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Need help with supposed cracked block on a 96 ss

5K views 55 replies 8 participants last post by  96texasss 
#1 ·
Picked up a 1996 impala ss yesterday that supposedly has a cracked block. I need some help to determine if it is really cracked or if it may be something else. The previous owner told me he had top end rebuilt and the motor has lots of new parts including opti and water pump. It cranks and runs the idiot light is flashing says low coolant and runs real rough but it doesn't smoke just really need some guidance or a good idea of what to start checking. I have another 5.7 that I pulled out of a 95 and before swapping them I want to see if it's salvageable or not. Any help would be greatly appreciated


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#2 ·
Picked up a 1996 impala ss yesterday that supposedly has a cracked block.

.....I need some help to determine if it is really cracked or if it may be something else.

......It cranks and runs the idiot light is flashing says low coolant and runs real rough but it doesn't smoke just really need some guidance or a good idea of what to start checking. .....
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Considering just the useful info, there's a lot left for you to contribute before a worthwhile response.

You surely asked, so what indications exactly did the seller give for her/m to state the block was cracked? Especially since it runs.
If internal, how does/did her/m know it's a crack and not mech. failure? If external, are/was there physical symptoms of a crack - leaking or shooting fluids, staining, visible break?

You may want to fill the AF, find a way to pull codes, and deal with the rough condition. Do you or a friend know how to tell a flattened cam, broke rocker, rod knock or any number of things potentially caused simply by seller's abuse?

That's all I got until you dig more on your own. It's gotta be better use of time and $$ to buy and study a FSM for $50 before swapping a whole motor.
 
#3 ·
The guy told me that he had taken it to a shop and that they told him the block was cracked. I was thinking a leak down and then a compression test to see if there is any noticeable difference in the cylinders and or a loss of pressure in the cooling system. I had it on a trailer and when I pulled her off I didn't see any indications of a leak so I was thinking that unless the Crack is internal or so miniscule that it doesn't leak that it could be something different because it runs rough but it runs cranked right up no problems and for 1700 it was a steal so I'm not sure as to what to do or where to begin

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#6 · (Edited)
The guy told me that he had taken it to a shop and that they told him the block was cracked. ....

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Ok, you know pretty much nothing at this point. It could be anywhere from simple ignorance, incompetence or laziness, up to hopeful charge for teardown/replacement.

And at 3 posts total under your belt you may not realize the perhaps best feature about this forum is the vast intel archived here. My guidance is fill the AF. It might take 5 start cycles for the light to go off - don't worry. Just get all the damn air out of the system. There's search for that. Get to AZ/O'R or Advance to read codes and deal with those first. There's search for every code you can think of. Then, attend to the thousand normal maint. and upkeep expected for a 20-year old car. Hoses, wires, plugs, sensors, grounds, fuel system, filters. There's search for all that. And learn all the acronyms that can cause headaches, IAC, FPR, TPS, ECT, EGR, ICM, IC, EVAP. Yep, there's search for those as well. Along with all that, there's numerous stickies on 'rough idle/running'. Search them all.

EDIT: Your last above noted. But all insight still holds. 1,700 not bad. I'd still establish what's really the issue before swapping the motor - even if free. You'd hate to do that if it was only a giant overheating that fried a hose/wire/component causing rough running.
 
#4 ·
Fill it up with distilled water and pressure test system.

Coolant low, no signs of leak on trailer, runs like poo...

Leans towards it dumped coolant/overheated and may now have other issues.
Guy sold it because he didn't want to deal with it, now it's your turn

Just my .02
 
#8 ·
OP

any "2nd opinion" from any of us based on what you post (somewhat second hand info from PO) would be just a "guess"

As noted most auto part stores have OBD 2 code reader they loan out. You can buy them for $20 or so at places like Harbor Freight

Cracked block....not very common but sounds like PO got in over his head on mods, may have driven the motor to hard or it over heated severely which can cause head or block damage

Do a cooling system leak test (you usually can get that as a loan a tool thing) also and scan for codes and google wtf those codes mean and focus on whatever those pretain to.

go buy a $1 jug, or two, of distilled water for the coolant pressure test. No need spending $ on coolant until you FIO if coolant system, heads or block is leaking water somewhere
 
#26 ·
what specific misfire code did it show? 0300 or 030x. The later (x=1-8) would indicate the specific cyl.

"oil looks a little milky..", like saying a little pregnant....so if the oil is milky you either have blown head gasket or cracked head....or block......or radiator oil cooler has a internal leak into the cooling passage

you need to find the "why" the oil is milky but if PO said it has a cracked block and you have milky oil...ouch
 
#11 ·
Before starting it again I'd just change the oil for my own benchmarking. Go over the ex. manifolds with a fine-toothed comb for cracks, broke manifold bolts, - anything you think might have been injured from getting real hot. I hear the more elaborate readers and especially scanners at shops can read conditions per cylinder.

What does search show for your particular misfire code?
 
#12 ·
Pull each plug, and look at it for color. If one is different from the others, note the difference, and the cylinder. Depending on what the difference is, that could be the cylinder that is misfiring. Driver's side is 1,3,5,7, and the passenger's side is 2,4,6,8. Let us know what you find.
 
#14 ·
I'm pull the plugs this morning and do a leak down and check the plug wire sequence. The po had the egr just hanging and plugged in but without the vacuum lines that helped a little and I'm missing an exhaust manifold bolt I will post some pics after my cup of coffee

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#15 ·
Hahaha No Hurry - Enjoy Your Coffee

We've ALL seen pics of broke man. bolts. lol And broke rotted collapsed hoses. And untold instances of disconnected/missing sensors and parts.

Depending on how long running with that broke bolt combined with whatever stress the motor's been through, the O2 sensors may have become "weak" even without throwing a code - causing any number of operating maladies.
 
#17 · (Edited)
OK Now We Need That Pic

EDIT - OK, caught your pics below. HELPS aisle at AZ should put you straight with a stud. Gasket is kinda shiny and with the missing stud begs the question why the past owner (or his mechanic) was messing with it. New cat? If the asbestos gasket is blown out anywhere then the same lean readings causing issues.
 
#28 ·
@ this point I wouldn't worry about how it runs or any codes.
As stated previously fill it up and pressure test it.
A compression test is also recommended.

I wouldn't try to get it running right, change oil, or replace any parts until you know what problems are. Might just be wasted $/time.
 
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