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Overheating 25hp 4 stroke

K

kolincancer

New member
So let me start by saying i got stuck out in the kelp beds and overheated this motor causing the cylinder head to break. i have since replaced the head and i have resolved that issue which was allowing water to mix into the motor oil. Now im having a issue of the outboard overheating after only 30 minutes of run time I've even gotten it to happen while at high idle on the dock. I've just taken apart the lower unit looking for some kind of indicator of why this might b happening however i cant seem to find any. The pair of gaskets on the water pump are stuck on the metal plate however if it was that then there would have been water in the lower unit oil. Im stuck and have no idea what could be causing this and any tips on where i should go from here would be great.
The outboard is a 2017 25hp 4stoke Mercury
has brand new impeller
brand new head and base gasket
new cylinder head
no water in either of the oils
 
I think the cause is clogged cooling passages in the outboard motor that can become clogged with debris, such as sand, seaweed, or rust. This can prevent the water from flowing properly and cooling the engine. Try checking the cooling passages for any debris that may be clogging them.
 
yes it has a brand new thermostat. and the passages appear clear. i blew some vape thru it and it goes thru without any force required i also ran a large amount of desal thru it. the other thing i forgot to mention is the tell tale flows well until i start moving at which point it kind of gets weak. it has a dolphin to assist w planeing however it had this b4 having to repair the engine and it was never a issue.
 
Ive been doing some sensor testing and im getting results in kilo ohms when the manual only reads ohms. Ive had this result on the etc and mat. For reference my results
Etc
20c =3.11 kohms
80c=194ohms

Mat
20c=2870ohms
80c=.279ohm
 
Addressing the issue of overheating in your 25hp 4-stroke engine is crucial for optimal performance. Firstly, check the water pump for any blockages and ensure the impeller is functioning correctly. Verify that there's sufficient water flow through the cooling system. digital marketing
 
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