Re: Water out of exhuast
The tell tale tells you that your water pump is pumping water to the engine. On some Mercs, son's 150 for one, forget the year, the tell tale only spewed water after the thermostat opened and this tell tale told you that the powerhead was getting fresh water. Problem is you had to wait for the tstat to open....took several minutes depending upon ambient temperature.
Other Merc designs just plumb the water directly to the powerhead (tstat) and to the tell tale (in parallel) so you get water as soon as the engine starts and the water makes it up there. Bad thing about this design is that you don't know if your powerhead is getting cooled or not.....stuck closed stat problem for example.
Well, having experienced both types and having suffered through a stuck closed tstat on a 3 cyl 90 hp engine first time out with a used engine purchase, I will take the immediately available regardless. Having water at dockside (idle) tells me that the pump is working and the passages are clear. The powerhead has an over temp sensor that will sound the warning horn/dash light if equipped if the stat fails to open when it should. Good news here is that the stat is only used at low speeds. Merc uses a pop-off valve for high speed operation so you can accelerate to around 2500 or more rpm's and the engine will get cooled and the warning will extinguish.....until you get below that rpm again. The senario I just mentioned is what I did during the first outing with my newly purchased boat and was not only able to zip around the lake and see what the boat could do, but also get back to dock safely, and understood exactly what caused the alarm....that was in 2004 and other than change plugs and the tstat, haven't had a wrench on the engine and it still runs like a scalded ape.
The holes at the rear of the engine below the cowling are there for pressure relief for the combustion chamber. The exhaust ports on an OB are under water at dockside and were it not for the relief vents the engine would have a hard time starting into that back pressure if it started at all. Since they are located in the mid section, at the top of the exhaust tube, exhaust and cooling water both exit the engine via that midsection on their way to the thru hub in the prop and out. At idle and low speed there is a small volume, but at WOT you have a lot......soooo some water and gasses excape at idle and you get a lot at WOT.
Sounds like it is operating normally to me.
HTH,
Mark
