Where are the 2 engine block COOLANT drain plugs at.......

[73rivi]

on my 73 Riviera?

Thanks in advance,

Jared

[Lapham3]

Jared-There may not be any. Somewhere in the early 70's they were eliminated. I've drilled/tapped before as the round boss is still there around the middle of the block just up from the pan rail-good luck

[NTX5467]

It might be a really messy and "wet" way to do it, but removing the core plugs is a much better way to get the accumulation out of the water jackets back there. The "accumulation" includes sediment from the entire cooling system, which tends to settle out in the lowest part of the system (i.e., the rear cylinders of the water jacket). You might get the coolant out with the side-of-the-block drain holes, but you (most probably) will not get all of the accumulation "stuff" that's rearward of them. It's that rear-of-the-water jacket accumulation that can lead to centralized overheating and slight detonation under load . . . when EVERYTHING's set to specs.

Another thing is that the crossflow radiators can look good from the top (i.e., looking down from where the radiator cap screws on), but can be plugged up down where you can't see. Using an infrared non-contact temperature gauge

"gun" can indicate where the radiator's hot and not as hot as it should be (i.e., plugged up or restricted) without taking anything apart.

Just some thoughts . . .

NTX5467