1971 johnson water pipe

[phoenixe1123]

Hey there,
I recently inherited a boat motor that I've been working on, Its a 1971 100hp johnson outboard. Once I got the engine running I found that one bank of cylinders was overheating after digging into the engine and dropping the lower unit I found what I think is the problem. It looks like the previous owner had an issue with the water pipe in the intermediate unit? in the picture below, it looks like the water pipe was sleeved with a steel or aluminum pipe, the pipes are not produced anymore but I was wondering if I could find one how would I go about replacing it? I have a Seloc manual but haven't been able to find any information on the removal or replacement of the water pipe. any information would be greatly appreciated.

 

[F_R]

Can't really tell from here, but it sort of looks like a pretty decent repair. Are you sure that is the problem?

Anyhow, the water tube is attached to the bottom of the powerhead adapter. Not a simple repair. Powerhead has to come off, then the rest of the motor removed from the motor mounts, then finally you can remove the powerhead adapter.

 

[phoenixe1123]

Well as it turns out I wasn't aware that there was supposed to be two short plastic pipes used for guides and that's one of them. This is the first outboard I've attempted a repair on. since that isn't my issue I had a couple of questions I was hoping I could find answers to.

--There's a black box between the cylinder banks that im guessing houses the thermostat or is it located in the cylinder head?
--Are parts still available for the cooling system on an engine this old?
-- Could a failed thermostat cause overheating in one bank?
--Does the cylinder head have to be removed to check water passages in the block/head or can it be checked by removing just the cylinder cover?

Any help is appreciated

 

[F_R]

1. Yes.
2. Yes
3. Not likely. But I learned never to say never. On the other hand, when they fail, 90% of the time they fail "open"
4...I don't know where the blockage is--IF it is blocked Again, unlikely. Those passages are big
5. Where are you running this thing?

 

[phoenixe1123]

I'm running it in a 55 gallon drum about 3/4 of the way filled. it was running about 15-20 mins while I attempted to dial in the low-speed screws on the carburetor.

 

[racerone]

One water pipe feeds water to the engine.----The other is a return line I believe.-------So the overheat on one side is not related to one pipe being damaged.-----Next step is a compression test as a blown head gasket causes overheating.