: Blocks, cracks and heat



89falcon
12-07-11, 05:08 PM
I've got a question for the big brains here.

Seems that a fair number of high mileage blocks crack after the have been timeserted, inserted or studded....and in a lot of cases these blocks, by the very nature of headgasket failure, have gotten "hot" on a couple of occasions.

Do the blocks lose some strength from overheating? Since Aluminum is prone to fatigue cracks....much more than steel or cast iron, is it possible to heat a "good" used block up to a reasonable temp and cool it the "right way" (whatever the "right way" is...) so that it get's strength back?

I'm not a "mech eng" so help me out here!

Ranger
12-07-11, 09:15 PM
The cracked blocks I have heard of were cracked before they where inserted or studded. I have never heard of heating a block to get strength back. I don't think it looses any in the first place.

ThumperPup
12-07-11, 09:58 PM
Mine was cracked or damaged sometime between the first HG Job and just took a few months to be noticeable or it cracked after
how it would crack after i have no idea
eithere that or
the Tech didn't inspect it fully and it was bad before so 3 potability for me on it

i would really hate to think that it was already damaged and the tech just overlooked it that would really be bad

maeng9981
12-07-11, 10:23 PM
I heard that those cracks are usually caused by uneven torque applied to each head bolts due to some of the failed bolts not holding as it should, but I never encountered a cracked block nor failed bolts so don't know from experience.

Ranger
12-07-11, 10:27 PM
I know Joe at Midwest Cadillac Repair has found several before he started working on them. I think he inspects them now before tear down.

ThumperPup
12-07-11, 11:08 PM
I know Joe at Midwest Cadillac Repair has found several before he started working on them. I think he inspects them now before tear down.

i hope he inspected mine it be a real sad story if he didn't
but i don;t know i just know cant cry over spilled milt and its been over a year
i just know im still upset about the crack and dont get how the heck it could crack after the HG issue but its possible

Ranger
12-08-11, 10:49 AM
Yours was done BEFORE he started finding the cracked blocks. He most likely never knew it was cracked.

ThumperPup
12-08-11, 10:31 PM
yeah that is what i keep telling myself
just wish that they knew about the cracks before mine was done that way at least they could have looked for them
another thing is i thought he was going to be inspecting the block and everything to make sure they where good before putting it back together

i know he had the entire half case apart and all cause he broke the bolts on the Oil pan and had to take it apart to get to those so not sure it would have been much harder to double check the block but oh well
spilt milk is spilt milk

johnny kannapo
12-12-11, 06:02 PM
I believe from what I see, most cracks are stress related and found around mounting areas & not temp related.

vincentm
12-14-11, 11:35 AM
My crack is behind the front exhaust manifold.

ThumperPup
12-14-11, 03:30 PM
My Crack was all the way across the Front Bank Head bolts i guess you could say

the crack ran along the block from 2-4-6-8