Water jacket drain plug question

[OldRedFord]

On my 460 block, on each side of the blockthere is a water jacket drain plug. Already repaired one, but the other...

I drilled it out fine, but it seems that the passage behind is blocked off from the water jacket?

I tried blowing compressed ai in through the hole, the air just shot right back out.

I tried looking down the water jacket from the deck surface, I can not see wjere i drilled the plug out.

I tried to shine a bright light in from the hole, can not see any light getting through.

What gives?



No the same block, but the plug at the back is in the same spot.

I did ask on the one 460 sie but did not really get a answer.

[70_F100]

Probably years of crud build-up. Sludge, scale, rust, etc.

That stuff can be really stubborn, and it's tough to get out. Compressed air won't do it.

Try digging into it with a screwdriver and see if you can loosen it up.

[JMcTurnan]

Soaking some gasoline in there? Maybe degreaser? Let it sit overnight, then try a screw driver.

[eggman918]

If it is rust and junk try a small amount of swimming pool acid in hole it will eat the crap but not the good/clean cast iron
Gloves and eye protection mandatory ,use acid let it work a bit then flush with water brake it up with a probe/screwdriver might take a couple of times
Good luck

[oldschoolrods]

my 360's were plugged up solid, took lots of digging out and a trip through the jet spray washer to get it all out. one thing i'm planning on doing is replacing the pipe plugs with radiator drain cocks so the antifreeze can be drained out of the block easier when it gets changed.

[eggman918]

drains help to stop that issue in the future if you use them, same principle as the one on a water heater
the junk cant build up as easily

[OldRedFord]

If it is rust and junk try a small amount of swimming pool acid in hole it will eat the crap but not the good/clean cast iron
Gloves and eye protection mandatory ,use acid let it work a bit then flush with water brake it up with a probe/screwdriver might take a couple of times
Good luck

Can you get swimming pool acid at a local hardware store or Lowes?

[eggman918]

Yes Lowes or a super market it comes in 1 gallon plastic jugs,It is not expencive

[BobbyFord]

I checked my 460 block and found the passage blocked, too. It was just rusty scale. After poking thru, I installed one of these:

[JMcTurnan]

Mine being a 351w boat motor was a bit scaily at the threads. But it was clear and let fluid out freely when I opened it.