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I have a 96 regal and I have recently discovered that a bunch of brown gunk has built up inside the radiator and underneath the cap. I want to go about flushing it even though the engine does not overheat or shown any other signs of a bad cooling system. when researching online I have noticed a lot of controversy over the recommended dexcool and saw that this tends to happen in older gm cars that use dexcool when unwanted air is finding its way into the cooling system it gunks up and blocks up the passageways. After i found this out i inspected more and saw that i have puddles of what looks to be orange dexcool seeping from underneath the plenum. My question is do i need a new radiator or can I just flush the system? I think I caught it pretty early considering I couldn't tell it was bad until I opened the radiator cap. also what should I go about fixing first? and should should I upgrade to the aluminum plenum? I believe they updated the 3800s with the aluminum one after 2002 due to this same issue but I may be wrong.
 

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You'll want to start by flushing the system after the new parts are in, so you don't risk pushing more water into the oil than might already be heading that way. There's many videos on YouTube to choose from to guide this. It's best to refill with a mix of distilled water (~$1/gal at Walmart) and the "Any Makes/Any Colors" coolant, DexCool compatible without gunk GM ruined many engines with. Those 50-50 pre-mixes are like paying an extra $10 for each gallon of water in the end, so do it manually, and leave those jugs for people in a rush.

The main upgrade will be the lower intake manifold gasket change to updated AC Delco $40 aluminum ones that maintain integrity at the coolant passages. I'd also suggest an EGR block-off as well to eliminate a heat warping risk, which can be done for free. There's more custom work that could be done, but it gets slightly deeper into things.

It's not necessary to swap to the Series 3 L26 intake (2004+ Pontiacs, 2005+ Buicks), but if you want to find one cheap, you'd need to adapt a cable throttle body (typical to upgrade to 75mm Northstar one, since that's the Series 3 inlet size instead of the much smaller Series 2).
 
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Thank you! i'm starting the flush tomorrow morning and the manifold gasket and egr delete probably this weekend. l think i might also change out the old thermostat and gasket and replace the plastic elbows with the metal ones.
 

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Please re-read the end of my 1st sentence. I'd wait to push new water thru it until you've re-sealed things.
 

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2006 Buick Lacrosse 3.8L, 1996 Chev. Tahoe, 1933 Pontiac.
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dezldave961 is correct on when to flush the "whole cooling system", and that includes the heater core, radiator, and the engine block. If you flush the system before, you must do it again after you install the lower intake manifold. BTW: Change the oil and filter afterwards...before driving the car. When you have done all this, you will know the rest of the story.

AND!!!. The pink/red stuff in the cooling system is aka. "a dead engine will die sooner with Dex-Cool"
 

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Please re-read the end of my 1st sentence. I'd wait to push new water thru it until you've re-sealed things.
dezldave961 is correct on when to flush the "whole cooling system", and that includes the heater core, radiator, and the engine block. If you flush the system before, you must do it again after you install the lower intake manifold. BTW: Change the oil and filter afterwards...before driving the car. When you have done all this, you will know the rest of the story.

AND!!!. The pink/red stuff in the cooling system is aka. "a dead engine will die sooner with Dex-Cool"
So i should empty the coolant, clean out all the passages, replace the thermostat, metal elbows and all the gaskets, put it all back together and then flush? wouldn't that push the gunk through all my new parts and possibly clog them worse than what it is now?

I do also plan on switching to some universal green coolant once all the old dexkill is all flushed out. Although i'm not 100% blaming it because i don't know the full maintenance history of this car and the previous owner could have mixed coolants, put stop leak into it, or just neglected that coolant.
 

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Here is what I did to my 2006 Lacrosse CXL back when I replaced the plastic elbows at 24000 miles. I removed the thermostat, the hoses to and from the heater core, upper and lower radiator hoses from the engine block, drained the radiator, the coolant tank and flushed the heater core, radiator several times to get all the Dex-Cool out of the system. I installed the coolant elbows, install the hoses to the heater core, installed the upper and lower hose to the engine block, install the coolant tank, and a "new thermostat", and Prestone 50/50 antifreeze. BTW: stick the water hose in the "thermostat port" to flush the engine block so it flushed out the lower hose port.
In your case, I would the same as I had done. But do it after you have installed the intake manifold gaskets. Than change oil and filter.
 

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I personally don't think Dex Cool used properly, and maintained properly will have issues, it is when air is let get into the system, or not changing it on time, allowing the inhibitors to deplete lower than they should.
Adding additives, and or mixing coolant types that cause issues.
I have read all the arguments over the years, but I put 120k on a Park Ave, and I ran Dex Cool only, yes I had to replace the LIM Gasket, but that was from the constant heating and cooling of the nylon 6,6 framed gaskets.
Whatever you use just try to maintain it properly, and don't mix coolant types.

As for the EGR delete, you can do this, but if you get the Upper Intake Gasket Kit from Dorman, I am pretty sure it comes with a reduced diameter EGR tube, I used channel locks and tapped my old one out, then out the new one in place, out the old one over top of it, and tapped it down till it seated in the lower intake.
This keeps the hot gasses a bit further from the TB area that they effected...
 

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Lawsuits against GM, and their changing the formula used have proven they knew the additives in DexCool were the culprit for many problems, not just 3800 LIM gaskets.

Exposing a fluid to air ruins it? Making it incompatible for owners to not buy a universally available mixture that does the job as good or better? They made a faulty product that doesn't belong on Earth in our atmosphere.
 

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I have heard of the lawsuits, and maybe they had a good reason, I forgot about them changing the formula.
But yeah having air in the system is said to allow the coolant to become more acidic, and that along with the extra heat the system will have from air pockets is supposed to be harder on the system..
This is just what I can remember from stuff I have read over the years..
I know they still make and use it, and for as many as I see claim it ruined their car, just as many have used it properly and never had any issues..
I used it in my Grand Prix till I had a timing chain gasket leak that I did not have time to fix, so my mechanic I go to when I do not have time worked on it, and he flushed it and put green coolant in it, so I am going to stick with it...

I personally hate the Dex Cool argument because arguing solves nothing, some will sill use it, some will stop using it.
I just don't think there are issues if you properly maintain everything..
I could be wrong, but from the years I used it I never had it crud up, always stayed clear orange, and my rad stayed clean..
 

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Most who stick to using it tend to not be people who do much beyond "factory maintenance interval" adherence, and aren't the actual person performing the service beyond a surface level to know any better. Having shop-level experience and discussions with people dealing with things when they go south, it's very much a term that is spit out in disgust. Most shops will replace with the orange Dex-compatible fluid (Prestone or other) that's more universal, anyway, so most cars are now going around with a dilute-to-no actual remnant of that original formula. Sure, there's the pretentious crowd who think Mama GM does no wrong, and think they aren't ever putting out faulty products, but history says different.

I know it's weird to love these cars and still hate the various flaws they may have. It's still a powerplant that is much more suited to reliability and power in everyday use, versus building a ticking time bomb in a smaller displacement or race-only version of a bigger one. It fits a nice middle ground for those of us who know how to maximize the fun from them.
 
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You may be right, I have only personal dealings over the last 20 years, and I always do my maintenance myself, and almost every other thing done to my cars, provided I have time, and minus transmission or engine replacement, that I could probably do, but I don't have the time to try with how much I work...
I won't go back to Dex Cool on the chance so many claims are right, was just saying in my experience if you take care of the system like you are supposed to, then I think there is less of a chance of the sludge building up..
Now the EGR port, and LIM Gasket issues are a given, and I think they would happen over time no matter the coolant you use.
I think all car companies do wrong from time to time, I love my GM vehicles, but am far from a fanboy, I'd drive another vehicle if I had it without hesitation, I just would not know as much about its motor as I do the 3800 II and III
 

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Use it as a learning platform. The principles of how systems operate are universal, and knowing how the air/fluids need to properly move is something you can figure out across any engine. Limiting this to just 3800's would mean someone is more of a parrot of what's explained on these sites, more than actually understanding the operation of the engine overall. I don't think most people need to limit themselves like that if they want to explore automotive maintenance and performance.
 
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Thank you! i'm starting the flush tomorrow morning and the manifold gasket and egr delete probably this weekend. l think i might also change out the old thermostat and gasket and replace the plastic elbows with the metal ones.
One recomendation I would suggest is to completely drain the coolant and refill with water and use good cooling system cleaner. Run this until every thing is heated up and then do a BACK FLUSH of the entire cooling system(maybe rise it one extra time to be sure it's clean before installing new coolant. Good luck Jake...(mr goodwrench)
 

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I have a 96 regal and I have recently discovered that a bunch of brown gunk has built up inside the radiator and underneath the cap. I want to go about flushing it even though the engine does not overheat or shown any other signs of a bad cooling system. when researching online I have noticed a lot of controversy over the recommended dexcool and saw that this tends to happen in older gm cars that use dexcool when unwanted air is finding its way into the cooling system it gunks up and blocks up the passageways. After i found this out i inspected more and saw that i have puddles of what looks to be orange dexcool seeping from underneath the plenum. My question is do i need a new radiator or can I just flush the system? I think I caught it pretty early considering I couldn't tell it was bad until I opened the radiator cap. also what should I go about fixing first? and should should I upgrade to the aluminum plenum? I believe they updated the 3800s with the aluminum one after 2002 due to this same issue but I may be wrong.
you are s starting to see the design flaws in the upper half of those good old 3800 engines they start with elbows leaking ,then upper manifold leaking and valve cover leaks at times . if your handy you can fix it for parts cheap , if not the labor will out weigh the value of the car . A rock and a Hard Place. good luck
 

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Yup, $100-200 in basic fixes over an afternoon will set you up for 300k+ miles of glory. Unfortunately, most people just getting their hands on these cars did so because they were cheap 15-25yr old cars with a good reputation... but the basic maintenance on which that reputation was built tends to be ignored by many 3rd-4th owners.
 

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I got my current 3800 Series 2 about 3 years ago with 61k miles on it. It had basically sat in a barn most of its life. That said, it had the DexCool in it (probably from the factory) and I didn't see any corrosion or build-up. However; since I needed to replace the heater core + LIM gasket sets anyway, I opted to completely flush the system several times and then filled it with Peak's "every make, every antifreeze" coolant. (The yellow stuff.) I figured better safe than sorry. Just my $0.02.
 
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