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coolant bypass hose routing

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#1 78zman



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Posted 30 October 2016 - 05:03 PM

thanks for viewing, im just about done with the rebuild on my 1978 280z and i dont quite know where the bypass hose on the cooling system is supposed to route to, there is a fitting on the thermostat housing but something just doesnt look right to me, all help is appreciated, i will supply pictures to best describe what im talking about and if anyone know how its supposed to be routed correctly please let me know. i own a factory service manual but looked in the entire cooling section but could not find a proper diagram or illustration. please let me know if i need to move this to the cooling section instead. thanks for reading.

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#2 NewZed


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Posted 30 October 2016 - 06:35 PM

It's not really a bypass hose.  Looks like somebody removed your air regulator and the heating plate that sits underneath it and just connected the tube ends.  The  AAR is shown on page EF-5, 7 and 17 and other places.  The proper hose routing is shown on EM-4.  Attached a picture.


I can't remember if that coolant flow helps avoid water pump cavitation or not.  There are discussions about it out there.  Replacing the AAR and plate would be a good idea, it's a convenient mechanism.  Could also be that everything's there but somebody couldn't get there fat fingers in to the tiny places to fix a leak so just bypassed it..  Anyway the coolant is supposed to flow underneath the AAR.

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#3 BluDestiny



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Posted 31 October 2016 - 05:04 AM

If you don't have the AAR, I would just do away with all those lines. If it's just not connected, I would hook it back up. 

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#4 Leskinen


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Posted 31 October 2016 - 06:41 AM

I don't have aar and I run the coolant bypass the same way you do. Works fine for me.
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