QD19 Overheat Question – Update

[joecb]

A very timely discussion, I too have been looking for the info on drilling the auxiliary cooling hole, haven’t been able to find it yet. All hope lies with Garry to come to the rescue… again!

Joe B

[phil-b]

I thought the keyed to splined drive shaft changed in 1960 (QD21 -> QD21S) along with heavier gears.

[fleetwin]

Yes, at this point, I would go with mumble’s drilling advice. It will be easy enough to plug this hole if the fix does not work out. The only other idea would be to find a different mid section with the longer divider wall between the shift linkage and exhaust cavity, but it would have to be from another 58 model.

[beerman57]

OK, Saturday it gets drilled, right?

[chris-p]

That may help solve the problem. However, I personally would love to know WHAT is causing it!

Pull that plate as well, have a peek inside to see if the bypass port is plugged.

[beerman57]

I already checked it, hooked up hose to water tube and blocked off the water discharge enough to see water coming down the inside of the mid.

[fleetwin]

At this point, I would go ahead with Mumbles’ drilling advice. Yes, there may be some other issue in that midsection, but the collective knowledge base here can’t come up with it. I personally feel that a midsection with the longer divider between the exhaust and shift cavity would solve the problem as well, but it would have to be from a 58 model only. And, I’m sure you don’t have one "laying around", and if you did, it would probably have the shallow wall as well. Art’s theory about exhaust leaking around the sloppy shift lever makes some sense also, but I don’t know how you could easily "rebush" that shift rod hole.
So, go ahead and drill into that passage. Worst case scenario: you have to pull the powerhead and seal up the hole with marine tex/epoxy. No big deal. Again, angle the 1/16" hole downward into the shift linkage cavity.

[jeff-register]

I believe Garry stated to drill at an angle. Are we looking actively! Seems like a first year (1958) major change with a major mistake.
I thought it was odd not to have a pencil sized water exit hole from the beginning, but I’m not a Johnson expert by a far reach. I also thought a mid year change as well.

[Mumbles]

Has the temperature of the shift handle ever been checked with an infrared thermometer to verify it is running hot in this area? As we get older, our sensitivity to temperature changes. I’d hold off drilling anything until you’re certain it is too hot.

If you do drill a hole, there’s two things to consider. First, you are tapping into the motors cooling water supply system so the hole should probably be kept as small as possible to prevent bleeding off too much water and causing the powerhead to run hot. A 1/16" hole would be a good starting point and should be large enough if the pump is in primo condition. You’re not trying to drown the area with water, but just spray it. Second, the angle of the hole comes into play. If it is drilled aimed at the shift linkage, the hot exhaust gases swirling around in there might blow the spray away and down the exhaust opening. You might want to aim it forwards of where you want the water to go. Something like leading a clay pigeon before you powder it.

[beerman57]

Two things, first, I don’t really care about the shift handle being hot, I just mentioned it because it pertains to the midsection being too hot.
The second thing is, I thought drilling the hole was just for the purpose of cooling the exhaust and thus the mid, with the benefit of the shift linkage getting cooled too. Oh yeah, I pumped the grease fitting on the shift handle full of grease, that should help some.
I’m going to test the hole I drill before I put the P/H back on. It would be nice if the water sprayed out, but it will probably be more of a stream.

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