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I did search for this, and there are some oblique references to the sealant, but the full answer has come up that I can find.

The car is a 1998 Toyota Camry-XLE, 6 cylinder (1MZ-FE) engine with about 178,000 miles. The valve cover gaskets are leaking enough that it's time to replace them. The gaskets are molded rubber that sit in a channel in the head and the valve cover. There are lots of twists and turns in this cover though. I have read online everything from you should always use a sealant, to you should never use sealant, and pretty much everything in between. But what 99% of these never include is the reasons why.

So, should I use a sealant for this gasket change? If so:

  • What sealant is correct so as not to eat the rubber?
  • Where on the gasket should the sealant be applied, only at corners, or over the full length of the gasket?
  • How much sealant should be used?
  • What about the spark plug tubes, should they have a sealant around the rubber rings? Same sealant?
  • What temperature range is the best for the cover gasket sealant in this application?
  • Given the channel (not a flat surface) what the best way to clean out the old sealant without scratching or marring the cover or the head?

Thanks in advance for any help with this!

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  • I'm not a car expert, but... Gaskets that don't require sealant are designed to create a proper seal without additional help, so if sealant is needed, it can often mask an underlying problem. If one of the parts being sealed is warped, it's probably better to fix the warp instead of using sealant. Of course, there are sometimes tradeoffs; my car recently failed its smog check because the intake manifold warped from the heat, and rather than spend a thousand dollars buying a new manifold that might simply warp again, I had it fixed with high-temperature silicone sealant instead.
    – Robert Harvey
    Oct 23, 2017 at 19:17
  • If anything, I would only consider a non-hardening sealant like "Hylomar" or similar. Such goop would potentially mask inperfections. In the end, gaskets with 178k need to be renewed, and most likely fresh gaskets would cure the problem entirely. Proper cleanliness and careful observation of torque pattern and final values are critical.
    – SteveRacer
    Oct 24, 2017 at 3:19

3 Answers 3

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Generally you don't need to use any sealant on this type of gasket, mainly because the gasket is pliable enough and will seal on it's own. If I were going to use any sealant on it, it would be where the rounded part (in the back of this photo) which has a sharp corner:

enter image description here

The reason is, the corner of the gasket is a hard place to seal. Putting a dab of sealant in this spot can help alleviate the threat of leakage. This isn't always needed for any gasket with this same configuration, but it's just easy insurance against leaks if you aren't going to be taking the valve cover gasket off any time soon.

As far as what type of sealant to use, any which is RTV (room temperature vulcanizing) and can withstand oil should work out just fine. The type I'm talking about is like Permatex Ultra Black. It is highly oil resistant and will seal up just peachie.

As a side note, ensure you clean the gasket surface and valve cover really well. I found varnish on the head side of a valve cover I just did which could cause leakage. Cleanliness is next to godliness ... just sayin'. :o)

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  • I have pondered this, is there any issue just saying "ill ATV everything appropriate and be done with it"? If yes then there must be some conditions when gasket must be pure, what would be such conditions?
    – Chris
    Mar 3, 2019 at 2:55
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You don't need a sealent on this gasket. The new gasket will stand much prouder than the flattened gasket you'll be removing, and the WSM doesn't specify sealent anywhere. Torquing the cover down to the correct spec will create a good seal.

Any existing sealant is probably from an older repair where the mechanic tried to seal a leak without removing the cover. Remove it with a non-marring scraper (plastic or similar - not a screwdriver)

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  • I have plastic interior tools with a flat scraping edge that I like to use for this, but because the cover and the head are both hemispherical channels, they don't work well at all.. Maybe use the corners of the flat plastic tool to scrape it out of the channel?
    – cdunn
    Oct 23, 2017 at 21:37
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There is nothing wrong with using a gasket sealant on older cars. Yes the gasket from the manufacturer is fine. But the engine isn't brand new, it's old and may have slightly warped or has imperfections. Using gasket sealant just seals away those imperfections.

You just want to put enough so that you can smear it across the full length of the gasket and on the metal so it covers both sides. Temperature doesn't really matter, most sealants cure over 24hrs.

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  • When i asked about temperature i was thinking of operating temperature more than curing temperature..
    – cdunn
    Oct 24, 2017 at 2:26

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