35 Johnson overheating

[Steve L]

My 2000 Johnson 35hp 3-cyl. has been overheating sporaticaly for the last two seasons.It has overheated with 2 different thermostats. The impeller has been replaced and I just got a hefty bill for the replacement of the no. 1 & 2 pistons, Apperently due to the motor running hot. When the powerhead was apart the water passages were blown out and no blockages were found.After all this my Johnson dealer still has no idea why the motor overheats.Has anyone else had a similar problem ? I came across a previous post that stated this motor may have a water circulation problem ,in the cylinder head, from the factory? Any other ideas ? Thanks for your help. Diver- Down

 

[dragonslayer]

Re: 35 Johnson overheating

Have not seen any overheat problems with the 35 3cylinder powerheads. Don't know if I would have any ideas but do need more info.<br /><br />When is it overheating? At an idle, high speed, or both. What type of boat is it on?

 

[jegervais]

Re: 35 Johnson overheating

Here's something I've seen on a couple of those motors: Check the water intake screen installation. If it's installed backwards. At idle and slow speeds it can flow enough water to cool the engine but, the water flow at higher speeds is interupted and the powerhead can overheat. The flare (wide end) should be towards the rear of the gearcase.<br /><br />-John