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1976 Mercury 110 9.8 Info and Help

F

flyguy90

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Got a boat and an old 1976 electric start Merc 110 9.8 hp. I changed the lower oil and the spark plugs and to my awesome surprise it started right up when I hooked it up to my battery.
I have a few questions about it though. When it starts up water comes out the pee hole within a few seconds. It runs out the hole for about 5-10 seconds pretty freely but then stops. Then another couple minutes it does the same. I'm afraid to keep running it to see if itll keep doing it or if itll continuously run. Is this normal or do I probably need to replace or rebuilt the water pump? Along with this, does this motor have a thermostat or is it supposed to pee water the whole time?
Next question is that there is a little threaded hole right by the water pick up under the fin. Just wondering if something is supposed to be threaded in this hole? I've attached a pic.
1102152022b[1].jpg
And last is simple. What ignition is on the 76? The thunderbolt?
Thanks for any help!
 
On that "little hole" there's supposed to be a stud coming through there with a nut on it--and it's gone! Bad news, for only two fasteners hold that LU on. DON'T run it on a boat until you fix it.

On the flow/ no flow condition, the exhaust exits right where the water is sucked in so, running in in a small barrel/ bucket, the exhaust can screw things up. Try a larger bucket (but AFTER you replace that stud!)

Jeff

PS: That missing stud may have simply fallen out--it happens. Try screwing in a long bolt and see if there's still some threads in there. (It's a 5/16 coarse.) If so, install the longest stud you can, screw it ALL the way in, and put a nylon lock nut on it.
 
Great info guys thanks. So the stud is the one holding the water vent? The other hole seems pretty small. Maybe smaller that 1/4 in. Could that be the exhaust?
 
For many , many years the nut / stud is the one that holds the water intake screen !!!-------Just looked at a couple of lower units and that wee hole may have been for attaching a sacrificial anode.-----Much like the 20 hp lower units.------I must say I have never seen a 9.8 with a sacrificial anode mounted there.-----And no it certainly is not for exhaust !
 
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Good idea to use one.-----I have never seen one installed there.-------Not sure if one is available for that.---------------There are a number of anodes available that can be bolted on through the cavitation plate.----------Johnson / Evinrude 9.9 one will work there.---See a boat shop.
 
Back to the water pumping issue, these motors have a very weak impeller. I would absolutely replace the impeller immediately before running it any further. They like to break fins off and push them up into the powerhead and clog ports. I would remove the lower unit, backflush the motor until you see a nice solid stream coming out the copper tube going down to the lower unit. Then replace the impeller with a new one. They are only $10-15 and should be replace every couple of years. Also another part that commonly goes bad is the plastic tube the comes out of the water pump to connect to the copper tube. These melt sometimes if the motor is run with too shallow of water from the exhaust of the engine.
 
pulled the lower unit tonight, the impeller was actually fine but I am probably going to replace it anyway. the tube to the copper was actually kind of melted. what should I replace it with? Do I need to get an actual matching part or just some rubber tube?
 
I would definitely replace the impeller even if it looks good and that piece of tubing will just pop right out. I would recommend buying the actual replacement part to make sure you get a good seal. You can find them on this or many other sites. That is good news that your impeller is intact and not broken into pieces and up in your motor. I have seen too many that all the fins were gone and jammed all over the motor. This is cheap insurance that you will have a good working pump.
 
The plastic part is nothing but a guide to get the water tube into the pump housing.---------The grommet / seal is in the pump housing below that guide !!
 
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