Evinrude 4hp Blocked Cooling Powerhead

[dek101]

Hi , I have a problem with my outboard overheating ,I have checked the impeller which is ok, as I will replace with a new one.The water tube running from the impeller to the powerhead is free flowing, I have removed the head and checked the water ways all seems ok, the problem lies in the water way leading from the Water Tube in to the engine block.I have tried flushing the water ways with a high pressure hose which was unsuccessful , do you know of any other method to unblock ie kettle discaler or other chemical treatment.

Thank You Dek101

 

[tashasdaddy]

Re: Evinrude 4hp Blocked Cooling Powerhead

Welcome to iboats. more info, please read http://forums.iboats.com/showthread.php?t=250879

 

[Vic.S]

Re: Evinrude 4hp Blocked Cooling Powerhead

An acid descaler is worth a try. Kettle descaler perhaps, a central heating boiler descaler based on sulfamic acid. Rydlyme if its available where you are.

Trouble is you've got to get it in there to be effective, but if its blocked you can't get it in there.

I think you have eliminated this as a possibility but on some models the grommet at the top of the water tube gets compressed by corrosion until it closes over the top of the tube. It is a recurring problem on my 6HP.

 

[dek101]

Re: Evinrude 4hp Blocked Cooling Powerhead

Hi, Thank You for your reply ,I will try your reccomendation of the central heating boiler descaler , the only concern I had was damaging the metal if I use anything too acidic I have checked the upper grommet which is fine,the problem definitely lies within the powerhead.Would dismanteling the block further help me gain access to the waterways?

Thanks dek101

 

[rupertmja]

Re: Evinrude 4hp Blocked Cooling Powerhead

You might get away with just removing the head, then clean out allthe channels you see. Otherwise, you'll have to pull the powerhead off (I just did one myself recently). The problem wasn't salt or corrosion, but bits of gasket goo that had broken off and blocked/restricted the flow.

 

[dek101]

Re: Evinrude 4hp Blocked Cooling Powerhead

i have left boiler descaler soaking in the powerhead waterways overnight, if this does not work i will try stripping the powerhead , a job i have never done is this a task which can be done by a novice repairer, any tips or hints to help me ?