1977 evinrude/johnson overheating after lower unit rebuild

M

marklhultine

Recruit
Joined
Sep 1, 2012
Messages
2
Hi all, my first time here! My 115 is overheating after leaving the dock. It idles fine, and has a great amount of water expelling from the exhaust ports. I can even troll for a bit before the alarm sounds. It is not a false alarm, this I know due to the steam that eventually will start coming out of the exhaust ports. Not a great amount, but obviously this unit is getting hot. I have removed the thermostat, and tested it in hot water. It does activate at about 165 degrees. My mechanic told me to just start changing gaskets until it gets better. Perhaps it is a head gasket, or .,... and I'm getting blow back to push the water back away from the head. Is there a test I can do to find the possible leak? I was told this motor's bottom end was rebuilt, including the water pump. I'm not sure as I have not taken that apart. However, with the amount of water coming out the exhaust, I must believe the pump is functioning as it should. Any ideas out there?

Thanks
 
fireman57

fireman57

Captain
Joined
Aug 24, 2004
Messages
3,811
Re: 1977 evinrude/johnson overheating after lower unit rebuild

Welcome to iboats. You could have a blocked water passage in the head, bad gaskets on the exhaust side, or a bad head gasket. If you have a spark plug that is washed clean, looks like new, then I would suspect a head gasket first. Those are easy to change. While you have the head off take a wire and run it through all the water jackets surrounding the cylinders. If you can find a small nozzle to attach to your garden hose that will help flush stuff out too. If it is the exhaust side it will take a little more time.
 
8

81_chapparel194

Petty Officer 1st Class
Joined
Aug 7, 2012
Messages
341
Re: 1977 evinrude/johnson overheating after lower unit rebuild

marklhultine said:
Hi all, my first time here! My 115 is overheating after leaving the dock. It idles fine, and has a great amount of water expelling from the exhaust ports. I can even troll for a bit before the alarm sounds. It is not a false alarm, this I know due to the steam that eventually will start coming out of the exhaust ports. Not a great amount, but obviously this unit is getting hot. I have removed the thermostat, and tested it in hot water. It does activate at about 165 degrees. My mechanic told me to just start changing gaskets until it gets better. Perhaps it is a head gasket, or .,... and I'm getting blow back to push the water back away from the head. Is there a test I can do to find the possible leak? I was told this motor's bottom end was rebuilt, including the water pump. I'm not sure as I have not taken that apart. However, with the amount of water coming out the exhaust, I must believe the pump is functioning as it should. Any ideas out there?

Thanks
Click to expand...
i had i similur problem and found i had crud build up behind my thermostats.. this was restricting my flow of water out of the exhaust system.. flushed out with a garden hose attatched to the thermostat hose nipple. before flushing it i wuld overheat in mere minutes 0f being on the hose running. after i cleaned it out i noticed immediately a change... oh and t-stats shoud be openng around ~140 or 145
 
B

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: 1977 evinrude/johnson overheating after lower unit rebuild

You could also have some bad water deflectors in the block.
 
C

Captmills

Petty Officer 1st Class
Joined
Aug 22, 2009
Messages
374
Re: 1977 evinrude/johnson overheating after lower unit rebuild

Had a problem with mine and found out the water tube was not inserted into the pump:redface:
 
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