Perkins 4108 / 4.108 - Hot Water Tank - Pick-up and return?

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Trying to help a friend out with some Gremlins and want to rule out the hot water tank.

Can anyone confirm if the correct pick-up is in the pic below? The pickup is the copper vertical copper pipe just infront to the right of the expansion tank cap in the pic below.

This engine configuration is the expansion / header tank aft (as you can see in pic), the head exchanger to to the stern (above the gearbox), exhaust manifold to the port and oil cooler to the port.

The return Y's into a return pipe AFTER the heat exchanger and straight back into the header tank (the inlet on the header tank is at the bottom of the header tank under the Perkins label above, essentially the most forward part of the engine, above the water pump / alternator (about half way between... sorry didn't think of taking a pic)

 

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Also, what metal is the header tank made of? I want to paint it tomorrow ... wondering what sort of primer to use.

Will need to be a suitable primer / paint to withstand the heat... many thanks.

 

[PlankWalker]

I'm only familiar with the low line version, but my calorifier take off and return are both at the front end of the cylinder head, one where you've got yours and the other right adjacent to it. Which is which I don't think it matters.