Half Drained SBC Block Cracking
December 10th, 2018, 7:46 PM
#1
CF Beginner
Thread Starter
Join Date: Dec 2018
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Half Drained SBC Block Cracking: Pic of engine included
Has anyone ever heard of a half drained SBC block or aluminum head cracking over night? Was replacing freeze plug behind the starter and wasn't able to finish. Left half the block half drained over night (did not drain complete cooling system), temp in Northern NM dropped to about 16 degrees during the night. Next morning after completing job, saw leaking coolant from stainless steel flexible exhaust pipe once engine was started after replacing bad freeze plug.
Little more background info. It is a rebuilt 327cu inch 350 HP, was a home rebuild. Running edelbrock e-street heads and air gap intake, HEI Distrib, hooker headers, holley carb. Only used 50/50 mix of store bought Prestone during time of engine install.
1st weekend of engine install. Got engine in, started right up, broke in new cam shaft at 2500 RPM for 15 Min. Open header, no thermostat, no transmission or no transfer case. Engine seemed to reach normal operating temp while break in, no serious leaking from exhaust or anywhere else. Things seems to be GREAT.........
2nd Weekend of install. Put transmission and t-case back truck. Took for about a 5 mile round trip got back home found a oil leak from oil filter adapter and a coolant leak from that pesky freeze plug. Cool, no biggie right? Mid week took ride to gas station to put gas, this time about a 12 mile round trip still no catastrophic leaking other than these two leaks mentioned above. Engine at normal operating temp both 5 and 12 mile rides.
3rd weekend this Sat. Fixed oil filter adapter leak ( missing oil filter adapter gasket), modified exhaust pipe on passenger side due to different headers as previously using, so cut and installed stainless steel flexible exhaust pipe to get around the tight fit in the transfer case and front drive shaft area. Started truck to check modified exhaust pipe for leaks, no exhaust leaks. NOT leaking coolant through stainless steel flexible exhaust pipe. Late afternoon decided to drain block on passenger side to start working on getting the freeze plug replaced. Removed starter, drained half the block from coolant plug on passenger side located by oil pan. Got freeze plug punched in to engine, got tired of wrestling with getting the plug out, lost day light and was cold from being outside all day and figured my best bet would continue in the morning....
Yesterday morning, got plug out within half hour, put new one in little hassle. Filled back with coolant few hours later to let sealant on freeze plug cure. Started the engine, got under truck for leak check and noticed coolant leaking through stainless steel flexible exhaust pipe I modified the exhaust pipe on. Convinced myself it was strange but not a big issue, got back into truck to go for ride. Immediately getting onto highway was smoking from passenger side tail pipe. About a mile down the road seemed to clear up, kept on for about a 10 mile round trip, truck ran pretty good. got home and was smoking immediately shut off the truck and had oil pouring out the back side of the engine. swiped some leaking oil with my finger and looked kind of milky. Checked dip stick and pretty freaking bad, knew it was not good. Realizing how bad the situation is didn't really care to look further into where the engine was leaking the mixed oil/ coolant from and here I am writing.
Think the engine block or aluminum head cracked over night? Where should I start investigating the problem?? Please keep comments positive as I have busted my butt last four months pulling out, rebuilding, cleaning and painting parts and yes spending money. I will answer any additional questions. Thanks..........
Little more background info. It is a rebuilt 327cu inch 350 HP, was a home rebuild. Running edelbrock e-street heads and air gap intake, HEI Distrib, hooker headers, holley carb. Only used 50/50 mix of store bought Prestone during time of engine install.
1st weekend of engine install. Got engine in, started right up, broke in new cam shaft at 2500 RPM for 15 Min. Open header, no thermostat, no transmission or no transfer case. Engine seemed to reach normal operating temp while break in, no serious leaking from exhaust or anywhere else. Things seems to be GREAT.........
2nd Weekend of install. Put transmission and t-case back truck. Took for about a 5 mile round trip got back home found a oil leak from oil filter adapter and a coolant leak from that pesky freeze plug. Cool, no biggie right? Mid week took ride to gas station to put gas, this time about a 12 mile round trip still no catastrophic leaking other than these two leaks mentioned above. Engine at normal operating temp both 5 and 12 mile rides.
3rd weekend this Sat. Fixed oil filter adapter leak ( missing oil filter adapter gasket), modified exhaust pipe on passenger side due to different headers as previously using, so cut and installed stainless steel flexible exhaust pipe to get around the tight fit in the transfer case and front drive shaft area. Started truck to check modified exhaust pipe for leaks, no exhaust leaks. NOT leaking coolant through stainless steel flexible exhaust pipe. Late afternoon decided to drain block on passenger side to start working on getting the freeze plug replaced. Removed starter, drained half the block from coolant plug on passenger side located by oil pan. Got freeze plug punched in to engine, got tired of wrestling with getting the plug out, lost day light and was cold from being outside all day and figured my best bet would continue in the morning....
Yesterday morning, got plug out within half hour, put new one in little hassle. Filled back with coolant few hours later to let sealant on freeze plug cure. Started the engine, got under truck for leak check and noticed coolant leaking through stainless steel flexible exhaust pipe I modified the exhaust pipe on. Convinced myself it was strange but not a big issue, got back into truck to go for ride. Immediately getting onto highway was smoking from passenger side tail pipe. About a mile down the road seemed to clear up, kept on for about a 10 mile round trip, truck ran pretty good. got home and was smoking immediately shut off the truck and had oil pouring out the back side of the engine. swiped some leaking oil with my finger and looked kind of milky. Checked dip stick and pretty freaking bad, knew it was not good. Realizing how bad the situation is didn't really care to look further into where the engine was leaking the mixed oil/ coolant from and here I am writing.
Think the engine block or aluminum head cracked over night? Where should I start investigating the problem?? Please keep comments positive as I have busted my butt last four months pulling out, rebuilding, cleaning and painting parts and yes spending money. I will answer any additional questions. Thanks..........
Last edited by donalda00; December 10th, 2018 at 8:34 PM. Reason: Need more views
December 11th, 2018, 4:37 PM
#5
CF Active Member
Join Date: Feb 2018
Location: Currently the Candian Gander is wintering over in New York.
Posts: 185
Likes: 0
Received 1 Like
on
1 Post
This is the sort of thing that makes me cringe. It's about as bad as having to replace a heater core.
I noticed that when you built the engine, you went back with:
"Only used 50/50 mix of store bought Prestone during time of engine install".
that would have been in the partially drained block, left overnight.
I don't think your problem is a crack, unless you count installing a head gasket upside down or backwards, or the bolts weren't torqued tight enough and the repair failed prematurely. Maybe the block was missing the dowels, so the head is off-center
When you were preparing the short block to install the heads, did you run a blind tap to the base of the head bolt mounting holes to verify that the threads weren't going to bind the bolts? If the holes had trash in them, the bolt will bind and give a false torque.
If it were me, I would pull the valve covers and try to re-torque the heads in case one or more of the bolts was missed or is loose otherwise. That might save you from having to pull the motor apart.
On the subject, anytime I would try this option, I would have the engine cold, with the radiator cap off, so no water jacket pressure. Take each bolt and first loosen, and then tighten to full torque. This assumes all of the head bolts are already at proper torque. With this procedure, you are attempting to verify uniform tension to seal gaps at the head gasket. What is important is that you not try to tighten any bolt unless you loosen it first.
Keep us posted . . .
I noticed that when you built the engine, you went back with:
"Only used 50/50 mix of store bought Prestone during time of engine install".
that would have been in the partially drained block, left overnight.
I don't think your problem is a crack, unless you count installing a head gasket upside down or backwards, or the bolts weren't torqued tight enough and the repair failed prematurely. Maybe the block was missing the dowels, so the head is off-center
When you were preparing the short block to install the heads, did you run a blind tap to the base of the head bolt mounting holes to verify that the threads weren't going to bind the bolts? If the holes had trash in them, the bolt will bind and give a false torque.
If it were me, I would pull the valve covers and try to re-torque the heads in case one or more of the bolts was missed or is loose otherwise. That might save you from having to pull the motor apart.
On the subject, anytime I would try this option, I would have the engine cold, with the radiator cap off, so no water jacket pressure. Take each bolt and first loosen, and then tighten to full torque. This assumes all of the head bolts are already at proper torque. With this procedure, you are attempting to verify uniform tension to seal gaps at the head gasket. What is important is that you not try to tighten any bolt unless you loosen it first.
Keep us posted . . .
Last edited by Kazoocruiser; December 11th, 2018 at 5:04 PM.
December 11th, 2018, 5:53 PM
#6
CF Beginner
Thread Starter
Join Date: Dec 2018
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
I made sure to tap all head bolt holes to clean out old bolt sealant. New ARPhead bolts with head bolt sealant with teflon. Made sure the block deck was extra clean, sanded dowels clean so heads slipped on nice and easy to them. I used the copper spray on the head gaskets maybe I put that upside down after spraying it. I am hoping it's a matter of redoing the head gasket on the passenger side and intake gaskets....I only have time on the weekends to work on it and it being holiday season let's see when I get around to it. How would you suggest best way to flush block from contaminated oil? Sea foam?
December 15th, 2018, 12:09 PM
#7
CF Active Member
Join Date: Feb 2018
Location: Currently the Candian Gander is wintering over in New York.
Posts: 185
Likes: 0
Received 1 Like
on
1 Post
The only suggestion I would make is not using any kind of spray-a gasket anything on the head gaskets.
That and doing a 10 minute run-in with fresh oil, and then a new filter with new oil as a block flush.
And anytime I have done heads on anything, I have never used anything but engine oil to lubricate the threads.
My .02
That and doing a 10 minute run-in with fresh oil, and then a new filter with new oil as a block flush.
And anytime I have done heads on anything, I have never used anything but engine oil to lubricate the threads.
My .02