Could be a few things. First, are you sure that the impeller key stayed in place when you were re-installing the lower unit. If the key is missing, the driveshaft won't turn the impeller....i.e. no water. You could have a blockage in the cooling line, which you may want to test be shooting compressed air in. Either way, you're going to be dropping the LU. Hopefully it is something simple like those two issues.
Hard to say without checking it out myself....could be a blockage at the powerhead. Are you running it in a deep enough bucket of water? I would make sure that at least half of the lower leg is submerged in water. Some guys run the with barely the cavitation plate covered in water...not a good thing to do.
Well I actually took it to the lake and I was the only one in the boat so the water was right to the exhaust holes, I am gonna take it apart again tonight, but one thing I do know while I had it apart is I was able to blow through the tube without any restrictions I cleaned everything up good. I do know that there was some sand in that lower unit but I don't recall there being any in the tube that goes to the power head. How do I figure out if there is blockage up in there where the tube connects to the power head? again thanks for all of your help, I am getting a little frustrated but I am not the type to quit once I get going so I am off to take another crack at it.
I am hoping someone else will jump in and add some ideas. If the impeller key is in place and the copper waterline is not blocked, it could be a blockage in the water discharge tube on the powerhead, but I have no experience fixing that. The copper cooling line that comes off the impeller is hooking up to the connection at the base of the powerhead....correct? It is pretty hard not to line up if everything else is sliding in place, but if for some reason it isn't, the water could just be pumping into the exhaust leg and never actually cooling the powerhead, which might explain debris in the exhaust housing.
You may also want to post a question on the Ask a Member board at www.aomci.org or John's Old Merc Q&A board. Dave Bernard is an expert on both sites and would probably be able to guide you through it.
