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lewistonskier

Overheated, then wouldn't start

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lewistonskier

This is a long ordeal, but I will put it all so as to hopefully get the best advise. Two years ago, my alternator went out. I replaced it myself in time for a weekend camping trip, and everything went great until the last morning when I saw a tone of white steam or smoke coming out the back. My wife was driving, so I never saw the temperature gauge, but I was concerned with what was happening and thought it might be over my head, so I took it to the shop (3 and a half hour drive, and 2 week waiting period just to take it, and another three weeks before they could work on it). They found that it was only an impeller issue and replaced it. Next time out, everything seemed to work great, and we had a good day on the water. Went to start it the next day (we were camping again) and it cranked great, but there was no spark. Eventually traced it to the electronic conversion inside the distributer and replaced that, along with the cap, rotor, plugs, and ignition coil as skidim tech support told me that I had the wrong one. That summer was cut short as my wife got pregnant with out third kid, so all the replacement was only used to winterize. Last summer, the boat had to sit and didn't get used at all due to the complications that occurred with the birth of kid number 3.

Now we're to this year and my current problem. 10 days ago, we were on the launch ramp, started the engine but stayed on the trailer as I wanted to run it for a while given that it had sat for so long. Things sounded great, but when we put it in neutral, it would cut out. This is normally not a huge deal, and stops once things are good and warmed up. After about 10 min of running on the trailer, the engine temp had gone up to a little over 180 F. The engine cut out again, and when we went to restart, it cranked weakly, and then wouldn't turn over. It sounded like the battery had died. I switched to the other battery, and the same thing happened. Weak cranking, and then wouldn't turn at all. I assumed that it was somehow a battery issue, or there was something wrong with the starter. When we got home the next day, I charged the battery, and it fired right up on the first try. I then started it up every day between Friday and Thursday (three days ago) on the hose and it always fired up on the first or second try, and ran great. Launched on Thursday, headed out in the middle of the lake, saw that the engine temp was rising quickly, getting above 180 F again at high RPMs. I wanted to see what it would do at idle speed, so I pulled it back and it quite as soon as I put it in neutral. Went to try to restart it, and it did the same thing it had done on the ramp the week before. Cranked weakly, then wouldn't turn. When the key was turned, it showed the temp get as high as around 200 F. We sat for a bit with the engine cover open to let it cool. To get the hot water out, I drained the water out of the block, which had plenty of water in it, and the exhaust, which had very little water in it. After I drained the water, the engine temp got down to about 165/170 F and I tried to start it again. It cranked, and started, though with a little trouble. I drove back to the ramp at idle speed, and the temp stayed right at 180 F. The engine did cut out once at the dock, but it restarted fairly easy. When we got back to our campsite, I pulled the impeller to look at it, and it looks pristine. I pulled the thermostat and it was incredibly rusted and corroded. I'm sure that this needs to be replaced, and assume that it is contributing to the temp problems. What I need to know, is if the engine temp is the cause of the weak cranking, or if there is something else I need to be looking into. It would seem that they have something to do with each other since it started after it cooled, but I've never heard of a slightly overheated engine not starting. Or maybe the temp was higher than the gauge was showing? Would an engine of my vintage have some sort of protection? Is my started going bad, too? I'd really like to get this figured out, as if I don't have a working boat soon, I'm probably going to have to sell it, as it has been almost two years since I've had a truly successful outing.

Other things I noticed along the way. It is a crank type raw water pump, and the impeller housing was hot to the touch. So was the thermostat housing, and all of the water hoses after the water pump. The exhaust hoses were also very hot, though I didn't see any melting. When we first opened the engine compartment after it quite, there was steam and/or smoke coming from off of several places. It was all white, nothing black. When I run it on the hose, the water seems to be coming out the exhaust fine, but if I go any higher than about 2500 RPMs the water gets very hot to the touch. The engine is a Commander 351, and is in a 1986 Sunsetter.

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dlb

Check the screens in the transmission cooler to make sure the water flow is clear through the system. It sounds to me like this is a water flow issue and once the motor heats up to high it goes to safe mode. Also, since your impeller housing got hot again I would replace the impeller again as well. You may have seared it so it no longer will pull water through. On a hose the pressure will push water through.

See if it will suck 5 gallons from a bucket in 15 seconds or so. If it will your impeller is fine.

Edited by dlb

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REW

Replace the Tstat and clean out the system. I agree with the above, you are not flowing water properly.

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lewistonskier

Thanks for the replies. I will do a bucket test after I get a new Tstat (tomorrow). I checked the impeller after we were back in, and upon visual inspection, it looked fine. Would an engine of my vintage have a "safe mode?" Also, when I get a new tstat, can I get one from an auto parts store, or do I need to go Marine specific from skidim? I know that I can get the water flowing and the temp back to normal, I'm most concerned with is the high engine temp the reason that it won't start. Right now, I have correlation, but I'm not entirely sure I have causation. Maybe there's no way to check until I have the water flowing properly again?

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tvano

go w a marine t-stat.

automotive is what was in there (all rusted).

if the raw pump body is hot you are not pumping water.

make sure that the valve at the hull pick up point is open (if your vintage hull has that valve).

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RTS

^^^^ This.

Raw water cover should never be hot...or even warm. Should be cool to the touch. The pump is not pumping for some reason.

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lewistonskier

I have taken the tstat out, am I going to hurt anything if I start the engine to test the impeller suction? Should I disconnect water pump output house from the tstat housing and let it drain into the bilge or something similar?

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REW

I have taken the tstat out, am I going to hurt anything if I start the engine to test the impeller suction? Should I disconnect water pump output house from the tstat housing and let it drain into the bilge or something similar?

you will not hurt anything, however the engine will not come up to temp. at least shouldn't.

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lewistonskier

Just did the bucket test. I left the hose on full as I sucked the water out. Anything above 2500 RPMs and it was sucking water faster than then hose could keep up with. I'll order a marine tstat from skidim. While it was sucking water, the temp gauge didn't more (ran it for about 5 min, nothing too fast). The exhaust manifolds and exhaust hoses were (i thought) incredibly hot. There was even a little steam coming off the hoses. Is this normal for what I was doing? Water was gushing out the exhaust, so it seemed that things were keeping up. I"m running out of daytime today (i work the night shift and have to go to bed soon) so I haven't fully checked for blockages, but it seemed the way the water was running through that there was no blockage. Without the tstat, was it sending most of the water to the block instead of spreading it out? Any other reasons?

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dlb

Sounds like a thermostat issue. If everything flows fine get a new one. NAPA, Autozone is fine just get the correct temperature one.

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Steve B.

Sounds like there is still some issue. Exhaust should not get that hot when it is sucking so much water.

And with no thermostat at all should run very cool. In other words, the thermostat is not restricting at all, because there isn't one.

Steve B.

Edited by Steve B.

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lewistonskier

If exhaust should not be getting that hot, what type of issue should I be looking for at this point? Would it still probably be hose blockage? Can the exhaust manifolds themselves be clogged? I will get a new tstat, and check the hoses, but if the exhaust is still getting that hot, what should my plan of attack be?

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Steve B.

A thermostat really is just a restrictor. When an engine is cold, it restricts the flow so the temp comes up to get a good combustion temp.

After the engine is warm, the thermostat really is there just to maintain temp. Not to direct water flow in any direction.

Water coming out of the transmission cooler is essentially free flow to the top of the thermostat housing. So, it is essentially free flow to the exhaust, even if the thermostat is closed (to the engine).

As far as the exhaust, I'm guessing corrosion is making it difficult for water to get thru all the passages. Worst case scenario is you have to first, remove the "uprights" and inspect them.

Good luck,

Steve B.

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JasonK

I agree it could be corrosion blocking the exhaust passages, making them hotter than normal. Pull the riser off and inspect it, replace the gasket.

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tvano

i'm going to say it again because with a quick re-read i didn't see where the op responded to it: check the trans cooler. check it again.

90% of the cooling problems are impeller or debris accumulated at the trans oil cooler.

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lewistonskier

I went out today and disconnected every hose from the intake to the end of the upright. I couldn't find any debris along the way. I started hooking hoses back up one at a time and would start the engine to make sure there was output. When the hoses that go from the tstat housing to the upright were showing what I thought was good output, I left the engine running and held a garden hose on full up to the upright input. That was keeping it cool to the touch. I turned off the engine but left the hose there "flushing" the upright for quite some time. I repeated on the other side. When I hooked everything back up, I was running the engine with my hand on the upright at about 2000 RPMs which I couldn't get close to doing before. When I had originally pulled the drain plug out of the upright, some sand/small rocks came out with the water, so I'm thinking that the pressure/volume from the hose was more than the impeller could force through, and that freed everything up. Does this sound plausible?

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RTS

Only way to tell is get on the lake and see if everything is still OK without the 'assist' from the garden hose pressure. And small rocks could have been enough to block he flow you need.

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shawndoggy

you could try backflushing from the raw water pump with the hose. (remove intake hose from raw water pump, stick hose in there, turn to full blast).

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Michigan boarder

i'm going to say it again because with a quick re-read i didn't see where the op responded to it: check the trans cooler. check it again.

90% of the cooling problems are impeller or debris accumulated at the trans oil cooler.

lewistonskier - did you do this? Here's how you do it: Pull the hose off of the transmission cooler. Look up into the end of it where the water flows in. There is a screen there. That screen could be plugged with debris too (old impeller pieces).

I apologize if you already did exactly that, reading thru this it does not sound like you checked that screen.

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lewistonskier

Yes I did. Sorry for not saying specifically. That was among the things I did for sure today when I pulled all the hoses. Nothing in there. Thanks for keeping me on point.

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Steve B.

Any update?

Steve B.

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lewistonskier

Not yet, I put in the order for a new tstat and got a call today that it is on back order. I'm fairly certain that after I got the risers flushed out that I got the problem solved. I do plan on flushing them out with vinegar as well when I get a chance, just to try to get them good and clean.

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shawndoggy

While you are doing the vinegar flush, might as well do the block too. I was amazed at how well vinegar takes care of mineral buildup.

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lewistonskier

do you remember how much vinegar it took? I guessing around 5 gallons? How long should I leave it in for? With vinegar, I' assume that you can't leave it in too long, but you know what they say about people that assume...

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shawndoggy

Yeah five gallons for the whole engine and exhaust manifolds. I very scientifically "left it in overnight".

Here's what happened once I got the vinegar topped off to the thermo housing:

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