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My thermostat surprise


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I bought my boat very late in the season last year. And I noticed that sometimes the engine temp didn't make it to 160. So over the winter I bought a new thermostat.

I took the boat out a week or so ago for the first time this year. Water temp was 54 degrees and it never got to 150.

So this weekend I popped open the thermostat housing and what do I find?

Note: the picture you are about to see is scary. You have been warned!

13669734354_48cdbbf03c.jpg

No thermostat!!!!

By the way I used a "standard" small block chevy gasket for the lower interface. It fit fine.

Edited by eyekode
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With no Stat in place and still getting to 160*, its possible that the prior owner was trying to hide a cooling issue. The last motor I ran no Stat in was a 600+ HP BB, and it barely made it to 100* running consistant 5500 RPM.

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martinarcher

That's what my t-stat housing looks like right now since it is removed during winterization. I'm guessing someone used to do that to that boat but forgot to put it back in in the spring.. :Doh:

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With no Stat in place and still getting to 160*, its possible that the prior owner was trying to hide a cooling issue. The last motor I ran no Stat in was a 600+ HP BB, and it barely made it to 100* running consistant 5500 RPM.

Yup, I am worried about that as it did get to 160 sometimes!

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If you haven't already, check the transmission cooler for lake junk and impeller pieces

Will do! Thanks for the tip.

I am surprised at how small the hole is that feeds the thermostat compared to the size of the hoses.

Salem

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That's what my t-stat housing looks like right now since it is removed during winterization. I'm guessing someone used to do that to that boat but forgot to put it back in in the spring.. :Doh:

Why would you find it necessary to remove the T-stat for winterization?

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Why would you find it necessary to remove the T-stat for winterization?

Search is your friend Baddog, shame on you!! In short, so that you don't have to worry about the block not filling with antifreeze because the tstat wasn't open (warm enough yet).

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Search is your friend Baddog, shame on you!! In short, so that you don't have to worry about the block not filling with antifreeze because the tstat wasn't open (warm enough yet).

Doesn't need to be open as there is a bypass.

Sent from my iPhone using Tapatalk

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Search is your friend Baddog, shame on you!! In short, so that you don't have to worry about the block not filling with antifreeze because the tstat wasn't open (warm enough yet).

I can always count on Ndawg to correct my bad habit ways. I certainly don't want to re-open that age old debate, but if one does not add anti-freeze, the T-stat question goes away. Thanks for clarification

  • Like 2
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@eyekode: It is surprising as zone 5 noted you got as much temp as you did w/o a stat. I would give your system a very good check over and while at it I would replace the impeller (I have seen & experienced weak ones, did you happen to notice whether your boat seemed louder than it should have as the cooling water does act as a muffler). As noted, check and clean the inlet side of the trans cooler, you might have some impeller debris trapped there. Another spot for restriction would be the exhaust manifold to riser joint as those passages tend to be small and if corroded, lose area quickly. Good luck, the sporty is a great boat.

Did you install a standard auto parts thermostat in the boat? If yes, do a careful review of your water circuit to make sure that you have water going through the exhaust manifolds at all times even when the stat is closed. If you notice that you don't, you can drill 2/3 small holes in the outer ring of the stat to allow some water to bleed through (common practice on modified "hot" boats). Another downside to the auto parts thermostat will be rust as there is no antifreeze to inhibit rust on a standard non-brass stat. Simply means it won't last very long and if the water you are running in is the same as the previous owner, by the picture it is pretty hard, iron rich water. SkiDim has some good pictures of a marine stat for you to compare if needed.

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I have changed the impeller this year and the thermostat is the correct marine 160 thermostat. But I will check the inlet of the trans cooler.

Thanks for the details!

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If you haven't already, check the transmission cooler for lake junk and impeller pieces

Very good advice.

Same with the "you might have a hidden cooling problem" statement.

"The Official Tow Boat of the Fukushima Wake Games"

This is no joke.

Someone on here boats in a nuclear power plant's cooling lake and they stated the av. lake temp. is in the 90s or, so.

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Nope not Harris. Its cooling water stays separate from the main lake.

I think the lake he's referring to is Lake Anna in VA. Part of it is normal temp and part heated if I'm not mistaken.

That is for nuclear plants. There are several coal plants in the area that are heated.

Edited by jesutton3
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I see you have done something different with your hair Baddog

(looking at your avatar)

Yep got it colored and styled and lost the sweater.

Edited by Baddog
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I put her on the water with a new thermostat and idling the temp rose to a hair over 180 and I turned it off.

I checked all of the hoses and the trans cooler and there are no restrictions.

The CTS that sends to the dash is not original. I took it out and measured it with an ohm meter. The results seemed close: 2230 ohm at 80 degrees F.

At boiling it read 130 ohms which is about 230. So it is possibly just reading high.

I will replace the CTS and see if that helps.

But first a stoopid question: the thermostat housing is two pieces. I put the thermostat sandwiched between these two pieces with the cone pointing up. It actually will fit under the two pieces as well. Did I get it right?

Thanks!

Salem

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Yeah I believe you have it right. Should be sandwiched between the 2 pieces, cone up. For the heck of it I would leave it out again just to see what your get. You might want to get another tool to read the water temp, could even go to auto parts store and buy a cheap gauge.

Sent from my iPhone using Tapatalk

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Hopefully someone else will chime in to verify the cone up thing. I remember mine had hard to read stamping on it that pointed the correct direction.

Steve B.

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