Re: 1982 150 poppet valve questions
Hi Dan;
The poppet operates on pressure exerted from the impeller. The pressure exerted from higher rpm's on the impeller has an affect on the water flow to and through the water passages. As water pumps through the heads, pressure is exerted on the t'stats while at the same time a separate passage to the top of the power head (to the plug at the top). If this plug were removed and connected to a hose that allowed water to flow freely, then overall pump pressure would be exiting the hose rather than through the t'stats (path of least resistance).
If you connected the hose to something like the relief valve, then what excess pressure in the water loop that couldn't be releast by the t'stats would be exerted on the relief valve. It is what it says it is.
Inside the relief valve is a diaphragm and water deflector that is activated internally by the pressure from the hose you've connected via a small channel between the relief cover and plate. You will notice a small vent hole on the relief cover that indicates air will be vented at some point. What this tells you, is the diaphragm is pushing outward (towards the vent), therefore water is pushing the water deflector out, relieving spring pressure and allowing water to flow through the cannel into the power head. The greater the water pressure, the further the poppet opens. At idle, the t'stats are adequate to relieve what pressure the impeller is producing.
There is also a neutral channel that relieves "some pressure" that ties back to the internal outlet for the poppet. All of this excess pressure (esp. created at rpm's greater than idle speed) exists out the exhaust chamber and benefits the operation by creating a wall of water within the chamber to eliminate steam pockets and reduce exhaust noise.
The t'stat circuits and the relief valve circuit serve separate functions and are in no way interconnected except how they are fed; et, the impeller.
For the t'stats, the temperature rating should be 143 degrees. This is the temp that makes them full open. They will still begin opening as lesser temperatures (120 as mentioned). The heat generated through the heads dictates their throttle position. You will have water from the tale-tale shortly after startup, as meager as it may be to start with. As the heads heat up from friction, this in turn heats the water and throttles the t'stat.
Remember that there are other passages that are allowing water to circulate (one being the pressure relief) even at low rpm's. By observing your temp. gauge and the tale-tale flow, should should be able to determine when the t'stats are at full throttle. You will have a less strong tale-tale stream at 120 degrees than you will at 143, however, any stream (strong or not) tells you that some water is flowing through the heads. How cool the heads are is projected through your temp. gauge, the only dependency you have while operating.
Good luck.
Capt. Mike
