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TallRedRider

Thermostat edumacation, heater issues...

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TallRedRider

More to come on my recent boat woes, but I was curious to hear the crew's opinion on something.

First off, I trust the shop I took the boat to. They are a Centurion and Supreme dealer and local to me. They have always treated me well and seem plenty competent. My Malibu dealer is 120 miles away and my boat is long out of warranty, plus I never have really seen their shop, so I trust the local shop pretty well.

I hope that I can explain the issue without getting into everything...but its possible that things are related. One issue the shop found is that while idling the boat in the shop, it would never get above 140 degrees. So he concluded that the Thermostat was stuck open. My boat has always gone rock steady to 160 degrees and stayed there. Never more, never less. But whatever, so I allowed him to change it. Not a big expense.

Yesterday when i get the boat back, I notice that it runs at 160 degrees at idle, but goes to 180 degrees when wakeboarding at 3500 RPM. (HH motor). I also noticed that my heater sure did not seem so hot. But figured that was my imagination, and my feet and hands were too cold to tell how hot it really was I guess. Today I call to ask about the variation in temperature, and he mentions that he swapped the return line on my heater, and put it going into the engine instead of where I had it on the intake line. He says he has seen some problems with it there. I am more than a little irritated that he screwed around with the heater I installed that was working perfectly. And more bugged that he did not tell me. He is willing to swap the heater back to how it was, I just have to take it back tomorrow morning.

He confirmed that the thermostat that he put in was a 160 degree thermostat. He wonders if maybe having rerouted the heater hoses is the cause of the problem. I know for a fact it is the cause of my heater not being warm enough, but cannot understand how that might be the cause of my boat temperature varying while idling vs. running. The water temp was 46 degrees and outdoor temp was about 55, FWIW.

The questions for the crew are this:

Was it really the thermostat broken that would not let my boat get up to temperature while in the shop on a fake a lake?

Why does my temperature vary now, and didn't before?

Why is my temperature higher now than before?

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TallRedRider

This is the Venturi fitting that I had on the water intake. He spliced it out and rerouted the heater return hose to the engine.

http://www.bakesonline.com/detail.aspx?ID=1389

I hope for hell's sake he didn't lose the fitting, since it costs another $55.

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shawndoggy

Lucky for you it's only $41.50 from skidim! http://www.skidim.com/prodinfo.asp?number=H424

Other than that I dunno. I understand what you are saying though and I'm curious to hear the answer.

I think I'd be telling dealer man to put everything back the way it was (at his expense) unless you'd complained about something. If it ain't broke don't fix it.

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TallRedRider

So the current plan is for him to put it back how it was, then run the boat and see what the engine temperature does. He has agreed to do that for free. So I guess that means I have to go to the lake again next week. :)

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tvano

iirc my lrc won't make 160° at idle.

as soon as i start making rpm it will ramp right up there.

i would swap the heater back to your install and then see what temps you maintain.

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Bozboat

same with my boat, it will not hit 160 at idle on the trailer. It will eventually climb to 160 if I run it on fast idle, but then it will cool right back off as soon as it pops open it cools back to 140

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martinarcher

That little baby is the best part in my heater install. I would not run without it!

My boat also won't run 160 at idle in the trailer. The RPM on the trailer needed to get to that temp would flatten my garden hose like a pancake.

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TallRedRider

So even just above idle is not likely to be able to get the temperature up? I have never done it, but guys who flush with antifreeze say that they have to get the engine temp up first to open up the thermostat, right? So how do they do that on the trailer?

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tvano

So even just above idle is not likely to be able to get the temperature up? I have never done it, but guys who flush with antifreeze say that they have to get the engine temp up first to open up the thermostat, right? So how do they do that on the trailer?

that q. just opens up another can o worms discussion about how to properly winterize.

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Dexter

So even just above idle is not likely to be able to get the temperature up? I have never done it, but guys who flush with antifreeze say that they have to get the engine temp up first to open up the thermostat, right? So how do they do that on the trailer?

You'll have to cut down on the water flow to allow the temperature to come up, lots of pressure there. Pretty sure the engine manual mentions that.

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Woodski

There is a fair amount of bypass water flowing through the system, so when injesting cold water and at idle or low throttle opening, the boat probably will not make it up to tstat temps. The off throttle and injestion of cold water also cools the engine quickly, so bottom line, not a big deal. The Y pipe is pretty critical to keep the heater working as you noticed and depending on how the mechanic re-routed the hoses, it might also help the idle condition. Does not appear the mechanic fully understands the marine version of how the heater works most effectively as it appears he tried to plumb the return line to a port that has the same pressure as the input side so no water would flow through the heater core at idle.

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SmoothWaterMan

Along the same lines as the posts already, verify the new thermostat is the right one for your engine. It may require bypass holes in it, depending on engine model and year.

Peter

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TallRedRider

Update: Thanks for all of the responses.

The mechanic had called Indmar and confirmed that the engine is supposed to have a 160 degree thermostat. I do not have more information about the thermostat. He rerouted the hoses for the heater to the original configuration. The mechanic thought that the analog gauge was not as accurate as the digital gauge on the display. He thinks I should watch the temperature carefully on the digital display and get back with him on what that reads.

I was able to get to the lake on Wednesday. The air temp was 65, water temp in the low 40's still.

The engine gradually warmed up to 160 degrees pretty nicely. It would then stay there even while cruising without ballast.

I do load the engine up pretty heavy, and with stock ballast plus about 1200 pounds and with the power wedge down, the engine probably works hard. At wakeboarding speeds, the RPM's are around 3700 RPM with the Acme 1235 prop. When wakeboarding the engine then heats up to 170 degrees and then stays solid right there. When the rider falls, the temperature drops within 10-15 seconds back to 160 degrees, and stays there until back on plane. I again shared this information with the mechanic, and he thinks that is fine. He thinks that the thermostat is likely starting to open at 160 and then opens fully by the time it gets to 170 degrees.

I am still a little concerned that when I run water through it that is 35 degrees warmer, that my engine temp may reach concerning levels. Also when the air temps are 45 degrees hotter as well. At this point, without contrary direction from the crew, I will just have to wait and see as the temps warm up.

It was warm enough that I forgot to turn on the heater...but the hoses are where they used to be, so I am sure it is working right now.

Edited by TallRedRider

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TallRedRider

Along the same lines as the posts already, verify the new thermostat is the right one for your engine. It may require bypass holes in it, depending on engine model and year.

Peter

Would bypass holes make the engine slower to warm up? I would also think that would make the engine run cooler, not warmer, right?

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shawndoggy

Mine runs hotter than 160 under load too. Probably about 170 on the gauge. Idles at 160 and takes forever to get to 160 on the hose.

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hethj7

Mine always shows about 165-170 on the gauge, which who knows how accurate it is. I was concerned when I first bought it and checked all the hoses, screens, etc. for blockages and replaced the thermostat. It didn't change the gauge readout one bit, so I now just consider it normal and haven't an issue since I've owned the boat.

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wakedncsu

Mine is the same. At idle it holds at 160. When i'm under load it will creep up toward 170. And I also happen to know the computer will shut the boat down to limp mode at 180.

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TallRedRider

Mine runs hotter than 160 under load too. Probably about 170 on the gauge. Idles at 160 and takes forever to get to 160 on the hose.

Mine always shows about 165-170 on the gauge, which who knows how accurate it is. I was concerned when I first bought it and checked all the hoses, screens, etc. for blockages and replaced the thermostat. It didn't change the gauge readout one bit, so I now just consider it normal and haven't an issue since I've owned the boat.

Mine is the same. At idle it holds at 160. When i'm under load it will creep up toward 170. And I also happen to know the computer will shut the boat down to limp mode at 180.

That seems to be a consensus. I wonder if the problem is that my previous thermostat was broken and not opening properly, so I never used to get that extra bump over 160 degrees. I am not sure that makes perfect sense, as that if my thermostat was seized wide open, I wouldn't stay at 160 degrees either, especially in cooler water, wouldn't that overcool the engine? And it used to just be solid at 160 degrees no matter what I did...who knows, maybe I just wasn't watching it close enough.

I seem relegated to just watching it and seeing what happens as water and air temps warm up.

Thanks for all the input, everyone.

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shawndoggy

Well, I'll confess I'm not a big fan of the temp bouncing around like that. I recall on our 'bu it would go as high as 180 if the engine was heat soaked and then shut down... say you had a long surf run, then shut down to pick up a rider and floated a bit. It would come down within about 30 seconds after restart, but it did always leave me a little paranoid.

New boat doesn't go quite that high from the heat soak, but regularly runs above 165 when pulling.

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wakeboarder3780

I don't think anyone formally said this yet, but you were wondering if it was really a t-stat issue before - anytime your boat can't get up to operating temperature the t-stat is suspect and should be the first thing replaced so it's good that it was replaced. I ride in sub 40 water temps as well and my boat will get up to operating temperature, just need to putter around and warm it up a bit first. I find by the time i have on all the dry suits, life jackets, neoprene gloves, neoprene cap, the boat is already warm.

Is an engine really so fussy that it can only handle a 20 degree variance in operating temperature? 160 is the t-stat level, 180 is the limp mode? I find that surprising but by no means am I a mechanical expert. I tinker at best.

Edited by wakeboarder3780

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