What would keep a new head gasket from sealing?

R

R18Civic

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This happened a couple years ago but it's always bothered me.

I pulled a head on my buick and found cracks between the valves so I replaced them. The head gasket didn't take on the front cylinder bank. I cleaned the bolt holes, used copper spray a gasket and took extra care to line up the dowel pins and gently place the heads on the gasket. Even torqued the head bolts to 37 lb ft plus 120 degrees.

After firing it up and test driving it I noticed a substantial loss in power. I pulled the front head and found a lot of coolant in cylinder number 5. The rear cylinder bank sealed right up without any issues.

What could of caused that to happen?
 
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What's the application? And why did you use the copper spray? IMO it isn't mean to be used on modern MLS head gaskets. It's meant for old flat head engines and copper gasket head gaskets.
 
Was the new head flat? Did you properly clean the block*? Did you clean the threads in the block*? Did your service manual suggest using that spray*? Does GM allow you to re-use the head bolts*?



*My quick search of Google on this topic suggests that you need to clean the block, chase the threads, use good gaskets (which means no spray ) and use NEW bolts.

Failure to follow those procedures will likely result in a gasket failure...and, of course, if the head itself isn't checked for flatness, that could cause it, too...
 
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Originally Posted by mattd
What's the application? And why did you use the copper spray? IMO it isn't mean to be used on modern MLS head gaskets. It's meant for old flat head engines and copper gasket head gaskets.


3800 V6. There were very fine scratches in the sealing surface and someone suggested the gasket spray.
 
Originally Posted by Astro14
Was the new head flat? Did you properly clean the block*? Did you clean the threads in the block*? Did your service manual suggest using that spray*? Does GM allow you to re-use the head bolts*?



*My quick search of Google on this topic suggests that you need to clean the block, chase the threads, use good gaskets (which means no spray ) and use NEW bolts.

Failure to follow those procedures will likely result in a gasket failure...and, of course, if the head itself isn't checked for flatness, that could cause it, too...



The heads were milled 15 thousanths and I checked the block with a straight edge and feeler gauge. I took an old head bolt and cut grooves into to use as a cleaning tap and chased all the bolt holes in the block. Service manual did not suggest the spray, permatex did. I replaced all head bolts as they are torque to yield.

I also cleaned the block by using a white roloc pad followed by a fine 3m sanding sponge.
 
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I would have even a new head checked to make sure the surface is flat. Check the deck too. Block and head must be clean. New bolts . What torque wrench? Is it's quality wrench? A cheap clicker may not be accurate enough for this. Lubed the head bolts?
 
Originally Posted by spasm3
I would have even a new head checked to make sure the surface is flat. Check the deck too. Block and head must be clean. New bolts . What torque wrench? Is it's quality wrench? A cheap clicker may not be accurate enough for this. Lubed the head bolts?



Didnt lube the head bolts since they went into the coolant jacket. Used an AC Delco digital torque reader for the first pass and a torque angle meter on the second pass.
 
Did you burp the coolant system once it was buttoned back up? Some older GM's has small bleeders to get the air out of the passages. Failure to bleed resulted in steam pockets that could ruin gasket seal. Don't ask me how i know this.
sick.gif
 
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Originally Posted by Hemispheres
This happened a couple years ago but it's always bothered me.

I pulled a head on my buick and found cracks between the valves so I replaced them. The head gasket didn't take on the front cylinder bank. I cleaned the bolt holes, used copper spray a gasket and took extra care to line up the dowel pins and gently place the heads on the gasket. Even torqued the head bolts to 37 lb ft plus 120 degrees.

After firing it up and test driving it I noticed a substantial loss in power. I pulled the front head and found a lot of coolant in cylinder number 5. The rear cylinder bank sealed right up without any issues.

What could of caused that to happen?




Can you clarify what you replaced ?
 
Originally Posted by Kawiguy454
Did you burp the coolant system once it was buttoned back up? Some older GM's has small bleeders to get the air out of the passages. Failure to bleed resulted in steam pockets that could ruin gasket seal. Don't ask me how i know this.
sick.gif



Yes I bled it.
 
Originally Posted by PimTac
Originally Posted by Hemispheres
This happened a couple years ago but it's always bothered me.

I pulled a head on my buick and found cracks between the valves so I replaced them. The head gasket didn't take on the front cylinder bank. I cleaned the bolt holes, used copper spray a gasket and took extra care to line up the dowel pins and gently place the heads on the gasket. Even torqued the head bolts to 37 lb ft plus 120 degrees.

After firing it up and test driving it I noticed a substantial loss in power. I pulled the front head and found a lot of coolant in cylinder number 5. The rear cylinder bank sealed right up without any issues.

What could of caused that to happen?




Can you clarify what you replaced ?


I got remanufactured heads.
 
The head could have been warped, the gasket damaged, dirt or foreign matter on the mating surfaces, torqued incorrectly, or at the wrong value, etc. Bottom line is it could have been a lot of things.
 
Brand new Toyota 22RE head gasket had a defect. It was a slipper plate design. Glad I looked it over real good because I think it would have leaked for sure. It was made in Japan. The replacement was still Toyota, but it was made in Thailand, and it looked exactly the same as the Japan made gasket. It's been working good for almost three years now.
 
Originally Posted by Hemispheres
Originally Posted by Astro14
Was the new head flat? Did you properly clean the block*? Did you clean the threads in the block*? Did your service manual suggest using that spray*? Does GM allow you to re-use the head bolts*?



*My quick search of Google on this topic suggests that you need to clean the block, chase the threads, use good gaskets (which means no spray ) and use NEW bolts.

Failure to follow those procedures will likely result in a gasket failure...and, of course, if the head itself isn't checked for flatness, that could cause it, too...



The heads were milled 15 thousanths and I checked the block with a straight edge and feeler gauge. I took an old head bolt and cut grooves into to use as a cleaning tap and chased all the bolt holes in the block. Service manual did not suggest the spray, permatex did. I replaced all head bolts as they are torque to yield.

I also cleaned the block by using a white roloc pad followed by a fine 3m sanding sponge.


Using a 120 grit ceramic roloc was the biggest mistake, that can ruin the engine in short order, not only that the require surface finish that insures proper gasket sealing got damaged. Never use a disc or sandpaper/block/sponge on an open engine.

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/Scotch-Brite-Roloc-Bristle-Disc/?N=5002385+3293223502&rt=rud

https://www.holmanparts.com/wp-content/uploads/2015/09/06_GasketSurface-Cleaning_V2.pdf
 
If you did everything right, it wouldn't be leaking.

Instead of arguing with Trav, who's done this a lot, and whose work doesn't leak, perhaps you should read what he posted.


Put differently: what would keep a new head gasket from sealing?

Here's a few things...off the top of my head...

Poor cleaning of sealing surfaces. Using sealants when none are recommended. Damage to the head. Damage to the block. Defective gasket. Re-using old bolts. Improper torque.

You've got at least one of those, and perhaps more. I wouldn't use abrasives to clean a block, or head, ever. Too much can go wrong.
 
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