Blocked Cooling Channels on a Yamaha Malta Outboard

[Boathook]

I had a go at using the search facility with no luck as usual. How do I unblock the water channells in a Malta cylinder head?
I have removed the thermosat and dug around which has helped but I require some chemical to disolve the, I persume, salt. It has been suggested coke would be good but any other suggestions ? or even links to other postings where this has already been covered.

 

[Birdseye]

I've always dug the crud out with a screwdriver blade.

 

[bobg]

You can try removing the water inlet pipe into the block and prodding it with a piece of coat hanger wire, but this will not address internal blocking. I fear you are facing an expensive repair job involving a major stripdown. This is why it is so vitally important to flush out a sea water cooled outboard in fresh water for a minimum of four minutes after every immersion in salt water. It's a pain, but so will be a repair bill for £100-plus.

 

[Guest]

[ QUOTE ]
You can try removing the water inlet pipe into the block and prodding it with a piece of coat hanger wire, but this will not address internal blocking. I fear you are facing an expensive repair job involving a major stripdown. This is why it is so vitally important to flush out a sea water cooled outboard in fresh water for a minimum of four minutes after every immersion in salt water. It's a pain, but so will be a repair bill for £100-plus.

[/ QUOTE ]

That flush out is not always so successful !! I've had 2 o/boards both block up even though they had religiuous flushes after use.

Onto how to unblock ... acetic acid ..... vinegar in fact. Especially if you can get the concentrated spirit stuff as we have out here ! Syringe without needle ... keep pumping it into the water OUTLET ... so filling the head ......... kep it uppermost for a few hours then roll over to let it drain out.
Then if you can inject a load of water (tap water) and then a high pressure air hose behind it ... you may find the softened crud then blows back along the system.

Once you have it freed up - a run in a drum with Fernox Central Heating system goo added will clean it out and keep it clean.