diagnosing and replacing bad head gaskets

Grumpy · Jan 14, 2019

one rather common thing most guys , who build and play with muscle cars will eventually deal with is a blown head gasket.
I've put a few basic links below
The more common indicators are the engine runs like crap,
it misses and has steam or water vapor coming from the exhaust pipe
, but left un-repaired you find coolant loss, resulting in over heating,
and eventually coolant in the oil,that can cause rapid and serious wear issues.
and probably this will result in a great deal of other damage over a short time span.
if you suspect a blown head gasket, do the tests and repairs if required quickly.
IF you suspect a blown head gasket or cracked cylinder head,
Id strongly suggest, pull all the spark plugs and check for coolant in cylinders,
and do a compression test , all cylinders should read within 10% high to low,
on a compression test.
and if the engines been sitting long enough to cool off, remove the radiator cap ,
and look for oil in the coolant and along with coolant in the oil, or bubbles in the coolant,
you'll want to remove all the spark plugs and look carefully if any show signs of coolant contamination ,
thats a damn good indication the head(s) need to come off, for a repair and inspection.
keep in mind coolant getting into the combustion chamber can hydraulically lock up,and prevent the engine from spinning over,
and can bend connecting rods,or cracking a cylinder head, or the engine block, or damaging a piston and its rings.
and coolant in the oil rapidly deteriorate bearings and valve train components.
Id suggest draining the oil if you suspect a blown head gasket,
and looking for that all too common chocolate or rancid milk milkshake looking oil.
its a good idea to spin the engine over after all spark plugs have been removed,
\ to see if the engine pukes coolant out of one or more cylinders,
and if it does its going to require one or in most cases both heads,
to be refurbished and if it sat un-used the lower end bearings are suspected of corrosion damage.
if the head gasket has been in place for long with a flawed seal,
the high combustion pressures and temps can damage the block or head mating surfaces
(etching or cutting a recesed area) between the two in short order ,
so that area where the seal was lost must be carefully inspected,
and decking the block or head surfaces may be required before re-assembly can be done.
its rather common for coolant to be forced out of the cylinder(s) with the leaking head gasket ,
into other cylinders on the opposite bank, and they as a result,
can and frequently will require that cylinder head to be removed and refurbished as a result.
time is critical, don,t just park the car, figuring youll get to the repair as time and cash flow allow,
you need to drain the coolant in the radiator and engine oil, pull the oil filter,
and at least pull it down and closely inspect the potential damage!

related info
https://gobdp.com/blog/what-are-the-symptoms-of-a-blown-head-gasket/

http://www.themechanicdoctor.com/replacing-faulty-head-gasket-ultimate-guide/

http://knowhow.napaonline.com/eight-signs-blown-head-gasket/

https://www.enginebuildermag.com/2015/04/engine-block-and-head-repair/

https://www.felpro.com/technical/tecblogs/head-gasket-coolant-holes.html

http://garage.grumpysperformance.com/index.php?threads/sbc-head-gasket-choice.11070/#post-79067

http://garage.grumpysperformance.com/index.php?threads/head-gasket-related.1859/#post-50617

http://garage.grumpysperformance.com/index.php?threads/head-gasket.10085/#post-39429

http://garage.grumpysperformance.co...ad-gasket-for-aluminum-heads.4403/#post-26317

http://garage.grumpysperformance.co...asket-bore-size-vs-bore-size.2681/#post-11603

Depending on the severity of the leak, you may see bubbles in the overflow tank, indicating that the cylinder is leaking into the cooling system.
Blue exhaust smoke could also indicate head gasket failure, but so could worn rings, valve stem seals or a faulty PCV system.

diagnosing and replacing bad head gaskets

Grumpy

The Grumpy Grease Monkey mechanical engineer.