160 oil cooler pipe make up

Hi, I have a little situation. Oil cooler pipes are leaking, as a bit of a faff I decided to do away with the cooler. Bought a 135 filter housing and went to fit it today. Cannot get 2 of the 4 x 8mm bolts undone. One has snapped and one I’ve decided not to try any more as I thing that will snap. 
As a result I want to make a simple loop of flexible hydraulic hose as a bypass. Anyone know the union size/type? I’ll probably fix it to the bulkhead . 
if anyone has any good ideas they’d be welcome.
Thanks