: Now what do I do? Northstar block casting porosity



83CADMAN
06-19-13, 02:46 PM
I finally got all the holes tapped for STUDS but the last hole developed quite a pit / void about halfway down. Damn it’s a good size pit!
All the holes had looked real good after drilling through.
Question:
Is there anything I can do?
Does this kill my project?

stoveguyy
06-19-13, 04:50 PM
Hole "opened" up ? So how did it tap? It has full threads, top to bottom? Or partial threads?

83CADMAN
06-19-13, 06:16 PM
The hole tapped sweet as you please all the way to bottom. Its when I looked down the hole did things go difficult. (see photo)118266

Submariner409
06-19-13, 08:11 PM
94 Northstar ??? Have you read the sticky thread in Northstar Performance on "Root cause if head gasket failure ................." ? I think AJ's pictures of this fault are still in there.

You would be NOWHERE near the first to have uncovered yet another Northstar block casting porosity.

I'll leave it to AJxtcman, Tim Carroll, or Jake Wiebe to call this shot.

83CADMAN
06-19-13, 08:43 PM
94 Northstar ??? Have you read the sticky thread in Northstar Performance on "Root cause if head gasket failure ................." ? I think AJ's pictures of this fault are still in there.

You would be NOWHERE near the first to have uncovered yet another Northstar block casting porosity.

I'll leave it to AJxtcman, Tim Carroll, or Jake Wiebe to call this shot.
I'm not claiming that I'm the first one to discover the porosity ov the early N* engines.
I just want to know if I can fill the hole with something.
Any sugestions?

Ranger
06-19-13, 11:18 PM
Hate to say it, but I think you got yourself a boat anchor.

rodnok01
06-20-13, 12:06 AM
Gonna be a crap shoot if that is going to hold when you torque it down. That much damage and it'll probably not hold, sorry to say it's probably junk.

Manic Mechanic
06-20-13, 12:22 AM
Is the hole still sealed and air-tight? If so I would fill the void with Devcon, re-drill and tap, then continue on like nothing happened. As in I'd probably have no qualms putting the pedal down when necessary. We don't live in a perfect world. If there's no unseen further voiding behind those visible threads I would have no problem thinking the stud won't pull out with what you've got. The Aluminum Epoxy would just be insurance.

Vernon

vincentm
06-20-13, 12:23 AM
Block swap time

stoveguyy
06-20-13, 11:04 AM
U could torque studs and see if that stud holds? If so, than you may have no issues. The aluminum around the threaded is probably the thickest in block. That's where the load from headbolts is transferred into block. Now, how far is it from thread to water jacket void? Never sectioned a block before

Speedygman
06-20-13, 01:59 PM
If it was me I would use the modern epoxies, in my case I would use JB WELD. I would first make sure that I can screw the new stud in all the way with my fingers, flush out the hole with lots of brake clean or lacquer thinner then put a coating on the stud or use a small rod to put the epoxy down in the hole or void in the block then screw in the stud and let set for 24 hours and then unscrew the stud and if it doesn't screw back in with your fingers tap it again to clean up the threads. Just saying.

Manic Mechanic
06-20-13, 02:06 PM
Yep, must be something about Rotary Heads, I've had my share also. JB Weld is a great product but the Devcon is made specifically for Aluminum and filling voids in castings is one of the products specific applications. The expansion ratios have been matched etc.

http://www.devcon.com/prodfiles/pdfs/fam_tds_107.pdf

Vernon

83CADMAN
06-20-13, 02:07 PM
This is the only open casting void found in any of the holes. The depth of the void in the area of damaged threads is Shallow, nowhere near the cooling jacket and near the top of the oversized threaded portion of the stud. I did do an air pressure test and it proved tight.
118530118538


If it was me I would use the modern epoxies, in my case I would use JB WELD. I would first make sure that I can screw the new stud in all the way with my fingers, flush out the hole with lots of brake clean or lacquer thinner then put a coating on the stud or use a small rod to put the epoxy down in the hole or void in the block then screw in the stud and let set for 24 hours and then unscrew the stud and if it doesn't screw back in with your fingers tap it again to clean up the threads. Just saying.

I like your idea of aluminum epoxy fill, let set and re-tap.
Thanks for the optimism.

83CADMAN
06-29-13, 12:47 PM
The studs from CCC are installed, the heads are on and torque to 75ft#. It’s down hill from here now!
The casting void that opened up in one of the thread bores and the sheared guide pin were the only problems I’ve encountered so far. “Knock on wood”
The void in the block wasn’t all that big and I think there are enough good 5/8-11 threads to hold the stud. I checked out “Devcon” products and found it rather pricey so I used “JB Weld”, High temp / high strength epoxy. I used a popsicle stick as an applicator to fill the shallow pit then I re-tapped it and presto, no more corrosion promoting air filled void.
Since I hand reamed/tapped all the holes, the alignment of the studs were dead on. The gasket and heads slipped on effortlessly.
Thanks Tim for the studs! And to all to offered their optimistic words of advise I also thank.

P.S. Only time will tell if the little patch fails and I loose the HG seal. Then I might call it a boat anchor. Until then….

CadillacLuke24
06-29-13, 01:13 PM
Sounds good! I'd think if you followed the directions and got it nice and packed in there, you should be good to go! Can't wait to see the finished product :D

Submariner409
06-29-13, 04:06 PM
Here's a tip when working with threaded fasteners and various epoxies - either liquid or the various pastes thickened with silica, metal dust, or microballoons ............ If you want to refresh or create new threads using epoxy paste, go ahead and patch/partially fill your damaged hole. Thoroughly wax and wipe off the fastener threads and an inch or so of the shank - Simoniz seems to work best. Thread the fastener into the epoxied hole and let it cure. Once the epoxy has completely cured the fastener will unscrew out of the perfectly formed threads in the epoxy. Clean the fastener threads with lacquer thinner before using a thread locker.

83CADMAN
06-30-13, 07:01 PM
WHOOOHOOOO!
Its all back together and slung to the lift ready to go in…. but what’s this? 2 broken wires I discovered while de-greasing the engine compartment. Must have happened when I pulled the engine. The wires I refer to are quite small and connect to the “Vehicle Speed Sensor”, located on the A/T’s Final drive snout.
My question is:
Are the broken wires a resistant type that the entire length must be replaced or can I simply splice them back together and be good to go?

Ranger
06-30-13, 09:45 PM
I think they are just wires and you can splice them.

83CADMAN
06-30-13, 10:19 PM
That’s what I’m hoping Ranger. A little solder and some heat shrink.
I would be willing to guess those little buggers route thru the main harness to the PCM.

CadillacLuke24
07-02-13, 04:54 PM
Good work! Let's see her in all her glory when you're got everything back together!

rbb
07-04-13, 05:29 PM
I had a similar problem on my '05 engine swap, except I caught it before they snapped. Those wires run through the harness you may need to spend several hours trying to find any shorts caused by pinched wires and then using high-heat resistant electrical tape to repair the damage. Or spend $1327 on a new harness from www.newgmparts.com the short I had caused the ignition system fuse to blow whenever it drove a certain speed causing the car to stall while driving.