Block cracked. Pics. Don't let this happen to you!

ozanracing · Feb 22, 2007

The result of not throughly cleaning the threads with a chaser tap. Make sure you use a 7/16"-14 to clean the block every time you remove the heads! The buildup of rtv will give an inaccurate torque reading, and may strip the threads and/or crack the block like this:

Got a new block lined up with all the machine work done for $500.
Kinda sucks, but I'm looking forward to building up a new motor, already got the rings, bearings, gaksets etc... I might do a little write up of it from start to finish...
I just liked that block since I did all the machine work to it, too bad that I don't have access to the machines anymore so I have to leave up to the local engine shop...Got my engine stand from back home last weekend and there's a place that rents engine hoists for $30/day. So I'll keep updating.

troyGT03 · Feb 22, 2007

looks to me that you had a prob other than using a tap. looks like that area had become thin due to rust???

Daggar · Feb 22, 2007

troyGT03 said:
looks to me that you had a prob other than using a tap. looks like that area had become thin due to rust???

Ditto... Metal fatigue had a HUGE part in that thing breaking like it did.

vristang · Feb 22, 2007

Your getting a new block?
A little JBWeld will fix that right up !!!

I don't see any fracture surfaces in that top pic, just rust.
If you are just going to scrap the block, would you mind breaking that loose piece off and taking a couple of close up pics of the fracture surface?
It would be fun me to look at...

From what I see in the top pic though, corrosion was the major contributor to failure.

jason

EDIT:
Do I see a copper tube as a hood prop?

JChalfan · Feb 23, 2007

vristang said:
Y
EDIT:
Do I see a copper tube as a hood prop?

It could be worse.

I used to use a baseball bat as a prop rod in my '66. Then the cops took it.

Bastards.

Mustang78 · Feb 23, 2007

ouch, renting a pressure washer for a few hours wouldent be a bad idea either while the block's out...i did it to my project 82 the other day and it worked great, except the engine bay is gray on a black car..

~Mark~

ozanracing · Feb 23, 2007

Daggar said:
Ditto... Metal fatigue had a HUGE part in that thing breaking like it did.

The rust came after the crack. Here's the senario:
Everything's fine. After re-torquing the that head bolt I heard an audible "crack" sound. At the same time the bolt gave way a bit (but it's at torque). After driving I noticed a coolent leak drip from the bottom of the oil filter. I traced it back up to the bolt area. The gaskets were brand new but it appeared to be leaking from where the head meets the block. When started and run, the leak dissapeared. I thought it was because the heat made the metal expand, so the bolt wasnt clamping on down enough while cold. So I re-torqued it hot. It stripped. I pulled it and helicoiled it.
(if you remember from a previous post of mine where it stripped, I was going to use a timesert, but the helicoil was $15 and worked.) When it got past 50lbs on the torque wrench, It let go. More coolant came out. This whole time (3-4 days) coolant had been leaking in that spot. The last time it was started (just for a couple mins.) cooland was spraying out. That's the reason for the rust.

But I'm having fun with it, I am ready to pull the shortblock as of tonight.

I think I'll be cleaning and maybe painting the engine bay.
Also I may hide the remaining wires a bit (not like there's much left though)
Def. going to be cleaning threads every time now!

SMOKEDYA · Feb 23, 2007

Sounds to me that you got some kinda brains? doing your own machining, so why didnt you chase the threads to begin with peace

john

jikelly · Feb 23, 2007

Damn that sucks dude. I'd never seen a block crack like that. Makes me wonder how strong mine is.

ronburgundy · Feb 23, 2007

unfortunately this is the kind of stuff that happens to doityerselfers far more frequently than professionals. fortunately for you, you have a fairly reasonable fix as far as block and machine work go. price wise. i've seen worse stuff. good luck. i bet there were a few f bombs flying after you realized what happened.

86bluecobra · Feb 23, 2007

Yikes and i get chocked when i snap a bolt off in the block. Atleast i haven't had to get a new one yet.

greg251 · Feb 23, 2007

I see the spacers under the head bolts, you sure that bolt was not too long?. That will crack it every time. Ditch the RTV and use a good quality teflon sealer on the bolts. Also any junk under the dowel pins will cause problems as well.

stang&2Birds · Feb 23, 2007

Bummer!

I'm going to go out on a limb and say that MY guess is that water go into the cylinder and trying to compress the water is what made the block go bye-bye.

SOMETHING *HAS* to give when you have too much water leaking into the combustion chamber. Sometimes, it's (one or more):
o the block
o piston
o connecting rod
o valve
o valve stem
o push rod
o rocker arm
o rocker arm hold down bolt
o crank
o main bearing cap
o head (main body)
o head gasket
o head bolt
o spark plug
o spark plug threads

I think I got most of them. But, chances are your coil is still good! Phew!!

Bummer about the block. Like I say, I *try* to tell people the *right* thing to do and not feed them BS.

Since you take good pictures, if you want to do a good rebuild write up, you can use MS Word to do the write up and the pictures. If it's GOOD, and I don't have any "comments" , if you want, I'll host it on my website.

BlooDReigN · Feb 23, 2007

Might also help to use studs next time around...

stang&2Birds · Feb 23, 2007

Looking at the pictures closer, he's my better guess:
1) You have aluminum heads.

2) You did the tap slight off from perpendicular.

3) The heads expanded faster than the block (Duh!).

4) Exhaust & compression gasses got into the coolant passages.

5) The head heated up even more, especially, at the end, because of the lack of coolant and cooling.

6) As the head expanded, the head bolt, which was at an angle, put additionally stress on the block.

7) It was the expanding aluminum head, with the head bolt at an *angle* on your iron block, that lead to the eventual failure of the block.

With the above said, WHAT'S THE PROBLEM? Go to Wal-mart, get some cooling system sealer, and you're good to go!

stang&2Birds · Feb 23, 2007

BlooDReigN said:
Might also help to use studs next time around...

IMHO, not in this case. Read above.

greg251 · Feb 23, 2007

He said he never tapped it so how did he tap it crooked?. The block cracked when he torqued the head bolt and things only got worse from there.

jb1dsl · Feb 23, 2007

The thing under the head bolts are the adapters for 7/16 head bolts not spacers for long bolts

stang&2Birds · Feb 23, 2007

greg251 said:
He said he never tapped it so how did he tap it crooked?. The block cracked when he torqued the head bolt and things only got worse from there.

Sigh. Learn how a heli-coil is done.
Heli-Coil Install. Olds Quad 4 head example.
http://www.veryuseful.com/GM/tech/heliCoilInstall/

I wasted enough time last on the prev thread. So, have fun everyone! I have better things to do.

modusmortis · Feb 23, 2007

just went out and purchased a thread chaser today!

Just wanting to let you know that your block's sacrifice was not in vain!

Block cracked. Pics. Don't let this happen to you!

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