Re: Thermostat bad or weak stator fouling plugs?
Your engine sounds strong in the video. That 85 engine is a flatback. Should not be that difficult to get into the thermostat housing mounted on the exhaust adapter. I don't pull the powerhead on my 79 85 hp Johnson. On that older model (pre-VRO), you can loosen the lower cowl and move it around to gain access. It's the bubble back (140 and later 115 crossflow engines) that are hard to work on. It is possible that both stats are bad, but also possible something is going on with the nylon pressure relief valves. Check them out for heat deformation when you open up the housing. Your engine should come up to the 140 temp range when idling. Once you get up on plane and the pressure relief valves open, it is likely that your block/head temps will run at 115 degrees-even colder sometimes in the cold water you are running in. You will get some water out the exhaust ports at the top of the midsection at idle. When on plane, it should be two huge streams of water.
