I am going through the hassle of converting a 4G63 VR4 to run RWD and I think I nearly have the rear water outlet sorted but with one small issue. For those who don't know when in the Vr4 the engine has the thermostat housing on the back of the block, it has to be eliminated for firewall clearance in RWD applications.
I had 3bolt flange water cut and had planned to weld on a piece of alloy pipe with a right angle join it wouldn't have been the best for flow. I then came across a 180B thermostat elbow that fitted up to 3 of the 2 bolts and has a low profile, I will need to get another flange cutted larger and use it as an adaptor, see blow.
My concern is that with the elbow pointing downwards and a larg section of the begining of the elbow being above the outlet on the block I might have issues with air locks at the top of the elbow. I started thinking of getting rid of the 3rd lower bolt into the block and came up with this, still slight chance of air lock but much better. I also have concerns that by eliminating the lower bolt and poor placement of the two top bolts the adaptor plate won't seat right. I have also considered countersinking the lower bolt into the adaptor plate and sealing it then have the elbow over the top of it but that might be an issue on it's own.
Do you think the first option will be ok? the elbow will run to an expansion tank that will be much higher up it might just be a matter of getting the air out then it should be good.
Factory flange pattern