Johnson 9.9 Seahorse thermostat

Ive checked my impeller assembly, cleaned out the cooling water feed tube, put things back together (with no spare parts) and I'm still not getting much of anything out of the pea hole. I think my thermostat must be clogged or something. I saw some helpful videos showing how to get to the impeller and I'm hoping there are videos showing the same for changing out the thermostat. Help please. Thanks.

Re: Johnson 9.9 Seahorse thermostat

I gave instructions on how to change the t stat in your other thread, but if you are getting insufficient water flow from the tell tale, changing the t stat will not change that. The tell tale is routed before the t stat. In fact, you actually get more pressure out of the tell tale BEFORE the t stat opens. That being said, your t stat may actually be stuck open, but who knows. I would change it none the less.

Have you tried cleaning out the tell tale line and nipple? Little critters love to build nests in there, restricting water flow. When you had the lower unit down, did you run compressed air or the garden hose up the water line, then back down like I suggested? That would of ensured there was no restriction before re installing the lower unit.

http://www.sschapterpsa.com/ramblings/Johnson 9.9_15.htm

Re: Johnson 9.9 Seahorse thermostat

You went to all the trouble of dropping the gear unit and pulling the water pump. Then put the old impeller back again. Foolish boy!

You dont say what year but the thermostat is #19 and the cover is #6 in THIS DIAGRAM of an 84 model

Re: Johnson 9.9 Seahorse thermostat

Make sure when you re-assemble the lower unit that the shft/leg is in a vertical position, then tighten the bolts up evenly in sequence a few turns each so the lower unit moves upward without it angling one way or another. This is after you ensure the water pipe coming from the shaft/head is seated in the impeller housing grommet for it etc etc.

It took me a few goes to get this bit right.

As for changing the thermostat, if it is a pre '87 model, the thermostat is located down the bottom of the block at the rear and is a pain in the bum to get at. You either have to remove the whole powerhead, or at least remove the cylinder block head so you can get the water jacket cover off. The darn cowling latch gets in the way!

Re: Johnson 9.9 Seahorse thermostat

BaitThrower said:

As for changing the thermostat, if it is a pre '87 model, the thermostat is located down the bottom of the block at the rear and is a pain in the bum to get at. You either have to remove the whole powerhead, or at least remove the cylinder block head so you can get the water jacket cover off. The darn cowling latch gets in the way!

Click to expand...

There is an easier way, see his other thread for tips on this.

Re: Johnson 9.9 Seahorse thermostat

HighTrim said:

There is an easier way, see his other thread for tips on this.

Click to expand...

True, but I found on my motor that I couldnt get the latch bolt out at all because the thermostat cover was in the way of it. I tried every which way to get the latch bolt out with no success, so next easiest way was to remove the cylinder head (good opportunity for a new head gasket anyway) ;-)

Maybe whoever owned it last put the wrong length latch bolt or assembled it incorrectly... not sure

Re: Johnson 9.9 Seahorse thermostat

Wasn't another issue with restricted water flow on the 9.9's a collapsed grommet on the water tube under the powerhead?