By on July 21, 2009

Darwin S. writes:

I have a 1999 Buick Century that now needs constant water. It happens pretty slowly. I recently drained all the water and refilled with water and antifreeze. It doesn’t appear to be leaking anywhere. What’s happening? Thanks.

Sajeev answers:

There are three possible reasons for your Buick’s dehydration.

1. An external leak—which isn’t the problem here.

2. The coolant is pouring into your oil via busted gasket. If so, please accept my apologizes for not getting to your query sooner. Now’s the time to get a locally sourced “LKQ” replacement motor.

3. You’re burning coolant along with gasoline. White smoke from the tailpipe is your best indicator.

If your problem is behind door number three, it’s not the end of the world; new head gaskets are usually the solution. Do a compression test and pull your spark plugs to find the offending cylinder.

Depending on your Buick’s motor, the intake manifold gaskets might be the problem; this was the case with earlier versions of the GM 60-degree V6. Put another way: can Government Motors interest you in one of their new, 90-day-inventory Buick LaCrosse sedans? It’s better than the Century in every way, save for the stupid name.

Bonus!  A Piston Slap Nugget of Wisdom:

When seeking the answer to life’s unsolvable questions, always consult your spark plugs. They won’t know if you’ll land that great job, or when you’ll get laid (off), but checking your plug’s condition is like a fortune cookie for your motor.

For the tin-foil hat fans in all of us, checking platinum plugs before 100k miles is a good idea. Well, provided your whip doesn’t require an Act of Congress to remove them. In those cases, just change according to the owner’s manual and hope for the best.

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25 Comments on “Piston Slap: The Centurion Loses Its (Dex) Cool...”


  • avatar
    Ronman

    can it be as simple as the radiator cap leaking a little, and then they dry as soon as they hit the radiator, it could be hard to detect? it happened with me in an old Chevy… drove me nuts, compressed the system by placing a pump on where the cap goes. everything checked out, because the cap was the problem. discovered it by total accident.. it’s worth a check..

  • avatar
    Orian

    If it is like the 3.4l v6 it may very well be the lower intake manifold gasket. GM had a huge issue with this from around 99 to 2003/2004 time frame. I’ve been very lucky with my 04 Grand Am in that I’ve put 95k miles on it and so far (knocks on wood) my lim gasket has not failed yet.

  • avatar
    Daniel J. Stern

    Dex-Cool = Death-Cool. It eats critical things like gaskets and radiator junctions. I can be a little slow at times; it took me four head gaskets and a smattering of other failures before I accepted the coolant chemistry as the cause. Changed back to ordinary green coolant and suddenly quit losing gaskets, seals, and junctions. This was before the advent of the G-05 type coolant, which I presently use with no problems.

  • avatar

    The 3100 V6 in the Century also had gasket issues.

  • avatar
    spatula6554

    I agree completely with Mr. Stern.

    I have driven a 1997 Monte Carlo LS (3.1L V6) for the past 5 years, purchased it used from an acquaintance at 100K miles. The Dex-Cool ended up eating through gaskets before I knew there was an issue…I found myself low on coolant, with murky, milky oil. Eventually blew a conn-rod because I was a young and foolish kid.

    Had to go out and get a Jasper motor installed, best thing I ever did with that much money.

    There is actually a lawsuit that was being handled against GM for their Dex-Cool ineptitude. I was in contact with the law firm (Girard Gibbs and De Bartolomeo LLP) but the deadline to file for cash reimbursement has passed (10.07.2008).

    Now on their settlement website, it lists the “Old GM” default scapegoatism…

    http://www.dexcoolsettlement.com/

    I do hope it isn’t getting into the crankcase…good luck!!

  • avatar
    mattstairs

    Spatula6554, that’s very interesting. I had a ’99 Grand Prix with 3.8L V-6 that I broke a rod in too. I wonder if a coolant leak lead to that? Fortunately it was still under warranty.

    I remember smelling coolant at times after running the A/C on a hot day. Has anyone else had that experience with DexCool?

  • avatar
    John Horner

    The GM 60 deg. angle V-6 engines of that era have a nearly 100% failure rate of the intake manifold gasket, and it fails in such a way as to let coolant into the motor oil. The tales of woe are found everywhere. This is a typical thread:

    http://www.gminsidenews.com/forums/f53/intake-manifold-leak-14429/

    Take off the oil filler cap and check for a milky brown residue. If so, it has already gotten pretty bad. If the contamination isn’t that severe yet, do a $25 oil analysis to check for signs of anti-freeze in the oil. http://www.blackstone-labs.com

    The 3.1l engine also is notorious for head gasket leaks. GM’s band-aid for years has been supplemental sealing tablets dropped into the cooling system. You know it is bad when the factory is putting those magic cooling system additives in themselves!

    Here is a pretty good tutorial on how to change the intake gasket, written on a site designed to help shops make more money (no lie!).

    http://d-tips.com/General/Articles/article.aspx?id=/free/How%20to/Chevrolet%203.4%20intake%20manifold%20Gasket/art10.art

  • avatar
    JMII

    Our VW Passat does this… ever so slow coolant is escaping somewhere. Local dealer can’t find a leak and the garage floor is clean, so I just carry an extra jug of coolant around and top off as necessary (about once every 4 months). I figure one day it will just blow up, after all its pushing 75K on the 1.8T everyone swears is a POS. Still getting 30 mpg so I’m not complaining (yet).

  • avatar
    Steven Lang

    Orian’s take is actually the most common with GM vehicles. Apparently someone in the GM hierarchy decided to make it out of plastic instead of steel.

    Get it looked at by an independent auto shop that does not have a big brand name in front of it. ‘Marietta Automotive’ or some other neighborhood place that’s been around for a long time should be fine.

  • avatar
    RayH

    A quick and cheap fix: 2 tubes of Alumaseal. It looks like sand, comes in a tube just above the size of a roll of quarters. In conjunction with a good coolant flush beforehand (and not reusing dex-crap), it’s a sub-$80 buck repair that will get you a good year or two before you have to do it again. Pour it into the top of your cool radiator and drive the hell out of your car for an hour to mix it in good. Admittedly, this will make your water pump whine and eventually take a dirt nap in 3 or 4 years.

    *disclaimer: I don’t own stock in whomever makes Alumaseal. I have done this process on multiple late 90′s GM products of mine and friends with the 3.1 and 3.8 engines (maybe a 3.4 too). It’s hard to stomach the $600+ repair when the car has already had water in the oil, and tearing down further to find any damage $300 more. The only issues over the years observed have been 1 dead waterpump (all did eventually whine) and a clogged heater core (blown free with compressed air).

  • avatar
    superbadd75

    Dexcool is fine now, guys. The old stuff would go to shit when mixed with chlorinated water, the new Dexcool does not. The old stuff would have been okay as well, if people actually followed directions and only added distilled water, but unfortunately it was usually miffed at the dealer during the PDI, and went downhill from there. Anyway, don’t fear the Dexcool, it’s been reformulated since 2005. It’s all good.

    As for the coolant, I’d say intake gaskets. They can leak for quite a while undetected (no drips), and when the car is driven, the coolant evaporates. That’s more likely with your car than anything else. After checking that (if you come up empty), then I’d check into the head gaskets. Check for exhaust gases in the coolant (you can usually get a test kit at NAPA), and possibly have a block test performed after that. My gut says it’s going to be the intake gaskets though.

  • avatar
    Daniel J. Stern

    @superbadd75:

    Dexcool is fine now, guys. The old stuff would go to shit when mixed with chlorinated water, the new Dexcool does not. The old stuff would have been okay as well, if people actually followed directions and only added distilled water

    Yeah, I’m sure it’s fine now, just like it was fine (the newest! The best! Much better than the old kind!) back then. The problem with your explanation is that I used only distilled water to mix my Dex-Cool.

    Anyway, don’t fear the Dexcool, it’s been reformulated since 2005. It’s all good.

    Uh…none for me, thanks, I’m driving.

  • avatar

    Best long term solution avoid GM cars like the plague and don’t believe their claims about long term quality and durability.

  • avatar
    beken

    You had to bring up a 1999 Buick Century.

    The 1999 Buick Century is the car that drove me away from GM permanently. I no longer have it, though if things didn’t keep breaking on it, it could have been a pretty good car. The last 3 years I owned it, whenever something was fixed(usually major) on it, something else would go shortly afterwards. Being the persistent lout that I am, I kept telling myself if I fixed this, the car should be fine. Was I ever wrong. Buying and owning a new BMW was less expensive than keeping the Buick running. I had almost rebuilt the entire car by the time I got rid of it. Everything from melting lightbulb sockets (that cost $50??!!! each) and head gasket jobs, that get VERY expensive. You never know what else might be wrong once they open er up.

    I should have known this was a bad car when I had to replace ALL the wheel bolts while the car was under warranty, and GM would not honor the warranty on them, claiming they were wear and tear items, even though they were breaking.

    As nice a drive (comfy and quiet) as this car is, I would recommend you start looking for another car.

  • avatar
    spatula6554

    No more Dex-Cool for me, no matter what the Manufacturer recommends.

    @superbadd75:

    Dexcool is fine now, guys. The old stuff would go to shit when mixed with chlorinated water, the new Dexcool does not. The old stuff would have been okay as well, if people actually followed directions and only added distilled water

    As an engineer, I have been trained to always design products for the dumbest individuals who could use it. Make things so simple, that you could not screw it up if you tried. Apparently GM missed this class in school because they should have realized that the mechanics and people servicing their cars have been using chlorinated tap water with glycol for coolant for decades. Why would they notice something as subtle distilled water in directions?

    Anyway, don’t fear the Dexcool, it’s been reformulated since 2005. It’s all good.

    Why would I continue to use something that caused me that much frustration in the past? I understand that it has been reformulated, I understand that it has been changed to conform with the existing standard. But why would I allow GM the satisfaction of spending my consumer dollars and my taxpayer dollars?

  • avatar
    dolorean23

    Check the Head Gasket. Every GM I’ve ever owned or known had a leaky head gasket when it got up in miles. Its a bitch to replace, but you can DIY. While you’re there, take a look at your exhaust manifold cause I’ll bet $$$ that there’s a hole in it by now.

  • avatar

    This thread is far more depressing than I expected.

  • avatar
    walksatnight

    Might as well throw a new O2 sensor into the kitty along with the manifold gasket.

  • avatar
    Power6

    Orian’s take is actually the most common with GM vehicles. Apparently someone in the GM hierarchy decided to make it out of plastic instead of steel.

    There is nothing inherently wrong with plastic intake manifolds. A bad design is a bad design no matter what the material…and those V6s had plenty of gasket issues when the manifolds were aluminum…

    I must be too young, never seen a steel intake manifold…

  • avatar
    golden2husky

    We have the exact car pictured. 1999 with 140,000 miles on it. Had the damn intake gasket done twice. For the second time, the Dex Death was flushed out for good and replaced with universal fill. So, that adds up to $1,500 in repair. The sad part is that the intake fiasco was the only repair of any significance on the car. Yes, the interior is cheap, but the car has been very reliable and has a lot of features for the money. I am partial to GM’s 60 degree V6′s. Underhood is intelligently laid out and easy to service. Hate the suspension, though. Way too mushy but not my car to drive. I wish all my cars were as easy to work on.

  • avatar
    John Horner

    “The old stuff would have been okay as well, if people actually followed directions and only added distilled water ….”

    Unfortunately that isn’t true. Our Olds minivan had all kinds of horrible brown gunk in the cooling system at two years of age, and that was with the factory fill coolant and no tap water ever used. The same van had a leaking intake manifold gasket by 40k miles from new.

  • avatar
    Tecant

    We had leaking coolant issues on our 2000 Chevy Malibu (3.1 60 degree V6). The Chevy dealer estimated $750 to replace the intake manifold gasket. Since this car had suffered a transmission failure at 54K the year before, we went down the street and traded our Chevy in on a Hyundai. This coolant leaking problem has been so common that the Hyundai mechanics look for it whenever someone wants to trade in a GM car. In 5 years of ownership, our Hyundai has been trouble free.

    Previously we had owned a Chevy Celebrity and a Lumina minivan, both with the 60 degree V6. We sold them at 156K and 179K, respectively. In our experience, the drivetrains in those cars were bulletproof. GM had it right and screwed it up. They’ve lost us as a customer forever.

    My brother-in-law had a Chevy Venture minivan with the 3.4 V6. After replacing the intake manifold gasket twice he got rid of the van. When his teenagers needed a car, he bought a used Hyundai which has served them well so far. Another customer lost to GM.

  • avatar
    GS650G

    Set fire to the buick. Toast marshmallows on the burning carcass.

    Check the resale price of this car. It’s about scrap metal in value.

  • avatar
    Omnifan

    Now’s the time to get a locally sourced “LKQ” replacement motor.

    NO! Beware of any used parts from LKQ. They don’t test them well and won’t stand behind warranty!

  • avatar
    ohsnapback

    Dexcool; what an abomination.

    It’ll eat your gaskets and digest much else.


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