i think all this headgasket talk all the time is funny most of the guys here have never done one which is fine but if so then take the advice given to you by (those who know). At work (toyota) we deal with this stuff all the time if you brought your car in to be fixed we use common sense we dont cut corners we use the right tool for the right job if you dont have the money wait till you do. You pay more when you do it twice dont just throw in a metal gasket if you dont have the proper prep it will leak. 90% of you dont need one a felpro or stock will seal up fine. If your car comes back then i work for free so no comebacks. Thus we replace parts as needed, this car is a in line 6 you will need a level surface have the head decked use a razor blade to remove material from the block, use a soft bristle wire brush. Clean up and call it a day when u remove fuel u (advance the timing) on a car with already agressive timing maps. Here is the reason for most problems get an itc or some way to counter act that an egt gague or knock link for those of you who know this sorry for the post.
Chip in the head near coolant passage.
- Thread starter bowsercake
- Start date
Aaron - I don't have to prove anything. DuPont specifically states acetone and ethyl acetate (both in contained copper spray) attacks Viton and causes it to swell. This is a fact, regardless of what your experience is, chemistry does not lie and it repeats it's effect consistently. The effect of air vs heat is irrelevant...by the time the motor is started after using the spray, the damage to the Viton is done. It doesn't take an "internet genius" to figure something like this out, just a little knowledge and research. Its well known that the aluminum head expands at a different rate that the steel block, creating a "scrubbing" effect between the surfaces. I can't figure out the logic of using a spray that contains chemicals that will soften (one of them a solvent for uncured Viton) the coating designed to seal the MHG against this scrubbing effect. You can do whatever you want for yourself and your other customers, but if I had you build a motor for me, I would specifically tell you not to spray the MHG. Reason why? Applying chemicals that DuPont says will swell/dissolve Viton is just plain stupid.
I also have experience...the difference is I take the time and effort to figure out why/how something works and the real cause. I don't beat my chest about how extensive my experience is...I don't have to, I'm smart enough to dig out the facts. FYI - I might not have pulled as many motors apart as you, but I have seen what copper spray does to the coating (both HKS and Cometic)...the effect was identical to what IJ experienced. Perhaps you might want to consider the Viton coating is holding up in spite of applying the spray.
Mattjk - Ask Chief Engineer Howard Hoshko why they do not put his recommendation on instructions for installing the gasket. Seems to me if this is a good thing to do, HKS would pass that along to their customers. And, if they recommend spraying the gasket, what's the point of coating it with Viton? Their website makes a point of why the coating is there:
Cometic says:
You're telling me that HKS engineers are saying the exact opposite? Or are you just pulling this out of your ass.
I also have experience...the difference is I take the time and effort to figure out why/how something works and the real cause. I don't beat my chest about how extensive my experience is...I don't have to, I'm smart enough to dig out the facts. FYI - I might not have pulled as many motors apart as you, but I have seen what copper spray does to the coating (both HKS and Cometic)...the effect was identical to what IJ experienced. Perhaps you might want to consider the Viton coating is holding up in spite of applying the spray.
Mattjk - Ask Chief Engineer Howard Hoshko why they do not put his recommendation on instructions for installing the gasket. Seems to me if this is a good thing to do, HKS would pass that along to their customers. And, if they recommend spraying the gasket, what's the point of coating it with Viton? Their website makes a point of why the coating is there:
Cometic says:
You're telling me that HKS engineers are saying the exact opposite? Or are you just pulling this out of your ass.
i agree with you on this but people think they are spraying on a sealer that might take care of a possible leak. Think of this a exhaust manifold with a small chip near a port will the spray sealer stop it from leaking no then why would it stop combustion pressurejdub said:Aaron - I don't have to prove anything. DuPont specifically states acetone and ethyl acetate (both in contained copper spray) attacks Viton and causes it to swell. This is a fact, regardless of what your experience is, chemistry does not lie and it repeats it's effect consistently. The effect of air vs heat is irrelevant...by the time the motor is started after using the spray, the damage to the Viton is done. It doesn't take an "internet genius" to figure something like this out, just a little knowledge and research. Its well known that the aluminum head expands at a different rate that the steel block, creating a "scrubbing" effect between the surfaces. I can't figure out the logic of using a spray that contains chemicals that will soften (one of them a solvent for uncured Viton) the coating designed to seal the MHG against this scrubbing effect. You can do whatever you want for yourself and your other customers, but if I had you build a motor for me, I would specifically tell you not to spray the MHG. Reason why? Applying chemicals that DuPont says will swell/dissolve Viton is just plain stupid.
I also have experience...the difference is I take the time and effort to figure out why/how something works and the real cause. I don't beat my chest about how extensive my experience is...I don't have to, I'm smart enough to dig out the facts. FYI - I might not have pulled as many motors apart as you, but I have seen what copper spray does to the coating (both HKS and Cometic)...the effect was identical to what IJ experienced. Perhaps you might want to consider the Viton coating is holding up in spite of applying the spray.
Mattjk - Ask Chief Engineer Howard Hoshko why they do not put his recommendation on instructions for installing the gasket. Seems to me if this is a good thing to do, HKS would pass that along to their customers. And, if they recommend spraying the gasket, what's the point of coating it with Viton? Their website makes a point of why the coating is there:
Cometic says:
You're telling me that HKS engineers are saying the exact opposite? Or are you just pulling this out of your ass.
^^^ This is true...it doesn't work. Prep for a MHG is key...or use a stock composite HG. You can spray that all you want.
I have no dog in this fight but it's well known acetone is incompatible with fluorocarbon (Viton is a Dupont trade name) elastomer. Any chemical compatibility chart will show this. For example:
http://tinyurl.com/2yhtop
or
http://tinyurl.com/2yq3zg
Fwiw when I worked as a machine design engineer in the semiconductor industry we dealt with all sorts of seal materials and specifically avoided using acetone around fluorocarbon. All that said I have no idea what's used in copper spray or similar sealers to keep the product in suspension. That can easily be found by checking the CAS numbers of the product in question.
http://tinyurl.com/2yhtop
or
http://tinyurl.com/2yq3zg
Fwiw when I worked as a machine design engineer in the semiconductor industry we dealt with all sorts of seal materials and specifically avoided using acetone around fluorocarbon. All that said I have no idea what's used in copper spray or similar sealers to keep the product in suspension. That can easily be found by checking the CAS numbers of the product in question.
Or by reading the back of the can
Like the can of Permatex Copper Spray-A-Gasket I'm holding in my hand right now:
Of course JJ, I suppose other folks "experience" will prove this as incorrect as well...the spray can't possibly contain anything that will attack fluorocarbon based elastomers
Like the can of Permatex Copper Spray-A-Gasket I'm holding in my hand right now:
Of course JJ, I suppose other folks "experience" will prove this as incorrect as well...the spray can't possibly contain anything that will attack fluorocarbon based elastomers
I know we all agree that surface prep is extremely important. And for the origional post in this thread I wold recommend getting that welded. I'm not arguing with the chemical science posted, my issue was with Jdub saying the copper spray on a mhg will CAUSE head gasket leaks, which is just not true. I have found it to be exactly the opposite. If the Viton layer is only .001" thick, what happens if you have small imperfections in the aluminum that are .002" deep?
Ugh. Dichloromethane is bad stuff. Bad for humans that is. No huffing allowed . And yeah, ethyl acetate makes that can a double whammy for fluorocarbon.
. And yeah, ethyl acetate makes that can a double whammy for fluorocarbon.
So what's the point of the Viton Aaron? If you're going to use the copper spray, clean the Viton off the MHG...what I can't figure out is why you would want a chemical "goo" as the seal for your HG. You're defeating the purpose of the Viton, and yes, that can very easily cause problems with the seal.
If the head/block meets the RA spec for the MHG, the Viton is plenty good enough for the seal. If you have imperfections of any size in the area around the cylinders, they should be welded prior to re-surface.
On composite HG's or used MHG's, using the copper spray is fine. I use it on both, especially on a used (well cleaned) MHG to replace the Viton.
If the head/block meets the RA spec for the MHG, the Viton is plenty good enough for the seal. If you have imperfections of any size in the area around the cylinders, they should be welded prior to re-surface.
On composite HG's or used MHG's, using the copper spray is fine. I use it on both, especially on a used (well cleaned) MHG to replace the Viton.
If it helps I'm using the GReddy MHG. Not sure if they use the Viton sealant or not. I can't find any information on their website and I don't really fell like scratching at mine.
Like JJ said, Viton is a Dupont trade name...all MHG's use some type of fluorocarbon elastomer to effect the initial seal.
Um.. I wouldn't just toss that head at a machinist and hope they could weld it properly!
You've got to be meticulous about it - and that's something I've seen a lack of in my own local machinists.
Make sure they are tig (aka heliarc) welding. If the head is not heated, welded, then cooled slowly, the 'repair' could crack and fail again.
Nevermind the aluminum oxide layer that *must* be cleaned off, as well!
You've got to be meticulous about it - and that's something I've seen a lack of in my own local machinists.
Make sure they are tig (aka heliarc) welding. If the head is not heated, welded, then cooled slowly, the 'repair' could crack and fail again.
Nevermind the aluminum oxide layer that *must* be cleaned off, as well!
jdub said:
obviously cometic is using a different fluoroelastomer than hks. I believe hks uses a variation of viton extreme, which is very resistant to petroleum distillates:
http://www.dupontelastomers.com/Products/Viton/News/articles.asp?article=larius
http://www.dupontelastomers.com/products/vitonapa/techinfo.asp
you're probably right, copper spray is probably bad for the coating used on cometic's mls gaskets, but it is fine on the hks.
mattjk said:
Ok...so you made me dig
Following the links you provided, I registered on DuPont's site to gain access to their application guide and chemical resistance data. You are correct, Viton Extreme TBR is used in automotive applications...nothing specific concerning MHG's. Viton Extreme ETP is used in harsh environments where flexibility and chemical resistance is important....the applications listed were in the oil & gas industry (primarily O-rings); none for automotive.
Here's what I found in the chemical resistance data for the various types of Viton...specifically for Acetone and Ethyl Acetate:
Note that all types of Viton, except Viton Extreme ETP is not recommended for service in the presence of Acetone or Ethyl Acetate due to a >50% volume swell due to either of these chemicals. The bottom chart show the volume of swell for the various types. Even Viton Extreme ETP (not used in automotive applications) will swell 19-25% in the presence of Acetone and 23-24% in the presence of Ethyl Acetate.
Considering the above, I am very skeptical that a HKS engineer would recommend using a spray sealer that contains these chemicals on any fluorocarbon elastomer used to coat a MHG. Just to be certain, I e-mailed HKS in an attempt to get their response concerning use of a spray sealer containing Acetone and Ethyl Acetate. I also asked what type of fluorocarbon elastomer HKS used on their MHG's. Hopefully they will respond.
good luck with that, the new hks people are clueless.
Not trying to argue with you, but MANY people use copper spray on hks gaskets with good success. It's just my actual real world experience, and also Aaron's.
Honestly though, you make it sound like you're dumping straight acetone on the gasket... the ethyl acetate and acetone is used the keep the product in a sprayable state. It evaporates very fast.
Not trying to argue with you, but MANY people use copper spray on hks gaskets with good success. It's just my actual real world experience, and also Aaron's.
Honestly though, you make it sound like you're dumping straight acetone on the gasket... the ethyl acetate and acetone is used the keep the product in a sprayable state. It evaporates very fast.
ok so let me be sure i am clear minded:
Many people have had sucsessful results using the spray on MHG's. real world data. Saying it can work,(work dam well) and is absoluly possible. (Does everyone agree to let spray tack up or not?)
Now "science"(chemical properties?) say that its a bad idea, and should not be used. that is what the "type of fluorocarbon elastomer" on the MHG is their for. and such sprays will react in a negative manner.
If re-using a MHG that is super clean and not deformed then such a spray may be used in place of the "type of fluorocarbon elastomer".
Also: Head and block prep work is a must!(stating the obvious.) Sorry for the simple mindedness, but now information is more stupid proof.
To thread starter: I would attempt to have that fixed, taking into account that welding is obvioulsy a trade skill, and you have to have someone that knows exactly what they are doing.
Many people have had sucsessful results using the spray on MHG's. real world data. Saying it can work,(work dam well) and is absoluly possible. (Does everyone agree to let spray tack up or not?)
Now "science"(chemical properties?) say that its a bad idea, and should not be used. that is what the "type of fluorocarbon elastomer" on the MHG is their for. and such sprays will react in a negative manner.
If re-using a MHG that is super clean and not deformed then such a spray may be used in place of the "type of fluorocarbon elastomer".
Also: Head and block prep work is a must!(stating the obvious.) Sorry for the simple mindedness, but now information is more stupid proof.
To thread starter: I would attempt to have that fixed, taking into account that welding is obvioulsy a trade skill, and you have to have someone that knows exactly what they are doing.
Pretty much correct...Cometic specifically says not to use a spray sealer. Still have not heard from HKS.