Porosicity in block casting???

mox-ct · Newbie Joined: 29 Apr 2010 Posts: 3 202.78 points

My engine builder finally finished my 454 and had it on the dyno for breakin and testing. After breakin the oil filter was pulled and he found foam.

Pulled the valve covers looked for water leaks, none.
Pulled oil pan and found a drip.
Pulled the intake nothing wrong there.

Found a leak between the lifters for number 6 and 8 cylinders. The leak is located where the camshaft is at the bottom of one of the water jackets between cylinder and lifters.

It doesn't appear to be a crack, but maybe a casting flaw.

Going to start over with another block. Damn!!!

clay · Posted: Fri Apr 30, 2010 11:53 am Post subject:

Ouch! That stinks. Hate to hear that. Clay

Big Dave · Posted: Fri Apr 30, 2010 12:14 pm Post subject:

If it is a used block, odds are it is not a porosicity issue but a crack caused by over heating the block.

I now only use Dart Big 'M' blocks or GMPP "Bow Tie" blocks when building new motors from now on as I have learned it is actually cheaper than remachining a used block of questionable heritage. (I did reuse a '509 SBC I had because I had put 270,000 miles on the block and knew it's history). If you are lookiing for a replacement block I highly recommend trying the Dart block over another used piece.

Big Dave

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1149 536969.38 points

I had the exact same thing in a 71 454 vette. It was completely done and in the car, dialed in and all restored and couldnt figure out why it always had a little condensation on the oil cap that was milky. I figured eventually the problem would surface and one day it started knocking faintly. I pulled the pan with it still in the car and couldnt see any problems at all with the bearings and no leaks (coolant) I needed it off my lift the next day and decided to put the bearing caps back on. When I got to #4 I noticed one little green drop forming on the crank journal but hadnt dripped on the floor yet. I looked up and the #4 main bearing saddle part of the block was cracked all the way around, and up through the cam tunnel and into the valley a little bit ironically between 6 and 8. That is the first time I have seen one crack there, but it was visible to the naked eye once I knew where to look. I had another block machined and transferred all the parts. What a pain. Good luck with yours. Oh and Big Dave, we even had a Dart block that was new all finished and assembled on the dyno, and we filled the oil pan up with water through one of the lifter bores from massive core shift. Nothing is a guarantee I guess