOT. All of a sudden i started to lose power and the temp went to zero. No alarm no nothing. Shut the boat off. The hose on the tranny cooler partially came off (i had it apart earlier in the night because I was trying to find out why the heater wasnt heating up and thought there could be a blockage). The manifolds got so hot the nylon connectors blew off. I didnt try to restart the boat given i couldnt reattach the manifold hoses. I ended up getting towed home by my friends nautique...

Couple days later i replaced the impeller, and reattached all the hoses. I checked the oil and it looked fine. Took the boat to the launch and it hydro locked. Then i did the smart thing and took her to Paul at Bakes.

The end damage was blown head gasket, my heads had to be rebuilt. All the valves had to be replaced as they have mushroomed. One of my exhaust manifolds had to be replaced and the starter got toasted from the hydrolocking.

2 am

New boat or new to you

7 miles at WOT

Your lucky damage was limited to your boat

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if the boat test articles are correct, my SSLXI will burn something like 20 gph at WOT. So at WOT I would burn 3 gpm. Assuming 40 mph at WOT, I would cover 7 miles in about 10 mins burning something like 30 gallons?

Edited by Bozboat
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if the boat test articles are correct, my SSLXI will burn something like 20 gph at WOT. So at WOT I would burn 3 gpm. Assuming 40 mph at WOT, I would cover 7 miles in about 10 mins burning something like 30 gallons?

Actually, you would burn 0.3 gpm so you would burn 3 gallons in 10 minutes.
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2 am

New boat or new to you

7 miles at WOT

Your lucky damage was limited to your boat

New to me boat. I was only about a mile into the trip. I never run full WOT, i dont go above 5000 RPMs but its close enough. Yeah I got lucky that it didnt catch of fire or anything. Abandoning ship in 50 degree water wouldnt not have been good.

And I know what you are all thinking and no I wasnt intoxicated.

The true lessons learned, I have the best friends anyone can have, the boating industry has the best people and support group you can ever come across, and having Paul and Bakes in my back yard is an absolute godsend.

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No reason to run these boats at WOT.

Lesson learned????

There's no harm in running these boats WOT, therefor why would the OP need to learn a lesson on that? If anything, the lesson to be learned here is to double and triple check your work. (tightening hoses) :biggrin:

To the OP, like others have said check the impeller for broken fins, check the oil for signs of water(blown head gasket or cracked head), and last, visually inspect your engine to the T. Check the heads and block for cracks. The reason i say this is because a boat with an open cooling system vs. closed cooling system( like a car) can run perfect and hold a good temperature even with a cracked block and cracked heads due to lack of pressure in the system. I know this from personal experience. I bought my boat over 4 years ago now and for the first three years i was running it as stated above without knowing it. It ran great, held a good temp(whether wake boarding, idling, or running WOT. After spotting a very slow leak this last year, i tore it apart thinking i had a blown head gasket. It turned out to be that both heads were cracked and had been JB Welded and repainted by the previous owner. :( After further inspection i found that the block was cracked right behind the alternator. So one long block later, here i am.

I will also add that i have always winterized the boat, including impeller change, and changed fluids. My oil never came out milky. So really my engine didn't show any signs of being junk until i actually saw the cracks for the first time.

If you don't see anything visually wrong with the heads or block and do the other things mentioned above i would bet you are in the clear and you should just take it as a freebie. :biggrin:

Edited by james11music
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