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1983 Mercury 7.5 no taletell after new impeller install.

C

clint_col

New member
Picked up a 1983 7.5hp Mercury outboard recently. Got it up and running well and also installed a new impeller. This is a non thermostat engine. After the new impeller install no water is coming from the tale tell. I have seen a couple spurts of water come out but not much. Just seems to be a lot of what is either steam or exhaust coming from the tell tale. It takes a few seconds for this steam/exhaust to start. Any ideas on what the problem might be? I am beating my head against the wall with this thing, Ive probably taken it apart 15 times. Thank you.
 
There is a plastic washer at the top of the water tube.---On severe overheat it melts and blocks water flow.----Remove power head and inspect.----Easy fix if it is the issue.
 
Got the power head off, everything looks fine. With the power head off I spun the drives haft with a drill while the lower unit was in water and had good flow up at the top of the water tube. I also used the garden hose with a small adapter and gently pushed water in from the tell tale and also through from where the intake tube enters the bottom of the powerhead. Had good flow in every direction. Hooked everything back up and same result, what is definitely steam coming from the tell tale with small drops here and there.
 
I replaced the gromet and gasket where the power head connects to the lower unit. Still no change. I did notice that when I spin the driveshaft with a drill while the lower unit is in water it flows well up through the water tube but there is no pressure behind it. It comes up out of the tube like 3-4 inches when spinning with the drill but if i put my finger over it there is no pressure behind it. Don't know if that's normal.
My next guess is a leak between the exhaust and water jacket so then the exhaust is pushing the water out of the jacket. Any ideas would be great, thank you.
 
Looked at the plate, didn't see anything. Replaced with an OEM impeller. Gonna try replacing the gaskets between the exhaust plates. I'll update later.
 
Welp replaced all the gaskets and still no water coming from tell tale. 😕 gonna order a new impeller kit make sure everything right.
 
How long are you letting water run when testing? On a couple of outboard motors I've had over the years, it's taken several minutes to apparently get all of the air out of the system and start producing a pee stream. I'd say give it a little longer to run in the barrel. Up to 2-3 minutes.
 
The crankshaft/vertical drive shaft spin clockwise when looking down.

Verify that you did indeed get the vanes folded in the correct direction and not backwards.

I have a 7.5. Water flows quick. Like maybe 10 seconds.
 
halbrodmann said:
How long are you letting water run when testing? On a couple of outboard motors I've had over the years, it's taken several minutes to apparently get all of the air out of the system and start producing a pee stream. I'd say give it a little longer to run in the barrel. Up to 2-3 minutes.
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Not too long. Worried about overheating. I did let in run a little longer at it would sputter water here and there but nothing I trust.
 
Droid said:
The crankshaft/vertical drive shaft spin clockwise when looking down.

Verify that you did indeed get the vanes folded in the correct direction and not backwards.

I have a 7.5. Water flows quick. Like maybe 10 seconds.
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Spinning the right way and Veins are in the correct direction. I ordered an actual OEM impeller kit. Thought the one I had ordered was OEM but they got me...
 
There are 2 different size driveshaft on these motors.----Did you measure the shaft?-----Water MUST be 8" above the impeller when running in a test bucket.----If it is a non thermostat model it should pee after about 3 seconds !!
 
racerone said:
There are 2 different size driveshaft on these motors.----Did you measure the shaft?-----Water MUST be 8" above the impeller when running in a test bucket.----If it is a non thermostat model it should pee after about 3 seconds !!
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I measured the drive shaft and it's the right one(456). Thanks for all the information and help fellas.
 
Got the new OEM impeller kit installed tonight. Fired it up and she pumped water! Definitely noticed better fitment with this kit. Thanks to all the people that helped out!!
 
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