Reply With QuoteCould be either, could also be the lower unit was fitted correctly last time too, only option is to remove lower, check fitting, and replace full water pump while it's apart, then check thermostats anyway, how long since they were checked?
"I have a 1984 Johnson 115 HP V4.
When last using it in salt water steam started coming from the tell tale outlet. When I reduced speed it stopped and water came out again. Each time I increased speed the steam returned.
Recently the lower drive unit was removed in order to pressure test the gearbox ( due to loss of gear oil ). The motor has been operated successfully in seawater on one occasion after that.
Could the problem be the water pump or the thermostats?"
Could be either, could also be the lower unit was fitted correctly last time too, only option is to remove lower, check fitting, and replace full water pump while it's apart, then check thermostats anyway, how long since they were checked?
Evinrude v4 water schematic.jpgWater restriction or loss to the power head . Could be pump or blockage. At low revs there is enough water pressure to circulate , but at higher revs it's virtually boiling the little water that is getting through. Have attached a drawing which shows the water tell tale only tells you if the pump is working. If there is water coming out the telltale , it is not necessarily circulating through the other water passages.
Thanks for your prompt response.Originally Posted by Noelm
About two years, Noelm, when we last replaced the water pump.
Your detailed response is most helpful Gon Fishun. I'll take your observations into account.
Drop the lower unit and force a garden hose onto the water pickup tube and test run the engine to see if you get consistent water flow at varied rpm's. If the problem is still there then the water pump is not likely to blame.
inspect the impeller and pump housing. Also make sure the guide tube that mates the waterpump to the water pickup tube is in good order and the black rubber is in the bottom of the guide tube.
Next will be to remove the thermostat/relief valve housing (usually a bugger of a job to get to the bottom bolts). Inspect the thermos to see if jammed open or shut. If they appear to be working then put them in a pot of water on the stove and observe that they open as the water gets hot. Inspect the relief valves and springs also.
If all is ok there I would be suspicious of a head gasket leak. Exhaust pressure bleeding through into the water galleries and forcing the water out. Conduct a compression test and see what results you get. All cylinders within 10% is desirable. Typical pressures around 130psi for that engine.
Also you can encounter problems where the water tube joins the powerhead. If all else has not resolved it then whipping the powerhead off (easy to do) allows checking the grommet where the water tube meets the powerhead.
Report back when you have had a chance to fiddle.
Cheers
[QUOTE=BM;1640784]Drop the lower unit and force a garden hose onto the water pickup tube and test run the engine to see if you get consistent water flow at varied rpm's. If the problem is still there then the water pump is not likely to blame.
inspect the impeller and pump housing. Also make sure the guide tube that mates the waterpump to the water pickup tube is in good order and the black rubber is in the bottom of the guide tube.
Next will be to remove the thermostat/relief valve housing (usually a bugger of a job to get to the bottom bolts). Inspect the thermos to see if jammed open or shut. If they appear to be working then put them in a pot of water on the stove and observe that they open as the water gets hot. Inspect the relief valves and springs also.
If all is ok there I would be suspicious of a head gasket leak. Exhaust pressure bleeding through into the water galleries and forcing the water out. Conduct a compression test and see what results you get. All cylinders within 10% is desirable. Typical pressures around 130psi for that engine.
Also you can encounter problems where the water tube joins the powerhead. If all else has not resolved it then whipping the powerhead off (easy to do) allows checking the grommet where the water tube meets the powerhead.
Report back when you have had a chance to fiddle.
Cheers
Thanks everyone for your advice. I'll report bad after my mate and I have had a chance to adopt your suggestions.
Posting Permissions