Coolant leak between head and block

Discussion in 'Engine Topic' started by scrap--metal, Jul 7, 2019.

  1. Bandit723

    Bandit723 Veteran Member

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    From GM Techlink March 2004:



    Cooling System Seal Tabs What’s made of ground-up ginger root, almond shells and binder? And causes confusion in auto service departments?

    Some people call them coolant pellets, but the proper name is Cooling System Seal Tabs. And we hope to clear up some misunderstandings about them

    How They Work
    Seal tabs are dissolved in the engine coolant and the resulting fibres circulate through the cooling system. At a microscopic level, the tabs break down into irregular, long, thin fibres. When a small leak or seepage occurs, the coolant carries the fibres into the opening, where they cluster up and jam together. (Think of logs and branches in a beaver dam.) This mechanism is very effective at stopping leaks. Any fibres that make it to the surface will crust over and enhance the seal.

    This sealing method is useful only for small-scale leaks and seepage, and tends to work best in conditions where the surrounding parts aren’t moving. The seals tend to break down in areas between metals that are expanding and contracting with temperature changes, for instance.

    A Secondary Benefit
    The traditional green-colored coolant, used until DEXCOOL[​IMG] was introduced in 1996, contained silicates, which deposit on cooling system surfaces. The tiny fibres from the seal tabs acted as scouring pads, removing silicate deposits from the water pump seal faces, which contributed to longer water pump seal life.

    Side Effects of Seal Tabs
    In addition to the benefits of sealing small leaks and scrubbing silicates from water pump seals, seal tabs also have some side effects.

    After awhile, a brown, dirty-looking stain may form on translucent coolant bottles. Residue may form on the backside of the radiator cap. And deposits that resemble rust may be found in the cooling system.

    These are not problems, in the sense that they cause no physical harm. But their appearance can be alarming, especially on a new vehicle. Both customers and well-intentioned technicians can be misled by these deposits.

    Another side effect comes from overuse. When seal tabs are used in the prescribed amounts, they will not cause restrictions or plugging in an otherwise properly operating cooling system.

    But, if a little is good, a lot must be better. Wrong!! Overuse can lead to plugging, especially in the relatively small tubes used in heater cores.

    Some History
    There was a time when seal tabs were installed in every new vehicle, at the factory, to account for the inevitable small leaks that occur in castings, joints, and so on. By the mid ‘90s, manufacturing and machining techniques had improved to the point where the seal tabs were no longer needed on a universal basis.

    With the introduction of long-life coolant, silicate deposits were no longer a concern, so the scrubbing action from the seal tab fibres was no longer needed.

    TIP: GM plants, as well as other manufacturers, still occasionally use seal tabs to address specific concerns.

    Today’s Recommendations
    In short, GM no longer endorses universal use of seal tabs. Procedures in SI have been specifically written to discourage their use in most cases.

    When a condition appears in which seal tabs may be beneficial, a specific bulletin is released, describing their proper use. One such bulletin is Customer Satisfaction Program 03034, dated 7/7/03. This applies to specific 3.8L engines only, and is in effect until July 31, 2005.

    TIP: After performing the procedure in the bulletin, be sure to install a recall identification label to the vehicle to indicate that the seal tabs have been installed.

    TIP: If seal tabs were installed in a vehicle at the factory, it’s OK that the proper amount of tabs be installed if the coolant must be drained and replaced.

    What’s a Recommended Dose?
    TIP: Use this information only when instructed to do so by bulletin or SI procedure.

    The proper number of Cooling System Seal Tabs depends on the capacity of the vehicle’s cooling system. Use between 1 and 1 1/2 grams of tabs per liter of cooling system capacity.

    TIP: Cooling System Seal Tabs are packaged in two sizes.12378254 Small tabs (4 grams each) 5 tabs per package
    3634621 Large tabs (10 grams each) 6 tabs per package
     
  2. scrap--metal

    scrap--metal Veteran Member

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    Thanks for the recommendations, guys. At this point, my leak is more than a weep. I'd call it a steady drip.

    Way to be a Debbie Downer! Negative sarcasm isn't going to fix anything, especially not on my car.

    What makes your advice more valuable than someone who recommends not using cooling tabs? I never said that the cooling tabs were "wrong", but I will say that it's not my first choice to fix the problem. There's more than one way to skin a cat.

    I used Zecol Mendtite (another coolant sealer) in my '76 Monte Carlo's 305 when it started smoking some, per the recommendation of a mechanic friend, and that seemed to help the problem. I ran the same engine, radiator, heater core, etc. for a couple more years until I sold the car. It never caused any problems that I'm aware of. Regardless, that engine was not worth taking apart for diagnostics or re-work. I feel like my Camaro engine is worthy of more of my time.

    I'm hoping to pull the head off this weekend.
     
  3. scrap--metal

    scrap--metal Veteran Member

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    Mike, thanks for the informative post on the "cooling system seal tabs". I like details like that...

    I'm still planning to rip the head off, but I'll be thinking about the coolant tabs for future issues. Hopefully it won't come to that on this engine.
     
  4. Bandit723

    Bandit723 Veteran Member

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    Hoping you find the root cause of the leak and are able to fix it. Good luck!
     
  5. scrap--metal

    scrap--metal Veteran Member

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    I just wanted to follow up on this thread from last summer. I replaced the driver's side head gasket last fall, only a week before the car went into storage. I used the same Fel-Pro head gasket that leaked the first time around (#7310). I've got close to 1000 miles on it this year, and there's no more coolant leak. I didn't want to call it "fixed" until I had some more miles on it to prove it. I left the passenger side head alone (if it ain't broke, don't fix it).

    Thanks to everyone who's helped with advice on cam selection and then this coolant leak. If it weren't for all of the helpful members here, I never would've felt comfortable tearing into an engine to replace a cam and bearings.

    Now I need to deal with my oil pan. Just about a month ago, it started leaving a drop of oil on the pavement near the rear of the oil pan. I checked and some of the pan bolts were loosening up a bit. I'm going to try removing them 1 by 1 and reinstalling them with Permatex 2. Hopefully that seals the threads and prevents them from loosening. It's a 1 piece Felpro oil pan gasket with the sleeves around each bolt hole.
     
  6. Coadster32

    Coadster32 Veteran Member Lifetime Gold Member

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    Thank you for updating this thread. Glad to see you're on the positive side of this.
     
  7. Rich Schmidt

    Rich Schmidt Veteran Member

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    When I bought my GMPP aluminum big block heads they came with instructions to use GM stop leak additive in the cooling system. Apparently it is a common problem. BTW,my GM heads were made by Edelbrock.
     
  8. 350camaro

    350camaro Veteran Member

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    I have heard that Ford did the same thing with the 7.3 and 6.0 powerstrokes
     
  9. kenny77

    kenny77 Veteran Member Lifetime Gold Member

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    When I bought my new ZZ 383 short block, the new High Lift Vortecs I also bought shipped in a different crate. In that crate were the new head bolts, and a package of those tabs.
     

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