By on March 22, 2019


TTAC commentator slavuta writes:

Something came into my head related to break-in period and time of purchase of the car. These days, modern engines often don’t have actual gaskets; the gaskets are formed from a chemical compound spread on one surface and pressed-on with another.

As everything liquid becomes hard or nearly hard, it requires a curing period. From the time an engine is assembled to that time when it starts seeing real usage could pass months or even a year+. Of course, the engine sees some usage from testing and from the car being moved around during shipment.

But let’s say you buy this car in the middle of a harsh winter. We know that materials shrink and expand as temperatures goes down and up. Do you think buying a car during summer gives more curing and settling time to these gaskets vs buying in the winter, especially in the areas where winters are really cold? Yes, engine becomes hot during operation but many materials seem to get more elastic with heat and more hard and fragile with cold. Ever tried to leave even an empty garden hose outside in the cold? Your thoughts – are there any break-in advantages from buying in the summer?

Sajeev answers:

So yeah, I cannot find concrete (as it were) examples of manufacturers using this liquid-to-solid gasket technology. While vehicles regularly use glorified rubber o-rings (i.e. molded rubber) in place of traditional gaskets (that are not head or exhaust manifold gaskets), clearly I lack the Google-Fu to verify your vantage point.

Don’t get me wrong: machine these metal parts perfectly and traditional gaskets aren’t needed. Just ask the timeless, gasket-less (sort of) Citroen 2CV.

Also don’t get me wrong: anaerobic gasket maker can be a lifesaver, with few pitfalls. Are they used often from the factory? Maybe!

And when applicable, the parts cured long before a new vehicle’s first taste of lot rot and/or your first monthly payment. According to Permatex’s snazzy graph (here), their anaerobic gasket maker has an 80-percent cure rate after 100 hours (4-ish days) on aluminum parts. Sure, just-in-time manufacturing means parts won’t sit around gathering dust, but components aren’t leaving the powertrain factory and meeting an assembled car body in much less than 4 days. 

They are gonna spend at least a day on/near the assembly line. Plus, odds are good that the OEM-specified gasket makers have a cure rate quicker than off-the-shelf Permatex. So my thoughts?

It doesn’t matter what time of year, what amount of heat cycling, etc., as the gaskets cured well before you said “can I test drive it?” 

Bonus!  A Piston Slap Nugget of Wisdom: 

Let’s not forget the real hero of automotive seals/glues: the structural adhesive.  They’ve been in play since at least the early 1980s (found during my research of the Ford Fox Platform) keeping unibody platforms tighter and lighter, and we’ve never heard of cars literally falling apart from poor structural glue…have we?

[Image: Shutterstock user Fusionstudio]

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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22 Comments on “Piston Slap: Fear the Anaerobic Gasket Maker?...”

  • avatar

    Many components that use gasket maker in the factory have been given ample time to cure. Most components are produced in a different factory than where the vehicle is assembled and tested. After assembled, these components sit in a staging warehouse and then are shipped to the assembly plant and then sit in another staging area until they are ready to be inserted in the vehicle assembly. The gasket compound in these components have plenty of time to cure.

    I cant speak for other brands but the GM “silicon” that comes in a large caulking tube is really really good stuff. GM uses this gasket maker all over its lineup from the factory.

    I re-geared my truck to 4.56’s and used this stuff to seal up the diffs. I drove it immediately after I finished the job, and pulled the cover to changed the fluid again at 500 miles. Both times the compound had less than 30 minutes to cure. It has been over 45k and I have not had any leaks or wet spots.

  • avatar

    I think your premise is off base entirely, at least among North American made automobiles. American manufacturing engineers with automotive backgrounds are practically allergic to any kind of applied liquid, be it gasket, oil, grease, etc.

    A gasket maker liquid is easily avoided by using an actual gasket, but since the same MEs are also allergic to loose pieces the molded rubber gaskets that self-retain are pre-installed from the subcomponent supplier.

    Any liquid application that cannot be avoided in final assembly would be done with automation to ensure complete, measurable, and repeatable application without interference of human error. As such any gasket curing would be “baked into” the automation process, although I’m sure that ambient conditions in the manufacturing environment between the time of application and shipping out would be more than adequate.

    I wish I had so little to worry about.

  • avatar

    That looks similar to Toyota’s FIPG (Form In Place Gasket) that they’ve been using since at least the ’90s (the transmission pans on our Previas used it).

    And yes, perfectly machine surfaces don’t always require gaskets. I can remember GM V8 engines from the ’60s, like Pontiac and Oldsmobile V8s, that didn’t use any gaskets between the heads and exhaust manifolds.

  • avatar

    These sealants have come a long way and are pretty good .

    It’s the average repair dufus who creates problems by using it incorrectly or far more often, way too much of it .

    FWIW, those gasketless exhaust manifolds were terrible ~ in less than ten years most required a gasket added to stop the endless leaks caused by thermal changes during normal operation .

    I grew to hate this design after doing so many repairs on them .


  • avatar

    I find the question and commentary here very educational; I’ve been aware of the structural adhesives used but honestly thought the use of Gasket Maker was only used where replacement gaskets weren’t available… honestly never thought about its use in modern engine manufacturing. After all, this could be one reason why newer engines are more reliable (though I question whether or not it was used in a certain ’96 3.8L V6 I had in a Camaro whose engine seized due to cylinder corrosion 8 years later (and 165,000 miles. Then again, that engine saw some hard, HARD use in its first four years.)

  • avatar

    It isn’t possible to plan ahead for every automotive repair. Those of us that grew up with experience in pre-OBD cars generally learned a few things:

    A feeling of ‘crab walking’ is a bad tire/rim/axle.

    The difference between transmission and power steering whine.

    Letting go of the steering wheel once in a while will assess the adjustment of the steering system.

    The differences between white, black and blue smokes.

    Just buy a good car and drive it without fear. Your chosen emotional/love partner needs more repair than a late model car. Cars drive themselves to 100k now— as in they’re still new if the owner hasn’t parked by feel or poured coffee into the upholstery.

    I had a friend who drank a lot— he had to get rid of a car before it was paid-off because projectile vomit got INTO THE DASH.

    Don’t do that.

    And don’t worry about gaskets. The mechanicals will be worn before the gaskets pop. I haven’t had a leaky gasket in anything built after 1998 that was daily driven— hobby cars can and do leak.

  • avatar

    Air cooled German cars, VW and Porsche, have used a sealant between the engine case pieces (2 or 3) since the dawn of time. In ancient times products similar to Permatex No. 2 or 3 were what was available. That worked for some time, but eventually the sealant hardened with heat cycles and would leak. Later, products such as Curil T were developed and worked for the engine lifetime.
    As others have mentioned, sealants are used by OEMs for places such as oil pans, differential covers, engine (timing) covers and so on.
    When I was doing repair/overhaul work full time I had many different sealers on hand. As in the link to Permatex in the OP, it is important to use the appropriate sealer for the application. Most silicone based sealers will be dissolved by gasoline, for example.
    A big advance around 1980 were the Oxygen Sensor Safe silicone sealers. They work much better than the older “regular” silicone sealers.
    Contrary to advice on the Permatex “Gasketing Mistakes” page, I have had great results adding sealers to gaskets, O-rings, and cooling hose connections. When faced with doing it the “wrong” way or replacing a expensive engine block, cylinder head, or other part I will use a sealer. Its important to use an appropriate product and not too much.
    The “Ultra”, Oxygen Sensor Safe, silicones work well where coolant hoses attach to aluminum parts. Small corrosion pits are sealed and the silicone remains flexible to deal with hot and cold. Also the hoses are much easier to remove the next time since coolant is less likely to get in between the hose and aluminum causing corrosion.

  • avatar

    Never commented before, but the subject matter is what I do for a living. I work for a major OEM and am an engineer that works with the RTV sealant suppliers that supply to Honda and GM, among others.

    First, most of the major components that use a sealant instead of a rubber gasket use RTV – Room Temperature Vulcanized silicone. This cures from exposure to moisture in the air. This is different from Anaerobic that cures from a lack of air exposure (so the excess that squeezes out of a joint remains liquid). The advantage of the RTV vs. Anaerobic is that the RTV has better elongation properties that can handle more motion between joints. Anaerobics are more common sealing cam-caps or as a thread-sealant.

    All that said, the RTV applied in an engine plant generally has skinned over where it is exposed/squeezed out of the joint within the first 10-25 minutes depending on the RTV brand/grade. So the RTV begins to have sealing capability very early on because the RTV is only liquid in the gooey center (that’s a technical term :) ). As a rule of thumb, RTVs will fully cure within 7 days of assembly.

    One of the comments above mentions the amount of time it takes and engine to go from the end of line at the engine plant to the vehicle plant. It is really unlikely that an RTV would not be fully cured by the end of 7 days. If there is any banking of engines whatsoever between the end of the engine line and shipment to the vehicle plant, there is little to no chance the RTV has not fully cured. But, if I were to speculate on what time of year the RTV likes, it would be when there is more humidity in the air, since the moisture in the air needed for proper curing. The cure will happen slower at times of year where the air is relatively dry.

  • avatar
    Eric the Red

    Never thought a lot about gaskets vs sealant. But my 2015 F150 2.7L Ecoboost keeps eating the oil pan sealant and leaking. They replace the oil pan when they fix the leak so I am now on my 3rd oil pan at 40k miles. I have asked my Dealer if I need to put new oil pan and sealant under the 20k maintenance schedule! They don’t use gaskets. They apply sealant between the pan and the engine. Service Department says they don’t usually have problems but I am “special”.

    • 0 avatar

      Force the issue with Ford if it keeps happening and see if they can give you an extended engine warranty or replace the engine. Sounds like you might have an engine with block porosity issues.

    • 0 avatar

      Some unsolicited input: The Ford 2.7L ecoboost uses a plastic oil pan, and to my knowledge is the only plastic oil pan in the industry that is sealed with RTV. Not sure how/why Ford is doing this successfully (though just one example, clearly Eric the Red’s F-150 doesn’t support success). When they remove the pan to fix the leak they are likely putting a new pan on because the plastic pan will be damaged when they pry it off (this is usually the case with stamped steel pans too). Since you are getting a new pan each time it probably is the engine side.
      It is particularly difficult to reseal an oil pan on an engine in vehicle because it is very difficult to keep the sealing surface on the engine side of the joint free from oil as oil drips down during the repair. RTV doesn’t like to stick to oil so this is a big challenge for the mechanic. I know for a fact that Ford actually has a special “primer” that they offer in service to help the RTV bond – if you dig through their Motorcraft website you’ll find part # ZC-31-B which is a tub of wipes that is designed to help the RTV bond better to the metal. It is promoted as a cleaner degreaser, but the real benefit is that it acts as a primer. The dealer may not be remembering (or be instructed) to use this despite is availability. I don’t work for Ford, but I’ve done my homework to know what they are doing! The link below should take you right there.

      It may be this is the cause of the recurring leak, but often times the oil pan gets blamed for leaks that happen higher up on the engine that are at close proximity – such as the rear crankshaft seal. The retainer that houses the rear seal on this engine is also sealed to the block with RTV. If that is leaking it might look like an oil pan leak because the oil might leak down onto the oil pan joint. Mechanics don’t typically jump to replace rear seals because of all the work involved to disconnect the engine and transmission, but it might be the real culprit. Also, this is two-piece block and there could be leakage between the upper and lower parts of the engine that are also sealed with RTV. But hopefully this is all trivia you won’t need and your third oil pan is the charm!

      • 0 avatar


        Thanks for commenting and for your expertise. My dad wrote specs for structural adhesive use on aircraft – one thing he has successfully drilled into my head is to do proper surface prep (e.g. wipe with isopropyl) for any structural adhesive repairs. It sounds like the same idea applies to RTV sealant.

      • 0 avatar

        Belerich’s comment is a great testimonial for BEVs.

        • 0 avatar

          Points to blue oval on Eric’s truck – “here’s your problem…”
          TEASING John, relax! Lol.

          Eric, you could put some oil-compatible UV dye in the crankcase – then if the leak does come back at any point, you could see directly/immediately if Belerich is onto something with the rear seal hypothesis.

      • 0 avatar

        Agreed. If it is the oil pan seal, it probably isn’t possible to fix it with the engine sitting the correct side up. Unfortunately when you seal the pan in the car it’s not possible otherwise.

  • avatar

    Yes back in the 90’s we definitely had structural adhesive failures. The fantastic plastic door skins on F-Bodies would be hanging from their door handles after particularly cold nights in places like MN and MT or anywhere it got well below zero.

    As far as the various sealants the majority of them have in service times of under 24hrs so no worry about uncured product by the time it gets to the dealer.

  • avatar

    RTV gaskets has been common practice since the ’90s. I remember visiting a major manufacturer’s engine factory in 1998 and watching a robot arm precisely apply a bead of permatex to a valve cover and then plop it right in place. The rest of the engine accoutrements were added, and an hour or so later the engine slid into place on the dyno, did a five-minute test on a carousel, and got crated to send to the end vehicle’s assembly plant.

    RTV is amazing stuff, and I don’t doubt its ability to cure and hold no matter what time of year it was assembled.

  • avatar
    SCE to AUX

    One of my favorite FIP gasket applications is in automatic transmission pans. The old cork gaskets ALWAYS leaked.

  • avatar

    Thanks, Sajeev. You inspired me to find this

    Now, looking at different engines diagrams today, I see that indeed, all use gaskets for valves and head but oil pans and chain covers may not have them. But then, these are not as important.

  • avatar

    Working in shops there were always goopers, and non-goopers. Myself, I’d always go with a dry gasket on clean surfaces if I had a choice.

    The problem with the goobers, err, goopers, is they all tended to use too damn much. You’d pull an engine apart and find balls of goop that had ended up in cooling systems, oil passages, everywhere.

    The question I never could seem to get answered was how long to wait between applying a line of goop and assembling the part. Some GENERAL guidelines, based on the type of goop, materials, temp, etc. would be helpful.

    • 0 avatar

      I would always assemble immediately after dispensing RTV. You really want to assemble for the RTV skins over – and depending upon the specific grade and the relatively humidity, that could begin as quickly as 5 minutes. The real issue with balls of goop is applying too much. A good rule of thumb is to stay below 1/4″ bead diameter. This doesn’t seem like much, but if the joint is designed properly that will cover pretty much the whole width of the flange when you assemble. You’ve already correctly alluded to the fact that more is not necessarily better! For aluminum pans with a chamfer on the inside/oil side edge of the flange, place the bead as close to the chamfer as possible. You actually want RTV on that chamfer because that is where the RTV does most of the sealing. If it is a stamped oil pan, place it close to the inner/oil side radius for the same affect. If there is no chamfer or radius on the inner edge then I would place the RTV in the center of the flange to prevent too much falling into the oil.

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