1990 honda 9.9 overheating

Good day all
Have 1990 Honda BABS ser 1201188. Replaced Impeller,however there is very little water from telltale at idle speed. When I increase throttle, more water but not enough to cool engine,as steam starts coming from xhaust In very short time.Removed thermostat,ran engine ,same outcome. Blew air through pickup tube, nothing changes.Thinking maybe faulty head gasket but no water in oil. Would appreciate any thoughts or ideas

If your motor has overheating to any great extent...especially if there is discoloring, it is possible that it is the head gasket....but....you did not say that the motor ran bad, so I will assume that it is otherwise running ok, at least until hot....

First check the thermostat and make sure that it is opening and that the passage is not blocked by debris.

If it had a bad overheat, the most likely problem area is under your powerhead. Notice part #18. http://www.boats.net/parts/search/Honda/Outboard Engine/1997/BF9.9AM LA/OIL PUMP/parts.html It is both the seal for the exhaust tube and the water intake tube. If the motor gets real hot, that seal melts, gets brittle or cracks and as you can see the exhaust will counteract the flow of the water.

It has been a while since I have had one of these power heads off, but you will need a powerhead gasket part #1 http://www.boats.net/parts/search/Honda/Outboard Engine/1997/BF9.9AM LA/CYLINDER/parts.html

There are a couple of other seals under there that you may want to change too, while you are there. I would recommend getting a good manual and just follow the instructions for removing the powerhead....it is not a terribly hard job. Take a lot of pictures, so you know how to run hoses and wiring, etc when you put it back together.

Mike

Hi Mike
Tks for reply.Have checked sites you forwarded. Will run motor in tank with no thermostat, and cover off to see If water gets up to housing. keep you posted. Really appreciate your help