8.1 Overheating quickly

Offshore35

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May 25, 2010
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Replaced impeller in my 8.1 GI-J 3 months ago. It sat until Saturday. It overheated within 5 - 10 minutes of cold start. Do I replace the T Stat? Any help is appreciated
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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First welcome aboard

when you pulled the old impeller, was any of the vanes missing?

when you replaced the raw water pump, did you mix the hoses up at the raw water pump?

did you check for water flow?
 

Offshore35

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May 25, 2010
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Old impeller was not visibly bad, just had 200 hours on it. The boat ran fine the 2 times we had it out prior to parking it in the garage for the winter. I changed it since I had just bought the boat.It then say for 3 months until Saturday, only other thing I can think of is I installed with the fins going the wrong way.

Hose diameters are different, so while it is possible it would be hard to get them swapped.
I will be looking at that one more time before I install the replacement for the replacement impeller.
I want to replace it since it got hot. It got hot enough the alarm sounded. So I always side on safe than sorry.
Just not sure if a T stat is in order or not.
 

tpenfield

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Jul 18, 2011
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I don't think you have enough information to isolate the overheating to the thermostat. You could remove it and put it in a pot of water heating on the stove to see at which temperature the thermostat opens (meat thermometer or similar)

If the t-stat starts to open at the prescribed temperature, then it is working properly.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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The vanes would flip themselves

Pull the impeller and look to make sure the new impeller is in good shape and not burned up
 

BRICH1260

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Jul 6, 2011
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Had the same problem once. Turned out I had two rubber O rings installed and was not getting a good seal, sucking air. Make sure that you only have one pump O ring installed and that it is positioned correctly.
 

Offshore35

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May 25, 2010
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It was suggested to me yesterday at the boat store while picking up a new impeller - again, to be sure the blue cap on the hose connection is tight. if air is sucked in it can cause an O/H condition.
Thanks to all that provided guidance. I will install and check things out later this afternoon.
 

Offshore35

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May 25, 2010
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Well first I would like to thank those that provided responses.
Second, problem solved. I replaced the impeller, again, confirmed the blue cap was tight at the hose connection and all is well.
 
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