Leaking Valve Cover - Sc400

[AppleJack]

Hello, I think I've got a leaking valve cover on my SC400. It's on the drivers side.

Is this common for 240,000km?

Is it straight forward to replace (ie. 2-3hours?)

Is it possible for the PCV to have something to do with this?

and known links or pics on what steps to take?

Do I need just the valve cover gasket or are there other seals to replace?

thanks for you help in advance, it's proven to save a lot of money to ask these questions.

(like the starter motor I changed which I'm sure saved $1500!!)

Applejack

[AppleJack]

Me again, and here is an attached image to help visualize my oil leak. thanks.

[mwmorph]

Me again, and here is an attached image to help visualize my oil leak. thanks.

there are gaskets. As far as easy, maybe depends on how the hood area is stuffed/laid out. When ti comes down to it, unbolt the bolts, take off the gasket, put on new gasket, polish those dirty covers a bit and chekc the covers to make sure it's physiocally fine and then reinstall the covers and tighten bolts to specifications(alldata or service manual wil lgive you the proper torque specs). You dont realyl need to do the last step since as long as it;s tight and not insainely tight or loose, it'll be fine, but a service manual is useful as hell anyway.

http://www2.lexpartsonline.com/parts/parts...ket+Set&dp=true

you might need other things too.

Remember, anywhere there is a fluid you need to keep in or out, there will be a gasket between metal on metal surfaces.

How much is it leaking, if it's just a very minor leak, it's just wear and tear and you really dont need to replace the gaskets. The car should be fine. If you are losing oil noticibly and need refills between oil changes, that is casue for replacement.

[AppleJack]

I've taken of the valve cover but I noticed the old gasket had an additional bead of RTV or silicone to help seal in certain areas. I'm pretty sure this was OEM stuff but don't know if I need to replace it when I install the new one. When I asked the parts dept at lexus, they said I only need the new gasket.

Any thoughts on this - especially where the head geometry has sharp corners?

[mwmorph]

The silicone can be found at any decent automotive store and its called silicone gasket sealer or something clsoe depending on brand. It's usally black and has a strong sour smell. Put a bead on both sides of any gasket when installing it.

[AppleJack]

Did it all last night. Cleaned cover and head very nice and made sure to remove old beads completely.

Put the silicone/seal material (black) in the corners. I don't think there is a need when the aluminum head is smooth and flat (no scratches etc).

Need to wait 24 hours for proper cure and we'll see. Is there much pressure in the cover area. I'm assuming its more of a casing for the oil splashing around inside... I don't have a torque wrench so I snugged them up using a 1/4" drive so I wouldn't over do it . .. I'm guessing 20ftlbs max ....

[mwmorph]

you are supposed to put a ring of silicone around the head and another on the valve cover not just a small bead at the corners. You'll want to cover the most surface area with the silicone to prevent anything from getting out or in.

[AppleJack]

Come on? really - that much? hmmm. Well, I've only put the stuff where there were corners or changes in the material on the gasket surface ....

It seems to be ok - but I'm not 100% convinced. I've put about 500 miles on it so far - ranging through various accelerations and speeds ... Time will tell I guess.

Now, is this practice of putting a bead all the way around something that is just a preference -or is it a standard activity in conjunction with a new gasket?

TO BEAD OR NOT TO BEAD ? anyone?

[ko90ls]

i'd say bead! the oil touches the whole gasket not just the corner??? just kinda makes sense to me...? no expert here though.

[jzz30]

no you dont need to bead it! on the flat surface the rubber will seal but on the corners you just need the dab of silicone becasue the rubber gasket cant seal it as well. the it came like that form the factory so keep it that way. you will just be puting in wasted effort if you go back and take everything appart and seal something thats not leaking!

[AppleJack]

OK - good, cause that's all I did.

Funny thing though ... I still smell a tiny bit of oil, but nothing leaking and I don't think it's coming from the the right side that I did the work on already. Is it possible the otherside is now starting to leak? It's more difficult to get a good look so I'm getting a little mirror thingy to check it out. Do these valve covers tend to leak simultaneously or could there be something else causing excessive pressure? (I'll share back the findings once I've gotten and good view for signs of leak)

thanks,

[jzz30]

well if one is leaking then the other side went through the same heat cycles and age so i would guess its safe to say that it could be leaking too.

[AppleJack]

Holy smokes - you're right! bought a mirror for 2 bucks and checked out part of the perimeter of the valve cover on the passenger side - and it's definitely got a tiny leak. I'm surprised they'd both need replacing at the very same time, but I guess they do age the same and more or less need replacing. (and I thought I would get away with only doing the easy driver's side- sigghhhh)

Lesson's learned - when replacing valve cover gasket - JUST DO BOTH.

[jzz30]

i guess its kinda like changing one cap and rotor on one side huh? well great to hear it was that and not something more critical