LIM gasket and DEX info. Tell me what you think: - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 10-26-2007, 12:11 AM   #1
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Default LIM gasket and DEX info. Tell me what you think:

http://www.zillamotorsports.com/DEX

Post your own opinions Not web page design,but content.
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Old 10-26-2007, 12:43 AM   #2
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More then 1 set of each would have been an excellent start, I've seen non dex 95' L36s display far worse then his with similar mileage.

Like I said before, they didn't completely redesign the gaskets for no reason.
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Old 10-26-2007, 12:48 AM   #3
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While it wasn't the focus of your investigation, I'm wondering about the affects of heat soak, as well as expansion/contraction cycles during short trips on the silicone? Could this lead to slight leakage past the silicone that may not have been much of an issue with the old green stuff, yet assist in the deterioration of the plastic, and further break down with the Dex?

I'd suggest that you add the "all makes/all models" coolant as a recommendation. The Prestone Dex compatible is getting harder to find around here. Many of the service shops have also made the "business decision" of using that coolant, rather than stocking several types. This may save some people some headaches, or wasted time, searching for the Dex compatible, when something at least as safe is readily available.

Other than that, it is well written, and has good documentation to support your opinion/theory.

I could also supply pics of a LIM gasket from a '99 Olds 88 after 48k miles that look at least as bad as those. The Dex was flushed out after 3 years, but was added about 2 years later when the UIM work was done by a service shop. About a year later, the LIM gasket started leaking.
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Old 10-26-2007, 12:51 AM   #4
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The old green stuff isn't acidic.

Not only that, heatsoak between the S1 and S2 are no different. Expansion contraction cyles on the L36 and S2 L67 should be no different than the S1'*. Not only that, but heatsoak issues would be seen on the MIDDLE cylinder'* inlet, as it'* trapped between the other two cylinders. The #3 and #4 LIM port gasket area should run hotter than the other 4.
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Old 10-26-2007, 12:54 AM   #5
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Quote:
Originally Posted by White93z34
More then 1 set of each would have been an excellent start, I've seen non dex 95' L36s display far worse then his with similar mileage.

Like I said before, they didn't completely redesign the gaskets for no reason.
I've personally SEEN countless sets in over 5 years here, as has jr's3800. From a proof standpoint it would be nice to have more, but these gaskets were selected as 'typical' failures based on the combined experience of Don and I (and what I had handy).

There ARE exceptions. Poorly maintained cars without DEX, or non-DEX cars that had at one time seen DEX mixed in can degrade as well, but not typically until they get close to 100k miles.

DEX cars that survive longer are typically non-air-leakers that prevent the DEX inhibitors from turning acidic until later in life.
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Old 10-26-2007, 12:57 AM   #6
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Very good write up. I obviously agree with everything you have written and also have personal experience with the failed gasket having replaced mine last year with only 30 K miles after 6 years. The Dex was replaced but not completely flushed out after the first couple of years.
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Old 10-26-2007, 01:01 AM   #7
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Quote:
Originally Posted by willwren
The old green stuff isn't acidic.

Not only that, heatsoak between the S1 and S2 are no different. Expansion contraction cyles on the L36 and S2 L67 should be no different than the S1'*.
Exactly why I was wondering about that. If a little of the green stuff seeped past, no big deal...but could be more of an issue with an acidic coolant. In the case of green, if it seeps past to the intake on occasion, it wouldn't necessarily cause an problem. However, if Dex seeps past, it could cause an etching effect and sort of feed on itself. More of a thinking out loud than any real evidence that I have.
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Old 10-26-2007, 01:14 AM   #8
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Yup. It'* the reaction of acidic dex (when it gets to that point) against the known LACK of acidic resistance of Nylon66 (the material of the gasket carrier).
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Old 10-26-2007, 04:01 AM   #9
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That is a fantastic collaboration of comprehensive information. I bookmarked it and will be sure to spread the word on these gaskets. Its great to have an all in once source of information for Dex.

One thing I think should be added is a list of symptoms and tell-tale signs of imminent complete failure. Things like misfires, loss of coolant, etc. I know the main focus of the article is explaining, in depth, what the main cause is of these gasket failures, but it also wouldn't hurt to add in some effect. I read the whole thing, but maybe I missed the part where you might have added that in.
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Old 10-26-2007, 05:27 AM   #10
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Looks good I hope every one has looked at the Dex information at Cool Profits Magazine.

For some reason the link will not work but just Google “cool profit”.

http://www.imcool.com/

Remember that Dex-cool problems happen to other people not you.
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