Have you gone to more then one dealer? Some are way more helpfull then others.

 

What's with the *attitude* dude?
Maybe you should read this GM Bulletin..note that they use the term *POROUS* here:

www.tahoeforum.com - Chevrolet Tahoe / GMC Yukon Forum / Cadillac Escalade - View Single Post - Coolant loss with no external leak

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

 

There's a difference between a crack in the block and coolant flowing out the crack and having coolant magically flow through metal. Doesn't matter who wrote it, metal isn't porous.

 

go **** yourself douche bag.


any way. carl black of orlando is trying to get GM to pay for the repairs. I was charged 89 bucks to look at the motor. and so far the head gasket is blown. they havent checked the block yet. ill know tomorrow if GM will pay for it. they were very helpful so far. if not it will cost me about 2800 for new head. head gasket, intake gasket and a few other things. and labor

i really didnt think the head gasket could be bad. no smoke. no overheat. no signs of it.

thanks for the guys that are actually helping

 

Woah big man!

Ahh alright, I didn't realise helping you was only telling you things you wanted to hear; Far be it from little old me to even think about challenging theories you had about cars.

I mean let's face it "go **** yourself douche bag" is totally going to put a halt to even the most logical theories.

Hell even the GM guys replaced the most logical parts for you; Guess you better go after them for not replacing your leaky metal block because as we all know when your car gets too hot it sweats lmao

Not sure why you're so butt hurt since the comment I made had nothing to do with you, just a suggestion somebody made to "help" you. But hey, far be it from me
to share my thoughts on a forum.

I guess since it's sweating so much, you should pour some Gatorade or Sea Foam or whatever crap you kids are putting in your air/gasoline motors these days to keep it from sweating so much. I swear sometimes the reason some people believe this crap is because they took "Herbie The Love Bug" a little too seriously as a kid.

 

I blown gasket can leak out without signs if its small enough. That's really good news!

 

What causes the porus block to fail?

 

My point... the term*POROUS* is used for a condition of the block (or head) which is compromised to the extent that it can no longer contain the coolant (or oil) and *leaks* it into the combustion chamber. Nothing *magic* implied.

 

ahh my bad, I choose to use the definition in the dictionary... But if leaking between the metal is the same as leaking through the metal, I'm not going to judge. But the Chevy Cobalt was built in the real world; Just saying the folks on here need real world solutions to their real world cars.

Obviously the GM guy that wrote the article was in your world when he wrote that up.

 

You dont want "porous" block. It basically all your engine fluids mix together in a big soupy mess (coolant, oil, gas, water...) and everywhere in your engine is its playground.

combustion chamber, oil pan, turbo. lol.

I think the guys above explained it pretty well. Its happened to quite a few cars.. not enough to scare me yet. blow IC endtanks scare me more than porous block

 

Fine with me...

porous - definition of porous by the Free Online Dictionary, Thesaurus and Encyclopedia.

1. Full of or having pores.
2. Admitting the passage of gas or liquid through pores or interstices.
3. Easily crossed or penetrated

BTW read these articles and enjoy!
Do ya see *porous* anywhere?

The Cheesy Casting Ť Design-Construction

Porosity Classification System Helps Determine Solutions to Casting Leaks

 

Well you've successfully found two links to pages that incorrectly use the term "porous". That damage in those links was likely caused by cavitation which created cracks and fissures, not "pores".

 

GM Claimed my car to have the Porous Block issue which is a factory defect.

 

Bah, well I guess it's all semantics then. Since the coolant is leaking out of the cracks created in the process of casting, not through the metal.

I wouldn't call a crack in block a pore, that'd be like calling a gash in your leg a pore.

 

Well, as I have shown here this term is widely used for this condition....so next time you decide to *go off* and blast people, you might wanna *think about it* first.

 

Yeah I wouldn't want to hurt your ego...

If "porous" is easier for you to understand, then I guess I'll tell you I got a boo-boo when I cut myself, just so you don't confuse it with the black plague I'll send you links to places that use the term "boo-boo" for cuts and scrapes.

 

Actually, the block can actually weep coolant. The most likely cause I once stated was likely pouring too fast or pouring into a mold that was too cold. I've decided since that its actually because they didn't pour with the argon lance to displace the oxygen.

What we mean by this is during the process it's entirely likely the block had thousands upon thousands of microfractures. While it tested out fine, when it was put into service the heat and cooling cycles almost certainly widened the cracks, until they were big enough for molecules of water and glycol to get through. This is the very definition of the word porous. I'm not just some jackhole on the internet, I've been in the investment casting industry prior to my time in the army. I've learned about the process of casting both stainless steel and aluminum of ALL KINDS. If you cast without displacing oxygen in an aluminum pour, most times it's fine, but in engine blocks, that's not fine, since it WILL produce expanding fractures. Regardless of how you slice the term, coolant leaks internally, it's a known problem in LNF engines. It's even happened in other platforms, even MERCEDES had this problem a couple years ago. I might be able to link some examples of the problem some members are having, or had.

 

Did you read this post at all? You just perfectly described cavitation.

Since it's a forum, and I can be a jackhole; I can use links to Wikipedia articles like everyone else as definitive proof.

Cavitation - Wikipedia, the free encyclopedia

I'm not denying it doesn't happen, I'm just saying everyone is using the wrong term to describe it.

 

You still don't *get it* do ya? The more you respond like this, the more you confirm the fact that you're being a pompous ass. So be it.

 

Some larger diesel engines suffer from cavitation due to high compression and undersized cylinder walls. Vibrations of the cylinder wall induce alternating low and high pressure in the coolant against the cylinder wall. The result is pitting of the cylinder wall, which will eventually let cooling fluid leak into the cylinder and combustion gases to leak into the coolant.

It is possible to prevent this from happening with the use of chemical additives in the cooling fluid that form a protective layer on the cylinder wall. This layer will be exposed to the same cavitation, but rebuilds itself. Additionally a regulated overpressure in the cooling system (regulated and maintained by the coolant filler cap spring pressure) prevents the forming of cavitation.

From about the 1980s, new designs of smaller petrol (gasoline) engines also displayed cavitation phenomenon. One answer to the need for smaller and lighter engines was a smaller coolant volume and a correspondingly higher coolant velocity. This gave rise to rapid changes in flow velocity and therefore rapid changes of static pressure in areas of high heat transfer. Where resulting vapor bubbles collapsed against a surface, they had the effect of first disrupting protective oxide layers (of cast aluminum materials) and then repeatedly damaging the newly formed surface, preventing the action of some types of corrosion inhibitor (such as silicate based inhibitors). A final problem was the effect that increased material temperature had on the relative electrochemical reactivity of the base metal and its alloying constituents. The result was deep pits that could form and penetrate the engine head in a matter of hours when the engine was running at high load and high speed. These effects could largely be avoided by the use of organic corrosion inhibitors or (preferably) by designing the engine head in such a way as to avoid certain cavitation inducing conditions.

The above for relevancy, directly taken from your link is incorrect in the circumstances observed thus far. It is a casting process error that leaves both fractures and in some cases micro air bubbles trapped/formed within the casting. By process of heating and cooling repeatedly, having nothing to do with cavitation, it then leaks coolant out of otherwise contained passages. Thus described as porous.

Of course this is not to say the above couldn't happen, but this isn't what has been observed. I might also observe that cavitation described above to be enough to cause damage to the casting is a MASSIVE pressure differential something almost impossible to observe in a modern engine. And I suppose that entire passage needs to be rewritten correctly, the cap has nothing to do within it's prescribed purpose, it is indeed to prevent localized BOILING in parts of the engine that may observe temps higher than thermostatically controlled. That is just a single example.

 

dude it doesnt matter what damn term is used. i started this thread for some help from other members that have had this problem not for your dumb ass to get on here and try and be the cool know it all. this denlou guy is an idiot. just quit posting in this thread man

still waiting on GM to approve the dealer to warranty the work. while paying 40 bucks a day for a rental. =[ hopefully monday i get an answer!

 

Intersting info..
Does this usually appear within the first 5K miles or so? By that I mean...
if someone (ie, me) has gone 20K mi without a problem are they *out of the woods* with this, or can the problem surface at any time?

 

So one person gets upset that I hurt his feelings on the internet and the next is upset that I took his thread in a direction slightly different than he intended after no one took interest in his original question... oh wow...

 

Good luck..they should cover you on this. Suggestion....print out accounts from this web site on this problem as a back up.

 

I hate to try and challenge your opinions, because it upsets you, however in an attempt to actually help this guy are you seriously trying to tell the OP that things said on this meaningless forum are actually going to help him?

Quit being a whiney bitch and use the "report post" button then, that's what it's for.