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Mercury 20hp need help

A

archer

New member
"Hello just picked this motor

"Hello just picked this motor up. It's running great. But as you can see from the picture it has no outward indication of what year make model and hp it is.... I think its a 1960-1980 merc 20hp but would like to know a bit more than that. I can't ready anything on the serial plate and don't see a model number on it anywhere.

Can you please ID from the pic?

86853.jpg
"
 
update think i found the seria

update think i found the serial number.

1799661 (not sure about the 1 at the end was very hard to read) but the rest im pretty sure of.
 
"After a bit of searching I&#3

"After a bit of searching I'm pretty sure that I have a 1965 20hp Super hurricane.

As i said it runs great (started up on 3rd pull) F-N-R all shifted in and out smoothly.

I ran it for about 10 seconds to test, and quickly noticed that i was not getting any water out of a telltale or out of the exhaust port. do these motors take a while to start pumping water (do they only start pumping once engine reaches a certain temp? or do they pump constantly)

almost certainly gonna replace the impeller regardless, but just want to know for sure."
 
"Alex, I would agree that your

"Alex, I would agree that your serial number looks good for a 1965 model.

It should start pumping "almost" immediately (just takes long enough to get the water up from the lower end to the head before it comes out) and should pump constantly. Looking through an old manual and parts list, I do not see a thermostat on this model..

This is an "old" model with the Phelon magneto igniton system. So when you pick up your impeller, you may want to grab a set of points and just keep them on-hand. If it's running good now, you can probably wait until you lay the motor up for the season to inspect under the flywheel.

I would however, also change the lower gear oil when you get at the impeller. It's cheap insurance against a potentially costly problem..."
 
"Graham,

Thanks for the tip

"Graham,

Thanks for the tips. Do you have a source for the points? I tried oldmercs.com and no luck.

Also would you by any chance have a parts diagram for the lower unit of this motor (or something similar) I want to make sure i'm removing the right screws for changing the impeller.

Thanks in advance
Alex"
 
"Hey, you are really in luck -

"Hey, you are really in luck - Sierra part #18-5153 should work for ya. Andrew (who runs this site) sells them for less than 10 bucks.

You can just click on "engine parts - by brand" (upper right on this page) and look for "breaker" under the Mercury parts page..."
 
"update:

am working on taki

"update:

am working on taking the lower unit off in order to inspect and replace the impeller, from what I under stand there are 3 bolts

1) front from above lower unit (this on came out no problem)

2) middle above prop where water intake is (this one came out no problem)

3) back above rear of prop (the nut came off this one but the lower unit is not moving in this area)

basically the lower unit has come down about 1/4 inch in the front but is not budging in the rear.

any tips/tricks of the trade to work on this?"
 
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