Overheating?

[jammer99]

Please don't laugh (too hard) I'm already kicking myself over this one. I was working on my boat the other weekend, went to run it up and forgot the water and the earmuffs (can you say melted impeller?). Its a 1989 Merc 4.3 liter with an alpha 1 outdrive. Obviously I melted the impeller, thats fixed. The other problem I now have is the temp guage reads about 160 just sitting there and jumps to the red immediately on startup. What could cause this? I have a couple ideas and they aren't pretty or cheap to fix.<br /><br />Thanks in advance

 

[Haut Medoc]

Re: Overheating?

Welcome to iboats You sure you got the impeller right? You didn't forget the key that holds it to to shaft. Did it over heat before you worked on it?.....JK

 

[malaki mama]

Re: Overheating?

i do not completely get your explanation..do you mean your gauge reads 160 when the boat isnt even or hasnt even been running? and then jumps to the red when the boat starts?<br /><br />are you getting any water flow at all now into the engine.. you can pull the hoses and check flow?

 

[Dunaruna]

Re: Overheating?

If I understand this correctly, the guage is reading 160 with the engine OFF and cold, jumps to hot when you turn the ignition on, correct?

 

[jammer99]

Re: Overheating?

Correct!<br />The guage reads 160 with the engine OFF and jumps immediately to hot when I start it.<br /><br />I'm thinking<br />A. Bad sending unit<br />B. Bad Guage<br />C. All of the above plus a warped head from my own stupidity.

 

[jammer99]

Re: Overheating?

I'll pull the hoses and check flow tomorrow.

 

[malaki mama]

Re: Overheating?

okay.. then definitely need to check that gauge..<br /><br />was your old impeller all in one piece or broken up.. did you find all the pieces? Might the a clog somewhere.. how long was it running without water? did the engine overheat at that point? <br /><br />well anyway good luck.. might not be nearly as bad as ya think..

 

[Dunaruna]

Re: Overheating?

In regard to the guage problem, it is definetly electrical.<br /><br />Wether or not you caused engine damage with a bad impeller is a seperate issue.<br /><br />At the moment, all I can imagine is that you fried the sender.

 

[deputydawg]

Re: Overheating?

How long did it run without water? The engine itself should be able to run several minutes before damage occurs from heating. I have run irrigation engines for up to 5 minutes without water with no heating. Not recommended but sometimes things happen.<br /><br />How long does it take the guage to show hot? The engine should take 5 minutes or more running before they read hot. If it shows hot immediately after starting then it is in the guage system. <br /><br />Make sure what everyone else has said, the impeller is in the right way, the key is in the shaft, and all of the gaskets are in place. Also check to make sure you have water flow to the engine in case of a plugged passage.