View Full Version : porous/gasket
how (if possible) would i be able to tell the difference between a pooped head gasket and a porous head?
A porus head will tend to gunk the header tank with oil. Headgasket normally goes the other way and contaminates the oil with water, or pressurises the water system.
unfortunately you have to get the head taken off & pressure tested
A porus head will tend to gunk the header tank with oil. Headgasket normally goes the other way and contaminates the oil with water, or pressurises the water system.
UH.... OHH........
http://i69.photobucket.com/albums/i49/conad/DSC00345.jpg
http://i69.photobucket.com/albums/i49/conad/DSC00343.jpg
A porus head will tend to gunk the header tank with oil
As per Lee's post ^....... We have a winner :D
Nasty :(
Is it a Gm head?
**** FCUK BOLLOCKS!!!!!!!!!!!!!!!!!!!!! (appologies for the language)
Nasty :(
Is it a Gm head?
yup it 'was'.... coscast here we come
If you cant get your hands on a Coscast, source a normal head, get it pressure tested and it should last AT LEAST 50k miles+++
If you cant get your hands on a Coscast, source a normal head, get it pressure tested and it should last AT LEAST 50k miles+++
i want to eliminate the word 'should' and replace it with 'will' so im affraid coscast is the way forward
Just get a gm head and have a sleeve fitted to stop it cracking again.
Or have it done to your current head
Thought this car had already had the head done?
Yeah i'd go for a repair too.
meritlover
20-04-08, 09:34 AM
how (if possible) would i be able to tell the difference between a pooped head gasket and a porous head?
you take the head off.
there is no other method in finding out with the head on. either head gasket failure or porus head could give you water/oil emulsion depending on whether the gasket has failed between an oil way and water jacket, between oil jacket and bore, or bore and waterjacket. (or any combination)
i dont think you have considered a blown core-plug. this would allow the head to allow water to mix with oil in the rocker cover and the water jacket in the head. the emulsion you have in your tank is very severe. you should look at all possiblities before rushing out to buy a head!!
cav16 (google), on mig there is also a thread by joff_nova about fixing the "porous" issue.
by the way its NOT sodding porous, its a crack. 100% different issues.
Count Vaux Alot
20-04-08, 10:12 AM
I can get the head repair profesionally done sleeved etc for around £100 considerably cheaper than the £300 odd you would pay for a coscast and there is much less faf as you don't have to swap everything....PM me if anyone is interested i had mine done as a precaution and its a top job!
£100..... for £5 of bar and 10 mins with a drill........ foooooking ell thats a rip off.
Count Vaux Alot
20-04-08, 05:29 PM
/\ you get a pressure test and the drilling is done on a cnc machine plus a garantee and it wont be a fu=king bodge job by some chump lol lol lol
ahhh the good ole sales tactic of "it wont be a bodge" to try and justify it.
Is the guarantee only valid if they refit the head? If I were an engineering firm I wouldnt guarantee a repair like that unless I had refitted the head too.... too many variables in rebuilding the engine to just blame the repair job ;)
joffs thread on mig
http://www.migweb.co.uk/forums/engines-transmission/340906-thought-id-have-go-porous-cracked-head-modification.html
you take the head off.
there is no other method in finding out with the head on. either head gasket failure or porus head could give you water/oil emulsion depending on whether the gasket has failed between an oil way and water jacket, between oil jacket and bore, or bore and waterjacket. (or any combination)
i dont think you have considered a blown core-plug. this would allow the head to allow water to mix with oil in the rocker cover and the water jacket in the head. the emulsion you have in your tank is very severe. you should look at all possiblities before rushing out to buy a head!!
The nature of where the GM head fails means it will always blow oil into the water system. If you have oil in the water you can pretty much guarantee its a cracked (porus) head. Ive never seen a blown headgasket do the same thing if it goes across and oil/water gallery, invariably it'll gloop up the oil, or do both, but not just gloop the water.
The scenario you mention about the core plug doesnt add up as theres no water in the oil as far as we know :thumb:
Count Vaux Alot
20-04-08, 07:04 PM
ahhh the good ole sales tactic of "it wont be a bodge" to try and justify it.
Is the guarantee only valid if they refit the head? If I were an engineering firm I wouldnt guarantee a repair like that unless I had refitted the head too.... too many variables in rebuilding the engine to just blame the repair job ;)
joffs thread on mig
http://www.migweb.co.uk/forums/engines-transmission/340906-thought-id-have-go-porous-cracked-head-modification.html
Sorry for trying to offer a solution to a problem do it how you want it won't make any difference to me if it goes wrong, i'm sure your diy method will be fine. lol
not my DIY method :p
but certainly £95 cheaper than yours.... esp as there isnt any need for drilling lol
Philsutton
20-04-08, 07:33 PM
The nature of where the GM head fails means it will always blow oil into the water system. If you have oil in the water you can pretty much guarantee its a cracked (porus) head. Ive never seen a blown headgasket do the same thing if it goes across and oil/water gallery, invariably it'll gloop up the oil, or do both, but not just gloop the water.
The scenario you mention about the core plug doesnt add up as theres no water in the oil as far as we know :thumb:
Ive seen head gaskets go both ways, you can also do the head gasket without mixing oil an water. So many different ways they can fail, however if the head cracks it will go into the header tank as you say, but the gasket can also do that as well.
99% of the time it will be the head an not the core plug, these engines dont usually core plugs its very rare they do.
Ive seen head gaskets go both ways, you can also do the head gasket without mixing oil an water. So many different ways they can fail, however if the head cracks it will go into the header tank as you say, but the gasket can also do that as well.
99% of the time it will be the head an not the core plug, these engines dont usually core plugs its very rare they do.
You'd have much more experience seeing stuff like that than me :) But id still be surprised as the water is under a load more pressure coming up the block so it would have thought it would normally force its way into the oil at this point, rather than vice versa.
Agreed its not a foolproof diagnosis though lol
Count Vaux Alot
20-04-08, 09:13 PM
not my DIY method :p
but certainly £95 cheaper than yours.... esp as there isnt any need for drilling lol
Does it work?
have you even looked at the link?
Count Vaux Alot
20-04-08, 10:56 PM
Sorry i thought you had tried it....
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