Mercury "200" 20hp Cooling

[bjarnold]

When I am running the engine water comes out of the check hole under the engine pretty good but the engine casing around the head gets really warm and the water stays cold. Is this normal??<br /><br />Thanks<br /><br />Bill Martin

 

[Chinewalker]

Re: Mercury "200" 20hp Cooling

Hi Bill,<br /> Pretty warm is good, pretty hot is bad. Easiest way to describe it is if you can put your hand on the exhaust cover plate and hold it there without getting fried, you're good to go. If it's too hot to hold your hand on the motor block or exhaust plate, then it's time for a new impeller, or in some cases a partial disassembly to clean out the passages. The water tube feeds from the top of the block, so if you're getting a good stream from the pisser, you should be alright...<br />- Scott

 

[bjarnold]

Re: Mercury "200" 20hp Cooling

What is involved in cleaning the passages? <br /><br />Thanks<br /><br />Bill Martin

 

[dmessy]

Re: Mercury "200" 20hp Cooling

Cleaning the passages can be done but....<br />You have to pull the exhaust plate and head and go at it with a wire brush but you'll probably break off a few bolts in doing so and you'd have to pull the powerhead to get the bolts out and clean the bottom passages. Basically, have to disassemble the motor...<br />Is it worth it? Not in my book unless you have a definite restriction which it sounds like you do not. Keep the impeller fresh and a watch on the telltale and you'er good to go.

 

[bjarnold]

Re: Mercury "200" 20hp Cooling

My only concern is the cowling under the head gets hot and I can only hold my hand on it for a few seconds. But it still pumps out cold water.<br /><br />Bill