johnson 3 up 1968 JHF 23m water circulation

The motors not circulating water. I’ve taken the lower unit apart and looked at the impeller it seems fine I did an impeller test of the lower unit with an electric drill and it pumps water at the lower unit site. I’ve cleaned out the tube up the shaft to the head. For the life of me I can’t find the P hole on this thing, there is a hole On the bottom aft end of the cowling which I suspect is the exit hole for the water but nothings coming out. It’s a collapsible shaft so I’ve used an air compressor both directions from the middle of the shaft to the impeller and from the middle of the shaft up to the head.
I guess two main questions one where is the P whole and two why isn’t it passing water. It didn’t look terribly gummed up with guck so I don’t think the head is all gummed up. The motor itself runs like a charm. Hope somebody out there can you give me some ideas thanks Hope somebody out there can you give me some ideas thanks.

In a bucket the water must be 6 / 8" ABOVE the impeller.-------Water mists / sprays out with exhaust on the holes on the back of the exhaust housing.

Thanks for the message. The tank level is right up a good 8 inches. So are you saying there is no telltale “P hole”at all the back of the cowling for the exit of cooling water?it is exhausted through the exhaust manifold?
There are eight small holes on the back of the shaft which I assume is what you referred to as exhaust manifold. There is some water coming out of there but not a lot so is that the only cooling the motors getting?

It is called an " exhaust housing "-----Water mists / sprays out those holes.------Most ( 94.5 % ) of the cooling water goes out the bottom with the exhaust where you can not see it.-----Time to read some manuals or ask your friendly dealer to explain this to you.

Learned a lot to day, learning more everyday. Thanks for your input.