Piston Slap: Fear the Anaerobic Gasket Maker?

Sajeev Mehta
by Sajeev Mehta
piston slap fear the anaerobic gasket maker

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 sajeev@thetruthaboutcars.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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  • Slavuta Slavuta on Mar 22, 2019

    Thanks, Sajeev. You inspired me to find this https://www.quora.com/Can-a-4-stroke-gasoline-car-engine-be-built-without-a-head-gasket-One-cast-or-fused-If-so-would-the-added-compression-ability-be-significant 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.

  • Wadenelson Wadenelson on Mar 23, 2019

    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.

    • Belerich Belerich on Mar 28, 2019

      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.

  • Tassos No car "needs" a manual today.No Driver "needs" a manual today.Let's use the english language precisely.Only some Drivers WANT a manual.And most people who make a lot of noise about how good manuals are, then go out and buy another AUTOMATIC.Auto Journalists are always very fond of manuals.Actual CAR BUYERS in the US BUY 99% automatics, regardless of what they CLAIM.30 years ago, automatics were lousy and inefficient and had too few gears and manuals had better MPG and cost $1-2k less to buy a manual vs an auto car.Today all these advantages have gone up in smoke.
  • Tassos I have driven exclusively manuals in my own cars for the first 30-40 years of my driving history. They were usually very affordable, fuel efficient simple vehicles with front wheel drive. Their manuals sucked (in the case of a 1983 GM vehicle I bought new) or were perfect (in my two 5-sp manual Hondas).After 2005, I started driving excellent 5 and 7 speed automatics in my own cars, which were NOT available in the US market with manuals.With today's outstanding automatics, which are also MORE, not LESS, fuel efficient than any manual, your question becomes MEANINGLESS.Because NO CAR "needs" a manual.Only some DRIVERS "WANT", NOT "NEED", a manual.Let us use language PRECISELY.
  • 3SpeedAutomatic And this too shall pass.....Ford went thru this when the model T was introduced. It took the moving assembly line to make real money. As time progressed, it got refined, eventually moving to the Model A. Same kind of hiccups with fuel injection, 4 speed automatic, Firestone tires, dashboards with no radio knobs, etc, etc, etc. Same thing with EVs. Yep, a fire or two in the parking lot, espresso time at the charging stations, other issues yet to be encountered, just give it time. 🚗🚗🚗
  • Art Vandelay 2025 Camaro and Challenger
  • Mike Beranek Any car whose engine makes less than 300 ft-lbs of torque.
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