Quote Originally Posted by fesm_ndt View Post
yep seems everyone who has done it thinks its great. I was thinking of buying a heavy duty radiator from the UK but I am worried this bypass hole would still be in it, so I will try to get a 5 core made in KL.

I read somewhere that the hole, which I also think daft is there to help get air out of the lower tank as the inlet and out let are on the same side (also daft). However given the good reports I think I will just take a little extra time filling and plug the hole (Pinzgauers take forever to fill as there can be loads of air pockets in the system, its just a matter of paitience).
Dual pass rads have been around forever, all the race cars I ran/worked on used them, we just had small bleeds at the top of the bottom section of the header tank to make sure they were bled.

All L/R would need was a 1/16" hole, but I'm guessing they were concerned they would block up.

The other alternative is a spigot and return back to the main header/fill bottle as the t/stat housing and top of the radiator do.