Johnson 9.9 Seahorse Impeller

[salmon sam]

I have a Johnson Seahorse 9.9 (probably a late 70's model). Model
#J10RLCOM, Serial #E6038505. It starts and runs well but there is very little water exiting from the cooling water discharge (pea hole) and it is very hot so I am concerned about some kind of blockage in the cooling system. A friend suggested I check the impeller assembly in the lower shaft. I am trying to access the impeller housing and have separated the shaft at each of two points but cannot access the bolts holding the impeller housing to the lower shaft housing. Any suggestions? Do I need to separate the entire shaft from below the powerhead housing? Am I on the right track? Are there any online diagrams I can refer to to get a better idea of what I need to do? Thanks for any help you can give.

 

[HighTrim]

Re: Johnson 9.9 Seahorse Impeller

Welcome to iboats.

That is a 1985. You need to remove the lower unit to service the water pump. You should really get yourself a factory OEM service manual, trust me, it will pay for itself a million times over. Be sure to flush the water line with compressed air, or the garden hose, while the lower is down, to ensure that there is no blockage in the cooling circuit. This is also a good time to change the thermostat as well.The following may help.




http://www.meegsonline.com/tmd/waterpump.wmv

www.themarinedoctor.com/videos/removecase.wmv

www.themarinedoctor.com/waterpump.wmv

 

[HighTrim]

Re: Johnson 9.9 Seahorse Impeller

Mr Wisners site should help you out as well

http://www.sschapterpsa.com/ramblings/Lower_unit.htm

http://www.sschapterpsa.com/ramblings/water_circulation.htm

 

[BaitThrower]

Re: Johnson 9.9 Seahorse Impeller

Yep check out LeeRoy Wisner's site mentioned above. I have an '86 15hp which is basically the same engine. You need to completely remove the lower unit to access the water pump. It's not too hard but there are a few things to do to check it gets put back on properly afterwards. It's not too hard to do once you have done it once.

I found when reassembling the lower leg, you need to have the leg in a vertical position as you tighten up the bolts. This helps align the copper water tube and grommet in the water pump much more easily and prevents the grommet flexing or collapsing as you secure the lower unit. If it does either of those, it may restrict water flow. And yep, check the thermostat too. I just replaced mine... Old one was cruddy and not working too well.

 

[salmon sam]

Re: Johnson 9.9 Seahorse Impeller

Thanks very much for the replies. I haven't had the chance to replace the impeller yet but thanks to your help and references I'm sure it will be easy enough for me to accomplish. Is there a library of videos to consult other maintenance tasks? I would like to see one showing how to remove/replace the thermostat. Thanks again.

 

[HighTrim]

Re: Johnson 9.9 Seahorse Impeller

Changin the t stat is a piece of cake. Your stat is in the lower portion of the outside rear water cover (very bottom), which is bolted onto the rear of the head. It is easier with the powerhead off, but who the heck would want to do that just to change the stat. It can be done easier. First take off the rear cover latch. You can now remove the t stat cover and then t stat to replace. When you are re installing the cover, put the bottom right hand bolt into the cover before you slide it into place or else you wont be able to do it.

May need your wife/girlfriend/daughter to help, as their smaller hands make it a bit easier!