Johnson qd-20 cooling question

[hondaatc]

Hey fellas i just picked up a qd – 20 the guy i purchased it from said he had recently replaced the impeller after only a few short minutes of running it in the bucket i noticed it spraying water out of the exhaust port like normal but it wasn’t much of a spray and it wasn’t steady the head was hot to the touch so i removed the thermostat housing cover and thermostat started the engine and nothing pumped out i did notice water also coming out of two holes on the lower unit ( see photo .. red circle ) this is the first outboard i own with these holes  also saw water seeping out of the shift linkage access cover any advice or info would be appreciated before i start removing and inspecting the impeller… thanks

[bobw]

You will normally see water coming out of those two holes on the side of the lower unit.   There will also be water in the exhaust stream and if it’s seeping out the shift linkage door, you just need a new gasket on access door.    If you pull the lower unit to check the impeller, check to see if the impeller plate is sealed to the gearcase housing – if not, they will sometimes not pump properly.   Also, with the lower unit removed check to see if the water tube up to the powerhead is clear (not obstructed) and see if water will flow up the tube thru the powerhead.   Finally, there could be an obstruction in the cylinder head water passage preventing a full flow of water.   These are some of the things I have found in the restoration of my QD-19 and QD-20 motors.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

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hondaatc

[hondaatc]

Thanks i will definitely check that out i did use my garden hose and sprayed water into  the thermostat housing and water came out the exhaust hole

[bobw]

One more thing I just found on my FD-12 restoration – when I pulled the lower unit I found the last person in there before me didn’t get the water pump grommet and water tube aligned correctly when they installed the lower unit.   The water tube grommet was mashed down on one side and that will prevent the proper flow of water.   See attached pics.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

1 user thanked author for this post.

hondaatc

[hondaatc]

Thanks again I’m hoping to have time to pull it apart this weekend hopefully its something like what u have found

[billw]

When you run it with the thermostat cover off, a LOT of water should come out. In addition to the many good tips of BobW, I would add that, if someone “replaced the impeller” but didn’t notice a badly worn impeller housing, sometimes they will pump WORSE with a new impeller in a bad housing. This is apparently because over time, an old impeller sort of form-fits the worn housing to some extent. A new one won’t fit the wear patterns as well.

Long live American manufacturing!

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hondaatc

[Mumbles]

If the impeller was changed but no water is coming out of the thermostat location, that indicates a blockage somewhere between the pump and the upper powerhead.  Quite possibly the old impeller was broken and not all of the pieces were accounted for  when it was replaced.  A piece of impeller vane can be lodged in the copper tube leading to the powerhead or could be caught under the block or in the passages under the exhaust cover.  Either way, the powerhead should come off  to find the blockage.

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hondaatc

[dave-bernard]

try forcing air or water up the water tube. see what happens. can’t hurt.

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hondaatc

[hondaatc]

Thanks fellas I’m gonna  Tear into it soon looks to be a nice outboard besides that

[Author]

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