I need to drain a 4.8 block of all the anti freeze.......(this is not my vehicle and I've not worked on a 4.8 before so this is the reason for my question)...... I see 2 drain plugs in the vicinity of the oil filter .....which one is the drain plug...... the plug above looks like it is 3/4...... the one closest to the oil filter looks like it is between a 1/4 and 3/8....... which is it and how to you get them off and do both of them need to be removed or only 1 to drain the block?

https://charm.li/Chevrolet/2003/K%20....8L%20VIN%20V/

How empty does it need to be?

What year, make, and model is this 4.8 in?

I believe the coolant drain plugs are Allen or possibly Torx.

Can you post pictures of what you're looking at?

I'm replacing the head gaskets on a 2003 Silverado 4.8. (I've never worked on a vehicle like this, and it'* my spouses boss'* vehicle so I want to make sure I do it right).

Okay then you don't need to worry about draining the block through block drain plugs. They have the potential to create much larger issues it they are corroded and/or stuck and/or etc. Just drain it at the radiator.

Have you replaced head gaskets on anything before?

4.8'* survive severe beatings with little complaint. Are you sure that it needs head gaskets?

Oh, i should have also told you ( I had just gotten home from a long day of work and didn't think about it)....... it also had a valve job done at a a machine shop because a few of the valves were leaking so the heads had to be pulled. I drained the radiator, and then saw some additional coolant down in the bolt holes, and the other engines I've worked on before had drain plugs that were easy to work with and this one did no seem to be easy to deal with, and I wanted to make sure all the water was out of the bolt holes, as I have always done it that way before.

A little compressed air will get that little bit of coolant out of the bolt holes. Use a rag to keep it from spraying back all over you.

Who did this valve job?

Did something get messed up during reassembly?

How many miles on this truck?

Are there any major modifications to it, especially the drive train?

The heads were taken to a local machine shop to do that job, the vehicle has 190k on it and the engine was misfiring..... we found several of the intake valves leaking (found by doing a wet/dry compression test and a leak down test) so we pulled the heads and took them into a machine shop to do the valve job and make sure the surfaces were flat.

I see. So now you're putting the heads back in?

I've never had trouble like this before getting bolt holes dry etc...... So since I'd never done this on GM 4.8, it was just wondering if there was a way to do it that I was missing as I didn't want to put it back together with any moisture in the bolt holes whatsoever.