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Old 10-26-2007, 08:36 AM   #11
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I like the write up. You provoke thoughts while drawing your conclusions.

Being a Gearhead here and seeing many, it brings up the question of your population size. Which is undoubtedly based on the number of vehicles you have seen. Here in the Northeast I've seen a lot of these and help a mechanic friend with many more. My experience is this:

1: The gasket collapsing is not a dex only issue. I have seen this on many 95'* which are and always have been green coolant cars. We can go round and round on "do you know if they were ever swapped" and the retort of "How do we know any of the good gasket vehicles never ran dex". Already there has been another poster to this topic with the same experience.

2. S1 to S2, gasket comparison in your example and worthy of being noted. It would be nice to see a comparison of the coolant flow. I have noticed the gaskets show more issues in the area #4 and #6 cylinders (which Todd from INTENSE specifically told me #4 runs the hottests of all the cylinders) Bill Buttermore did a flow diagram on an S2, do we know if anyone has done one on an S1?

3. Prestone LL, I disagree with your suggestion for the LL if the Dex acidity is your only reasoning for failure. I personally flushed my car to infinity (ask frozen fingers Tony) when swapping from Dex to Prestone LL. Approximately 1.6 years and 30K later I changed parts on my motor and found that with Prestone LL the gaskets were already collapsing noticably.

4. Too many anomolies. For each constant that we find in life, there is an exception. There are many exceptions to this gasket issue in S2 cars. Unexplainable exceptions, like ToastedOats: a guy that flogs his car around the Boston area of Mass using the (legal) breakdown lane as his superhighway. At 110K+ his gaskets looked new and we know his coolant to have never been flushed or changed. This is one example of say 15 that I have seen with the same nearly perfect gaskets.

5. Wicking theory, The wicking theory explains the collapse of the intake ports rather well. However, if that were the case..coolant would have appeared to have gotten into the air/fuel intake ports of the engine and would have been burning for some time in many of the vehicles I have seen. The intake ports with collapsed runners do not appear cleaner, no do the spark plugs, the exhaust didn't show any signs of coolant being burned and the coolant level never appeared to need topping off. Your theory uses a reasonable flow to conclude the difference in blocked port vs cooling port, that woudl suggest that the flow to these collapased intake ports was higher than a blocked port containing coolant. To further the wicking theory..how come no coolant wicks another 1/8-1/4" to the lower intake valley in your diagram. It is not a pressurized area and should show similar wicking as we see with oil on top of the LIM when the sealant on the bolts has failed.

6. Mechanics: I have asked about 5-8 mechanics about their theories on dex, the answer was mostly that if you maintained the coolant you would have no issue with the car as long as it was driven a reasonable amount. If your vehicle sat for long periods of time the Dex would probably turn into an oaty sludge in your cooling system. When pressed further on the gaskets, the answer was that the gaskets were "plastic" and had difficulty withstanding the rigors expected from them. Asked why a 3100/3400 gaskets failed they would typically leak. However being an aluminum top end on these motors vs our cast iron, there are many differences we can't possibly cover in one post. One of those differences is heat. Aluminum disipates heat at a much better rate than cast iron.

7. While collapsing or appearing to be in horrible shape...we find an extremely LOW number of problems that are directly caused by LIM gasket failure. The LIM gaskets in poor shape are obviously not contributing good to the motor, however they don't appear to be causing any issues.

To conclude what could be an even longer list of questions/observations, as a Gearhead here on this club I have learned much than ever expected about not only the 3800 but many motors in the GM lineup. In that learning process and in the spirit up the open forum for discussion and fresh ideas.....I've changed my original opinion of Dex being the sole or main reason for the gasket failure. the greatness of this forum is not to perpetuate a single idea, but help people and give them the opportunity to question things we believe are constants.

In the end....I agree that ALL coolants require maintenance at the given intervals or earlier (just like the lubrication system aka oil) and that within 3800'* LIM gaskets should be changed to the latest available updated gaskets from GM.
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Old 10-26-2007, 09:47 AM   #12
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In reply to Boosty above:

Quote:
1: The gasket collapsing is not a dex only issue. I have seen this on many 95'* which are and always have been green coolant cars. We can go round and round on "do you know if they were ever swapped" and the retort of "How do we know any of the good gasket vehicles never ran dex". Already there has been another poster to this topic with the same experience.
It is PRIMARILY a DEX issue. I clearly stated that there are EXCEPTIONS on both sides of the fence. The AVERAGE mileage of failure is what we're looking at, and Don and I combined our years of observation on this Forum. His 95 collapsed. But it was DEX. Yes, his car ran DEX for about 50k miles and his gaskets were crap. The average mileage of failure on the ugliest non-dex gaskets is about 100k miles. DEX gaskets look like that in half the miles or less typically. There is an undeniable trend that we're speaking about here. Don and I have seen countless cases in our combined 10+ years on this Forum to draw these conclusions from.

Quote:
2. S1 to S2, gasket comparison in your example and worthy of being noted. It would be nice to see a comparison of the coolant flow. I have noticed the gaskets show more issues in the area #4 and #6 cylinders (which Todd from INTENSE specifically told me #4 runs the hottests of all the cylinders) Bill Buttermore did a flow diagram on an S2, do we know if anyone has done one on an S1?
#4 runs the hottest because it'* trapped between two hot cylinders (2 and 6). It is also on the rear bank, and the rear manifold 'collects' the heat from the front as well as the rear, and is not in the direct air cooling path. #6 runs second hottest because of these reasons and it'* proximity to the crossover pipe. In addition, all the heat from the front bank (1, 3, 5) flows around the engine. On the front bank, #3 will run hottest due to it'* proximity to #1 an #5, 5 will be the next hottest, and 1 will be the coolest. The front bank in general will run cooler than the rear bank. So if #3 is the hottest on the front, and #4 is the hottest on the rear, why are the gaskets typically worse on the outer cylinders of each bank? Simple. The problem is not heat related. It may be made worse, but the problem is clearly linked to the proximity of the two coolant ports which are outboard of the outer cyilnder inlets.

3. What you need to know is what inhibitor Prestone LL uses. I haven't investigated that. The inhibitor that DEX originally used is known to soften plastic. Most competitors chose (for whatever reason) different inhibitors. You also may have flushed the bejesus out of it, and removed all or most of the liquid, but did you neutralize the acid coating on all internal parts? If you did, what did you do it with? The inner surfaces of cast parts trap pockets of acid. I found evidence of the same effect all over the gaskets I removed from EK98'* car. Crystallized and trapped between the Nylon carrier and the silicone rubber of the gasket. It was also obvious throughout his engine when we had it torn down. Until you remove or neutralize all this acid, you will still have the problem. In addition, which gaskets failed? OEM? OEM redesigned Nylon? or Fel-Pro?

Quote:
4. Too many anomolies. For each constant that we find in life, there is an exception. There are many exceptions to this gasket issue in S2 cars. Unexplainable exceptions, like ToastedOats: a guy that flogs his car around the Boston area of Mass using the (legal) breakdown lane as his superhighway. At 110K+ his gaskets looked new and we know his coolant to have never been flushed or changed. This is one example of say 15 that I have seen with the same nearly perfect gaskets.
As I clearly stated in my article, there are exceptions. Air is a big one, and none of us have control over air introduced in a DEX system. As I clearly stated above, the article was written on the combined experience and observations of Don and I over the last 5+ years on this Forum. I'm not dwelling on the exceptions. I clearly address them, but they don't point to the root cause, nor do they follow the clear trend. It'* the trend we're focusing on. Non-Dex gaskets don't erode and expose the nylon fibers that DEX gaskets do. Regardless of miles.

Quote:
5. Wicking theory, The wicking theory explains the collapse of the intake ports rather well. However, if that were the case..coolant would have appeared to have gotten into the air/fuel intake ports of the engine and would have been burning for some time in many of the vehicles I have seen. The intake ports with collapsed runners do not appear cleaner, no do the spark plugs, the exhaust didn't show any signs of coolant being burned and the coolant level never appeared to need topping off. Your theory uses a reasonable flow to conclude the difference in blocked port vs cooling port, that woudl suggest that the flow to these collapased intake ports was higher than a blocked port containing coolant. To further the wicking theory..how come no coolant wicks another 1/8-1/4" to the lower intake valley in your diagram. It is not a pressurized area and should show similar wicking as we see with oil on top of the LIM when the sealant on the bolts has failed.
Just because the coolant shows signs of wicking and port destruction doesn't mean it'* leaked YET. Some are replaced proactively (like this set from EK98'* car) and the leak in the intake runner is prevented. You won't see clean runners from a leak as obviously with DEX as you will with Glycol based coolant because the DEX turns to sludge when exposed to air. Wicking DID extend down to the lower trace by the lifter valley in this set. Look at the pictures again. One of the two gaskets in EK'* set is crumbling along the bottom edge. Note CRUMBLING. Not broken. Chemically and physically weakend. The question you have to ask yourself when you discover a set of gaskets like this in your car is "Did I catch it before it leaked?" and then you have to draw your conclusion by asking "Does it look like I caught it just in time before it did?". This set was caught JUST in time.

Quote:
6. Mechanics: I have asked about 5-8 mechanics about their theories on dex, the answer was mostly that if you maintained the coolant you would have no issue with the car as long as it was driven a reasonable amount. If your vehicle sat for long periods of time the Dex would probably turn into an oaty sludge in your cooling system. When pressed further on the gaskets, the answer was that the gaskets were "plastic" and had difficulty withstanding the rigors expected from them. Asked why a 3100/3400 gaskets failed they would typically leak. However being an aluminum top end on these motors vs our cast iron, there are many differences we can't possibly cover in one post. One of those differences is heat. Aluminum disipates heat at a much better rate than cast iron.
I've already stated in my offline debate on this subject with you that the exceptions exist, and a very well-maintained car would be one of them. However, this is no gaurantee because there are cases and variables you have no control over. If your mechanics that you discuss this with don't understand why they used plastic for this application, explain to them that it'* not plastic, but rather Nylon66, and share the melting point of that material with them. Too many people bitch about the gaskets without fully investigating them.


Quote:
7. While collapsing or appearing to be in horrible shape...we find an extremely LOW number of problems that are directly caused by LIM gasket failure. The LIM gaskets in poor shape are obviously not contributing good to the motor, however they don't appear to be causing any issues.
We've had our share. Mostly L67'*. The reason it'* mostly them is that the L36 crowd solves the problem when they get hit with the UIM failure.

Quote:
To conclude what could be an even longer list of questions/observations, as a Gearhead here on this club I have learned much than ever expected about not only the 3800 but many motors in the GM lineup. In that learning process and in the spirit up the open forum for discussion and fresh ideas.....I've changed my original opinion of Dex being the sole or main reason for the gasket failure. the greatness of this forum is not to perpetuate a single idea, but help people and give them the opportunity to question things we believe are constants.
Yes, we have come a long way. 5 years ago, we knew next to nothing on this Forum. Even a year ago, our knowledge was far more limited than it is now. Ultimately, Don and I are analyticals. We speak often and pick apart problems and solutions on the Forum that aren't even ours. That'* one of the reasons this article happened. You have obviously formed your opinion, and are determined not to change it, but there are other members of this Forum that may start to ask more serious questions based on the evidence I posted last night. Open-mindedness is the path to resolution or at the very least, greater understanding.

I have a question you never answered offline. You posted in a recent topic:
Quote:
Originally Posted by BillBoost37
We've also found and proven that Dex does not degrade the gaskets. Heat does. Either way the gaskets should be changed to the aluminum framed ones if they have over 100K on them.
I don't recall anyone proving that DEX doesn't degrade gaskets. Nor that anyone proved Heat does. Can you link me to this proof/study/topic?
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Old 10-26-2007, 10:04 AM   #13
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Bill...I'd like you to know I didn't post for you to analyze each point in a manner that would coincide with your article. You asked for opinions and ideas and that is what I supplied. My observations and thoughts about the subject at hand. It was not intended for you to rebutt and try to prove or disprove. I don't believe any of us are qualified (except maybe Matt) to render what is or is not fact as to the problem with the gaskets.

I will repeat though.. The gaskets look horrible... typically they don't fail.

As for the answering of the question.. you stopped replying to the offline PM debate/discussion. When you stop a conversation, it is expected that you may *

Have to run to a meeting.. to finsih later.
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Old 10-26-2007, 10:31 AM   #14
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Quote:
Originally Posted by BillBoost37
Bill...I'd like you to know I didn't post for you to analyze each point in a manner that would coincide with your article. You asked for opinions and ideas and that is what I supplied. My observations and thoughts about the subject at hand. It was not intended for you to rebutt and try to prove or disprove.
So if I understand this, you can Rebutt my article after analyzing each point in it, but I can't rebutt your rebuttal in my own topic?

Gotcha.

Moving on......
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Old 10-26-2007, 11:17 AM   #15
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I always like to see new info... I especially like the info on the Nylon 66 material... After learning and reading a lot more on different sites about Nylon 66, it throws a lot of variables right out the window..

Its interesting that the Oil Pan windage tray/gasket is made of the exact same material, as well the Upper intake gasket carrier and the Upper intake as well are made of the Nylon 66..

Now I can understand the issues with the with the EGR Port and Why GM went to a reduced diameter stove pipe...

Its very interesting to me at how the Same material in a couple hundred thousand miles of service parked in an oil pan is in great shape when remove( except for the crushed gasket part which causes an oil leak ).... So here we have an oil pan gasket, Lower intake gaskets, upper to lower intake gaskets, and for some a throttle body gasket all made of Nylon 66.... And the only ones that fail are intake gaskets..

Too many automotive companies these days are using many components made of Nylon 66.. Everything from Intakes to Thermostat housings and valve covers

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Old 10-26-2007, 11:27 AM   #16
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Quote:
Originally Posted by jr's3800

Its very interesting to me at how the Same material in a couple hundred thousand miles of service parked in an oil pan is in great shape when remove( except for the crushed gasket part which causes an oil leak ).... So here we have an oil pan gasket, Lower intake gaskets, upper to lower intake gaskets, and for some a throttle body gasket all made of Nylon 66.... And the only ones that fail are intake gaskets..

Too many automotive companies these days are using many components made of Nylon 66.. Everything from Intakes to Thermostat housings and valve covers
Another very good point.
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Old 10-26-2007, 12:40 PM   #17
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Originally Posted by willwren
So if I understand this, you can Rebutt my article after analyzing each point in it, but I can't rebutt your rebuttal in my own topic?

Gotcha.

Moving on......
No, you misunderstood and appear to have taken on a bit of sarcasm. I added my ideas w/o judgement or bringing about a definate conclusion with the exception that Dex does have downfalls and the LIM gaskets should be changed in nearly every case.

Don sparks another thought, the UIM to LIM gasket on the L36 is made of the same Nylon 66 as the LIM gaskets. Typically when I look at this area the concentration is on the UIM and not the gasket. Coolant is flowing at a good rate through this area. I have not seen a large number of leaks in this area...although we have definately seen some. Why don't we see the same level of collapsing inward plastic from inside the rubber area that we do on the LIM.

Could it be that the shape of the Nylon 66 has something to do with it. Inside the coolant and intake ports they have notches that almost look to be relief or break away areas and that'* typically where the problem appears to begin. At the UIM to LIM L36 gasket, the area is a circle and doesn't appear to collapse.

The aluminum gaskets have no notches.
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Old 10-26-2007, 01:01 PM   #18
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The difference in the coolant passages for the UIM gasket is that the Nylon66 isn't exposed to the coolant flow. It'* fully encapsulated in silicone rubber. I have a gasket at home to......wait.....have a pic here......

It depends on which gasket you get. And we run into more funny stuff. The original design of the gasket still had exposed Nylon66, but the silicone rubber seal is much more substantial:

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Furthermore, it'* probably typical for OEM setups to fail in the EGR stovepipe area first, and as a result of the repair, the UIM gasket never has a chance to fail. I personally don't have any proof that the OEM UIM gasket is Nylon66. I do know the LIM gaskets are, so this would take further research.

The new gasket design (OEM) for the L36 UIM solves the problem by changing the seal in the coolant passage so that the carrier isn't exposed to coolant at all:

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Another case of "Why'd they do that?" Why would GM want to remove the possibility for coolant to contact Nylon66 in the LIM and UIM gasket redesigns? That question has already been answered by two seperate distributors of Nylon66 who clearly state that Nylon66 is not resistant to acids. (again, assuming the carrier of the UIM gasket is indeed the same material)

My goal is to update the new page with information drawn from this topic. Including this UIM portion. I will also cross-link to our Techinfo #38.
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Old 10-26-2007, 01:23 PM   #19
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A couple of minor points:

First of all (not in the article, but in a previous post), someone mentioned that the LIM gaskets aren't plastic, but Nylon 66. Just so people aren't confused, Nylon IS plastic. Not all plastic is nylon, but all nylon is plastic. It'* just a variety of plastic.

Nylon does have a good chemical resistance, but not necessarily acid resistance apparently.

I do question the very narrow melt temp range given (I saw the source, but still...), since that would probably vary slightly by manufacturer, or the specific material used. Not really important though, since it'* too high to be a problem anyway.

The fibers that show up under magnification: Might they be glass reinforcement? Glass reinforcing fibers might (probably would) alter some of the other quoted properties of the nylon, especially tensile strength. By the appearance of the gasket carrier surface, I would not be surprised if there was some fiber glass content, but I haven't really studied it.

Looking at one data sheet for Chemlon 109-33 GH (a 33% glass filled nylon 66), the tensile elongation @ break is only 3.0%, compared to the quoted 15-80% in the article. However, the tensile strength is 20,000 psi. Not sure it matters in this discussion, but just wanted to put it out there. I assume those are dry ratings, but the sheet made no mention of moisture content. Nylon does gain strength/flexibility as it absorbs moisture (yes, nylon absorbs moisture, many common plastics do). We actually package some small nylon parts with a wet napkin, so that they will not crack during assembly.

I work in injection molding, so I am a bit of a plastics geek.

Otherwise, I generally support the theories in the article. I believe that the updated aluminum carrier gaskets are the final answer to this problem as far as the Series II is concerned (regardless of what coolant is used on the refill). We haven't seen a failure of them yet, have we? It'll be interesting to finally see what the second aluminum version changes...

Good write-up. Now add some CSS. :P
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Old 10-26-2007, 05:05 PM   #20
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Jon, you bring up some good points, and we're talking the same language. We have several types of plastics we use here, some glass reinforced, some not. In fact, some of them were acid-etched to promote adhesion until some really smart folks here started laser surface treating them to expose the top layer of glass fiber to produce the same effect with no chemicals.

But the meat of the matter isn't whether it'* reinforced or not. Either way, it'* still eroding, and either way, the main (base) material is still not rated for acid exposure. The fibers shown at 50x magnification may be glass, or they may be exposed strands from the manufacturing process that are only visible after the top layer is washed away.

It'* the combination of a coolant that is known to become acidic over time and a gasket carrier material that is known to react poorly in an acidic environment.

I'll be taking some of the key points and observations from this topic and adding them into the page either tonight or later in the weekend. Keep the discussion rolling.
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