4.3L intake manifold drain?

[nola mike]

I've seen discussion about an intake manifold drain that needs to be pulled to winterize the 4.3L vortec. I don't see a super obvious drain plug on mine, and can't find anything in the manual about it. Could someone point me in the right direction? Pic is of my intake manifold, the only thing that looks like a potential drain point to me is circled...

 

[Lou C]

that is it.

 

[nola mike]

So, went to winterize today (so final compared with the 3.7l!). Wow, glad I removed the petcocks and probed the drains on the block. Not sure the purpose of those except to help sell short blocks in the spring. All took me 30-40 min, could do it easily in half that next time I think.
But I removed that plug in the manifold and got nothing out. I'm not sure how any water would get trapped in there after pulling the t stat hose and manifold drains. Not a huge deal to do, but can anyone confirm that this is necessary? Again, not mentioned in any of the 4.3 manuals that I've seen.

 

[Lou C]

I have wondered about that too and the only thing I've see was a service bulletin from OMC that said that some 4.3 Vortec manifolds had cracked, so they felt it was necessary to drain that area. I have the pre-vortec and the manifold just drains when you drain the block drains and remove the bottom end of the big hose between the stat housing and the circulating pump. Maybe if the boat is stored at a certain angle that part of it doesn't drain? They must have changed something in the casting that causes it to hold water some how....
If you look at the bottom side of the manifolds, the castings are definitely different, the water passage for the pre-vortecs was just between the 2 front water ports to each cyl head and then there is an exhaust crossover in the center that is covered by a tin cover (I guess to keep the oil from getting overheated by the exhaust cross over. The Vortec design looks totally different on the bottom, you can't really tell where the water passage starts and ends....

 

[Rick Stephens]

Once you pull the water pump hose and the block drains, should be set. I don't have a drain there either.

 

[Lou C]

I guess you could just pull it to be on the safe side.

 

[nola mike]

I guess you could just pull it to be on the safe side.

That's what I did, but nothing came out = no need to pull it. Looks like this weekend so far is shaping up to be around 70', sunny, no wind. So I may yet dewinterize and rewinterize. Missing the 470!

 

[Lou C]

My next one will have closed cooling for sure. At least a half system + remote oil filter. Two must haves for I/Os