15hp Water Passage Restrictors

[pierretheron]

Hi all, i have a 1987 15hp Johnson that i'm stripping and re-doing the rings. I burnt them as a result of a blockage in the cooling system. Some-one ran the engine dry at some stage a piece of impellar broke off and lodged in the cooling channels. I'm using a Clymer manual that makes reference to "water passage restrictors" and it shows an image of a few tubes in the blocks cooling channels when viewed with the head off.

My block does not have these restrictors, and i hope it's not linked to the overheating issues i've had. I did find one chunk of impellar, as mentioned above, but no dislodged restrictors. Does anyone know about these Water Passage Restrictors, do some models have them and not others?
Thanks for helping!

 

[OBJ]

Re: 15hp Water Passage Restrictors

The 9.9/15's don't have them. Just make sure the passages are clean and get as much scale out of them as you can. The scale and deposits on the passage walls can interfer with heat transfer.

 

[pierretheron]

Re: 15hp Water Passage Restrictors

Thanks for the help OBJ, i have just opened the block and all is well inside, just a few ugly water fungus's! What is that stuff anyway...

Cheers
Pierre

 

[OBJ]

Re: 15hp Water Passage Restrictors

Don't know Pierre. Never seen water fungus in a water passage. Wuzit look like?