Evinrude Exorcist needed…

[twostroke]

I’m working on a buddy’s 1957 Evinrude 7 1/2 (Model 7523? Someone has thoughtfully knocked the tag off the transom clamp…). He bought it offa’ Craigslist with the story "water pump has been replace but won’t pump water….:" When I initially took it apart, it looked like they didn’t get the copper tube in the pump housing properly, so I pulled the pump apart and checked…impeller ok, plate in correctly. Put it together, fire it up….a few spits of water initially (10-15 seconds, maybe) then nothing (all gears work…). I’ve had this apart and together three times….and cannot find ANYTHING amiss. I’m missing something stupid…this is not rocket science… I’ve run plastic string trimmer line though the water passage/tube (no blockage), water pump is correctly assembled and in good shape, housing is not damaged, drive pin is in the shaft, impeller IS turning when shaft is turned (I checked…), powerhead base gasket is good, and I’m thinking (dangerous act..) this is old enough that it can’t have a thermostat that’s stuck. It’s just an old cheapie that he wants to use on a duck boat…but the old brute runs really nice, and now I’m irritated enough (and stubborn enough) that I’m NOT gonna’ get outsmarted by an outboard motor that as old as me.

I thought about putting the lower unit in the tank sans powerhead and spinning it with my big 1/2" drill….but that’s getting perilously close to mixing electricity and water. When you have bad luck and know it, you don’t take chances.

Any input would be greatly appreciated…Thanks!

Jim

I say "pardon me" a lot. I had a 20H, then raced open mod sleds.

[outbdnut2]

You probably already know this, but are you putting enough water in the test tank? I know a guy who trashed 2 impellers on a 1950s Evinrude because he had water just covering the water intake – you have to have water several inches above the intake to get the pump primed and working.
Dave

[twostroke]

Yep. I learned that lesson the hard way back when I had hair. I’ve always given those old OMC’s 8-10" of water above the cavitation plate. Thanks, though….because it’s gonna’ be something stupid like this and I’m gonna’ kick myself….

I say "pardon me" a lot. I had a 20H, then raced open mod sleds.

[wedgie]

I would do as you suggested with the drill, but use a cordless one for safety sake.That’s what I have done.

[Tom]

Pump inlet clear?

T

[bigrichsoldoutboard]

Have you had the head off to see if the water passages are clear may have to be cleaned they sometimes get clogged from sand, salt corrosion ect

[twostroke]

Pump inlet is clear…I did check that. Haven’t pulled the head yet….I’ll try the cordless drill deal and see if I can get it to prime up before I pull the head. Obviously I can only see a very little of the coolant passages, but all that I can see is really clean.

I say "pardon me" a lot. I had a 20H, then raced open mod sleds.

[crosbyman]

Do pull the head and drive the shaft as suggested to see if water shoots up from the pump out… up the water tube at the top
https://www.youtube.com/watch?v=SVOedhzPP7M

with the head off pipe some water in the head water inlet directly and see what comes out ..could be stuck water passages with impeller chips

try flushing the head backwards from the water outlet area (sorry I do not have pictures but surely you can at least flush/blow the water passages with just air pressure to see how good air circulates in the head water passages

take out the exhaust cover plate to inspect as much as possible if the head is the issue

Joining AOMCI has priviledges 🙂

[frankr]

Two possible gotcha’s come to mind.
1. Look at the water pump housing. See that hole drilled at an angle right below the rubber grommet? Is that hole clear? The purpose of that hole is to keep the cup around the drive shaft filled with water so the pump doesn’t suck air through the hole the shaft passes through.

2. Some of those motors had a restrictor up inside the water tube. It’s up in there a couple of inches. Those things get plugged up with debris.
Cure: Drill the hole out bigger.

2-1/2. I’ve done the spin it with a drill myself lots of times. But that isn’t a real good test. It doesn’t allow for the fact that while the engine is running, the pump is surrounded by air (actually exhaust). Any of that air/exhaust leaking into the pump will affect the way it works (or not).

[garry-in-michigan]

There were a couple of changes made in the powerhead to exhaust housing gaskets to acomedate slight changes to the cooling water flow. Be SURE the gasket used is the proper one for that model.
The model number tag may have been remove because it was a replacement from a different year, This could mean there is no proper gasket. . . . 😕

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