Topic: 64 Johnson 5.5 hp Powerhead Base Gasket Problem

This topic has 11 replies, 7 voices, and was last updated 5 years ago by Mumbles.

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June 20, 2020 at 6:54 pm #206225
jerryswiss
Participant
CD-21A, new impeller, new powerhead base gasket. No water getting to the powerhead at all, gets hot running in tank. Someone told me there may be an issue with these gaskets, if you get the wrong one it restricts water flow. The one I have is OMC 313065 306205, is that the right one?
June 20, 2020 at 7:31 pm #206235
Bob Wight
Participant
US Member
That should be the correct base gasket. Some things to check for:

– did you also replace the impeller plate? Old one could be warped.
– did you seal the impeller plate to the gearcase housing? Sometimes, they will suck air and not pump water properly.
– check the water tube for blockage or obstructions
– you could have blocked water jackets in the block

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
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."
June 20, 2020 at 9:10 pm #206237
labrador-guy
Participant
US Member
Another couple things to check. Make sure the water in your test tank is above the water pump housing. Someone has posted on this website that OMC recommends to take the cover off the side of the lower unit when running motor in a test barrel.

dale
June 20, 2020 at 10:19 pm #206247
Mumbles
Participant
Did you make sure the copper water tube lined up and went into the rubber grommet on the pump housing correctly?
June 21, 2020 at 6:25 am #206257
billw
Participant
US Member
You said new impeller. What was the condition of the pump housing? If it was worn a lot, sometimes a new impeller won’t even pump as well as an old one, because they are not worn in together.

In a barrel, I think the water should be all the way up to pump level.

Long live American manufacturing!
June 21, 2020 at 11:09 pm #206355
fleetwin
Participant
US Member
Did the engine pump water before you did the water pump job, or don’t you know because you had never run it….If the engine pumped water before you did the work, then something you did or replaced is the issue. Did you use an OEM impeller, or aftermarket? I’m guessing you might have misaligned the water tube…
Yes, make sure the water level is up over the gearcase to exhaust housing joint…
That is the right part number gasket, but perhaps someone mislabeled it….
Are you sure you got the water tube properly installed inside the water tube grommet?
June 22, 2020 at 1:06 pm #206403
jerryswiss
Participant
Ok, I have tested this motor every way I can think of.

1. Lower unit off, put in bucket, drill on drive shaft. It pumps water even at low rpm.
2. Lower unit on lower leg, everything but the power head, drill on drive shaft. Pumps water up to gasket even at low rpm.
3. With thermostat out, it has been out all along, checked all water passages in head by pouring water in them and blowing with air hose, including hot water evacuation to the tell-tale. Everything seems open to me.

Hmmmm, why is this motor overheating?
June 22, 2020 at 4:21 pm #206426
Mumbles
Participant
You might have a leaky or blown head gasket allowing combustion gases to get into the water jacket. Combustion pressure is much higher than any water pump can produce and the gases will force the water out of the cooling system causing an overheat situation.
June 22, 2020 at 4:53 pm #206432
jerryswiss
Participant
Blown head gasket, how would you test for that?
June 22, 2020 at 5:38 pm #206435
crosbyman
Participant
Canada Member
do a compression test on each cyl.

0 compression usually means a busted gasket or lob sided readings like 80 40

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