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Old 10-28-2007, 11:35 PM   #61
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Quote:
Originally Posted by J Wikoff
Oh, I thought you were talking about the pic of the LIM gasket that had dark coloration around the coolant port.

Although, I don't see any problems related to the sealing material itself, other than it won't hold itself in place when the carrier material goes AWOL. My guess as to why the material changed was that type of rubber was easier to make a self-contained ring out of than the orange stuff.
I'll see what I can dig up tomorrow (it'* bed time for me), but I guess that kind of sums up how I feel this investigation has taken place - we see a change, and we wonder how it can be tied in to a problem with dex, and not the other way around. We don't look at the material change and say "why did GM change the material", we look at the material and think "they must have had to change the material so that they could wrap the carrier to prevent dex failures". It'* durned easy to do (for all of us), and it'* equally as easy to take the opposite view - how many possible things could have caused that change other than dex? In reality, we need to ask both sets of questions, and then figure out which one is right.

Again, I'll see if I can dig up anything more tomorrow. My personal gut? There was a change to the material to make it more dex friendly, and that was the only way to easily adapt the change to the existing carrier style.

Anyhew, I'll see you all tomorrow -
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Old 10-29-2007, 12:56 AM   #62
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Quote:
Originally Posted by mkaake
... No failures, gaskets all in tact. all Dex, and it ran the last month of it'* life before this operation with little to no coolant in the engine. Until the end, that is, when it was re-filled, which gave way to immediate UIM failure (or more appropriately, it had already failed, but had no coolant to show signs of failure).
Yeah, I'm the one who filled it up...

If I recall right, the car took a whole gallon to fill, at least. And it had just been driven up from Indiana. Nobody can say these 3800'* aren't tough...

The gaskets removed from this car looked bad to me at first glance, but it was just the molded-in reliefs I was seeing. Really, they looked pretty good.

Also, thinking more about the LIM gasket design vs. the change made to the UIM gasket'* water passages, I disagree with the assumption that the change made to the material and design of the UIM gasket was to prevent contact with DEX. It'* not impossible, it just doesn't seem logical to me.

Two reasons:

First of all, if that was the point of the UIM gasket redesign, I believe they could have done it using the same overmolding process as the rest of the gasket, and using the same material. I suspect it would have been cheaper and simpler (less labor). Therefore, I believe that the design change was to change the material, not to protect the nylon carrier.

Secondly, if they intended to protect the UIM gasket carrier from DEX, why not the LIM gasket? I don't see why they couldn't overmold the edge of the coolant passages.

I could be wrong, but I am now a doubter of the UIM gasket update being for the purpose of protecting the nylon from the coolant.

Sorry for the rambling, but hopefully it provokes some thought.
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Old 10-29-2007, 01:24 AM   #63
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Originally Posted by mkaake
Part of the reason I took a hiatus from posting here is because of the attitudes I still see in posts like this today - even when counterpoints are requested, they're treated as hostile, and the poster gets a wide range of verbal pepperings, depending on their standing here at the BC. It shouldn't be like that.
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Old 10-29-2007, 01:36 AM   #64
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I'm going to restrict the content of my reply for now. What I'm posting below is very carefully thought out.


1. Yes, there is apparently some great friction recently between billboost and I. Our qualifications and experience now seem to me be on the table for comparison as evidence in a debate about DEX-Cool.

2. The number of 3800 cars I've torn down apparently is of some concern to Bill Bostick. As if that was some point of comparison he thinks he'* got the upper hand in? I take it for what I know it is as well. That was a direct shot that he incorrectly thinks he'* got the upper hand in. Very few people here (maybe 2 at most) have an inkling of the true answer to his rather pointed question. I don't brag it, and I don't post it, so boosty better hope it stays that way.

3. THIS POST IS MINE. I posted some information on DEX that I spent a great deal of time investigating and researching. For over FOUR YEARS. More recently for reasons I'm not willing to get into for fear of inciting another riot. This topic was not meant to take personal shots at any member. It was (and was clearly stated as such) to open a discussion and debate about a chemical in an engine, not to say "who'* better than who". What a bunch of childish garbage this turned into while I couldn't sit here and babysit. The point was to get people to look into it for themselves.

GET THIS BACK ON TOPIC.
If anyone has any further personal shots at me for posting this topic, they can take them OFFLINE. All the rest that feel they'd like to continue to post ON TOPIC may conttinue to do so.
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Old 10-29-2007, 01:57 AM   #65
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I think, aside from this, a great way to prove this is with the scientific method, which you're doing, but you missed a key element: a controlled enviroment. If I really wanted to take it to the next level, I would put some nylon66 in a beaker of green, and some more in a beaker of dex. Heat them up to 195* for 3 hours every 6-12 hours for a few weeks, maybe months, and note the difference. I know I don't know much about engines, how they work or even how to fix them, but it seems that this would solve all of the controversy around the issue.

Just my two cents
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Old 10-29-2007, 03:22 AM   #66
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I haven't had the time to really read the replies today, so I'll do that tomorrow and give the responses I can in the most technical manner possible.

Any further personal shots or insinuations will be dealt with in the appropriate manner. This topic is intended to produce DISCUSSION of a very delicate and heated subject.

Anyone posting in this topic is expected to act like adult human beings from this post forward while discussing TECHNICAL information in a non-inflammatory or insuative manner.

For those that have posted in a technical manner, every member of this Forum thanks you. I intend to link THIS TOPIC to my web page so that everyone'* replies are recorded for anyone that may find my DEX page.
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Old 10-29-2007, 12:44 PM   #67
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Quote:
Originally Posted by petraman
I think, aside from this, a great way to prove this is with the scientific method, which you're doing, but you missed a key element: a controlled enviroment. If I really wanted to take it to the next level, I would put some nylon66 in a beaker of green, and some more in a beaker of dex. Heat them up to 195* for 3 hours every 6-12 hours for a few weeks, maybe months, and note the difference. I know I don't know much about engines, how they work or even how to fix them, but it seems that this would solve all of the controversy around the issue.

Just my two cents
I was actually thinking up of a similar experiment, except to test the weakness of the materials by measuring at what point they break apart on a pull test and post those numbers.
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Old 10-30-2007, 02:38 AM   #68
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Re-reading the article in question, I found a couple more nits to pick:

1) A Polymer is not the same thing as a Plastic. Close, but not quite. A plastic is a ploymer + additives (fillers, property modifiers, stabilizers, etc.). At the time a material is being molded, it is a Plastic, not a Polymer.

2) Just because Series I and Series II gaskets are both made using nylon carriers, that does not necessarily mean that they were both made using the same grade/brand/blend of nylon, or that they were both molded by the same supplier, or that both molds were well-engineered. All of these unknown factors can make a big difference in part quality! So to say that Series I and Series II gaskets are both nylon, and therefore the only difference between the two is the introduction of DEX, is to oversimplify things.

Then there are differences in engine design. Who'* to say that the intake side of the heads don't run cooler on a Series I? We can assume all day that they are the same, but do we know that? We may, but if we do, I haven't seen that thread mentioned yet...

Just some more things to think about. Not trying to be a naysayer necessarily. The more I think about it though, I believe that the gaskets are the bulk of the problem, and DEX just compounds the issue in some cases.
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Old 10-30-2007, 11:14 PM   #69
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My curiosity got the best of me today. I was cleaning the garage out, and ran across the UIM gasket from the job we did a few weeks ago on my mother'* 3800 (formerly my 3800, actually). The EGR portion of the UIM gasket was absolutely toast. That got me thinking - was it from the limited contact it had with the Dex (at super-heated temp levels, as any dex would have been in direct contact with the EGR pipe), or if it was from temperature alone.

So, I dug up some pics from 2004. Unfortunately, our 2 megapixel cams (near top of the line at the time) didn't have enough resolution for me to put my question to rest, so I figured I'd share a 100% crop:



The flakes are on the box beneath it. That said, I'm seeing what appears to be a chunk of gasket missing around the EGR port, while the coolant ports look pretty good (but again, it'* hard to tell, as I wasn't focusing on that area when I took the picture). Note: on this gasket, the UIM never leaked, so any damage to the EGR area is from heat alone.

Open for discussion...

As a quick personal thought, I'm leaning towards our biggest issues with the LIM gaskets being the reliefs in the nylon around the ports. Maybe theJMFC can post some thoughts on why they'd put that in the molding (edit: I think I found my answer... but I'd still like some outside feedback)? But in every pic of a dead gasket I've seen, there'* massive failure at those points. And in the microscope pic Willwren provided, the nylon was only corroded to that same distance from the bore.

*shrugs shoulders*
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Old 10-30-2007, 11:19 PM   #70
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I'm still in catch-up mode back about a page and a half, but I'd say from my knowledge of plastic molding and thermal applications that the reliefs are put in there for thermal expansion. I think it was a bad idea based on the fact that the intake ports are the coolest area of the gasket.

However, from what I've seen on multiple DEX gaskets (not just 3800'*), the failures don't start at those 'expansion slots'. The failure starts at the silicone rubber/Nylon interface.

On the UIM failure, I'd bet the bank on the heat from the EGR causing the damage at a much higher rate than the DEX eating through from the other side. The coolant temp is nowhere near the failure point of the base material, but the EGR temps can come close or overpower that spec.
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