I have a 1971 Seagull Forty Plus long shaft that has been in sheds for the last 30+ years. After cleaning the fuel system, replacing the spark plug and cleaning the connectors and points - it sprang to life! Wonderful! Picture attached. I noticed the water flow out the tell tale was not particularly good even at higher RPM's (see picture). Now the water flow has stopped. I backflushed into the water exit in the block and the water came out the exhaust. Shouldn't the water have come out of the slots in the water pump housing? Help! I'd really like to get the motor running for this weekend.
You may well have debris moving around inside the cylinder block cooling passages. I would suggest removing the cylinder head and giving the water passages a really good clear out. Gently heat the cylinder head bolts first, and carefully undo them. Once the head and head gasket is off you will be able to clean out the waterways with a thin screwdriver. It will give you peace of mind also.
Before pulling the head, I was hoping to find out if perhaps the water pipe could perhaps be the issue. Isn't that why the backflushed water came out the exhaust and not the water pump housing? I will also try to flush water using the slots on the water pump housing (haven't done that yet). Please keep the recommendations coming.
Yes, its worth checking the water pipe is correctly located in its hole in the water pump housing. However cleaning out the waterways is a well recommended piece of routine maintenance. I'd always suggest it is done. After a long time there could be all sorts of crud sitting in there.
Hmm
You could also have a cracked block, hidden by the exhaust tube so it will be difficult to see unless you strip it. It's been sitting for a long time so anything could have happened to it.
2 nuts at the top of the drive tube holds the engine to lower unit. Heat is your best friend here along with a rubber hammer.They are often a sod to separate due to localised corrosion around the feed pipe inside the pumphousing or at the base of the exhaust tube closest the pumphousing. Separate the 2 components and you'll be able to peek down inside the exhaust tube at the bottom of the block. If it's cracked.... CURTAINS. A new/replacement block will be the only way back onto the water.
Trying to relocate the feed pipe into the pumphousing with the exhaust tube fitted becomes quite fiddly if you're doing this job on your own. A second pair of hands helps with this. One to lift and hold, the other to fiddle. (and try not to get your fingers squashed in the process)
OR (the less intrusive method)
if you can, undo the small screw that holds the exhaust tube to the block, see if you can wiggle the exhaust tube downwards enough to gain access to the nut that attaches the water feed pipe to the bottom of the block. You'll be able to see if there's any cracks in there too.
At the very least, if all checks out ok then you'd be wise to get the head off for a closer look. (you'll be surprised what's in there after 30 years of inactivity) 4 bolts and plenty of heat with a good fitting spanner or socket.Touch up the block with some paint at a later date.
Picture attached. I noticed the water flow out the tell tale was not particularly good even at higher RPM's (see picture). Now the water flow has stopped. I backflushed into the water exit in the block and the water came out the exhaust. Shouldn't the water have come out of the slots in the water pump housing? Help! I'd really like to get the motor running for this weekend.