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Hey guys: I was wondering if we have any GM mechanics out there? I have a 2002 Buick with the 3.8 litre engine. I have an intake manifold leak. I was told I needed to have the "plastic" plenum replaced. I have been surfing the internet and found that GM has an ongoing problem with this and it seems it is due to the DexCool antifreeze that is used. This antifreeze supposedly causes ongoing problems. The mechanic I talked to said DexCool is the only coolant I can use. Why use an inferior coolant?? I noted that some GM owners went with normal antifreeze and experienced no problems. I get this new plenum installed on Monday. ($700) Would you tell the mechanic to install regular antifreeze? The car only has 70,000 miles on it. Thanks for the help. Ed
 

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Flush out the old and replace with Prestone. Seems like I remember reading that GM had problems with their anti freeze.
 

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I had a GM service manager tell me that the 'brown' new generation anti-freeze had problems.

He suggested I use the 'green' old type antifreeze. Since then I have used Prestone 'green' antifreeze.

We have a 2007 GMC truck with 5.3 ltr engine and a 2001 Buick with a 3800 II supercharged 240 hp engine. Both now have 'green' anti-freeze in them. The Buick was changed 5 years ago - no problems.
 

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If you go with the green make sure you flush ALL of the old coolant out or it will turn to a nasty gel and cause real problems.
 

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Esoxhunter, The reason the plastic upper intakes need replaced is NOT due to Dexcool or any other type of coolant. The exhaust gasses go into the plenum from the EGR valve, this exhaust chamber sits next to a coolant port and there is no metal sleeve to protect the plastic from the hot exhaust. Over time the plastic becomes very soft from the exhaust and eventually gets a pinhole in between the exhaust and coolant ports. What happens next is the engine sucks in coolant from the EGR port and will eventually hydrolock the engine. This is very common on the series 2 3.8 liter engines. Most of the replacement intakes will have a steel sleeve that goes into the EGR port to keep this from happening again. Shane
 

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Since I have an 02 LeSabre, and love the 3.8 it has, should I be watchful of changes in coolant levels?

And secondly, is there any type of preventative work that can stave off the eventual failure of the plenum?

I'm getting a lean condition code, must need an O2 sensor.

All else seems good at 70K miles.

HM
 

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Discussion Starter #7
Thanks a lot for the input. Hopefully I can get a few more comments on this. Shane: I have read that Dexcool has an adverse effect on gaskets and certain other parts. Some have said that they had the engine flushed and installed regular anti-freeze. Would regular anti-freeze hurt the engine if the Dexcool was flushed out? Ed
 

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Dex isn't the problem, it's as em described. Dex is a problem for those that think hoods aren't meant to be opened any longer, and things checked over. Air intrusion into the system containing Dex, is a problem, if left unchecked.

If Dex is removed, just remember you're not dealing with a 100K mile coolant any longer, green needs flushed every year if you don't want issues.

If you've got the blown 231, supercharged, this intake issue doesn't pertain to you.
 

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DEX Cool is and has been a problem for GM however a recall for this would ruin the company. Flush out all the coolant, refill the system with palin water and run at idel until normal operating temp has been reached drain the system again not just the radiator but remove the lower radiator hose as well reassemble and refill with the new add to any anti freeze/ coolant. flush and fill every three years.
 

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lean codes usually mean you have a lean condition as in vacuum leak . Usually at pcv and ctankcase vent hoses and on fords if no leak is found its usually the intake gasket o rings style gaskets
 
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