jbuote, thanks! The model number is 40373D. I believe it's the long shaft, and has the electric shift. I would definitely appreciate knowing what to get, if only to have on-hand.
F_R That would be incredibly good news -- I've been working every day on this boat and motor (Thompson Sea Lancer and Lark V) for half a month, and my family really would like to get out on the water before Fall. It's been stored in a garage by my father in law for 25 years, and we bought it from him.
I'm really not looking forward to tearing into the lower unit for now if it could be avoided, next spring I wouldn't mind renewing anything worn. Everything has to be ordered by mail here. there are no outboard repair shops nearby. It is taking forever to do this one dicovery at a time. Anyway I do want to get seals and gaskets to have on hand now.
So here's all I know so far re. diagnosis. I was able to start the engine yesterday after replacing all major ignition components. For water supply, I am using a Tempo fitting and pressure water to the pickup fin. That came with the boat. The engine isn't in a barrel. The water is coming from a pressure pump and hose on a nearby stream that definitely runs cold even in summer..
I was having trouble at first getting it to idle, but believe I have the low speed jet adjusted to sustain at what sounds like a slightly fast idle to me -- hard to tell with an open exhaust and no experience of this engine. Lots of water coming out of the lower exhaust port. A slow drip running down the leg out of the top port.
I haven't tried running it more than a fast idle for about 5 minutes at a time -- the slow drip out of the top made me worried. I kept checking the cylinder head temp with my hand, and it wasn't hot feeling. I mean I could hold my hand on it, so at least the outside was below 150 F.
I did see a video of one with a reently replaced impeller in a barrel being run fast, and it did have more water coming out of the top port -- and that's what worried me. But if as you say, no upper port circulation will be seen unless a thermostat opens, then indeed the constant cold water and fast idle may not be enough to show true impeller working.
Is there a way I can check the water pump operation without disassembling the leg? I also haven't checked the lower unit oil yet, I have been waiting for Type C oil (mail order again) to arrive. It looks to me like my father in law must have used 90 weight, because I found it in his spares kit.
The other worry for me is the Selectric shift. Fingers crossed that I won't find problems there. At present if I pull the shifter back into the SHIFT area the motor RPM is too low to sustain. I have to keep it in the START area.
I'm hoping this is just a matter of adjustment. Not sure how fast the engine should be turning at idle, and where that would be located on the shifter. Unfortunately the owners manual is very sketchy. I do have an optical tach I could dig out. It would be good to know what the idle speed should be for this motor. I have a manual, now, but haven't found that info yet.
Anyway, thanks for all the help here. Friendly folks onboard this site...