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I have a 2005 highlander that has around 140k miles. It is running great, and I've had to do minimal work on it besides routine maintenance. I could see driving it for at least another 5 years.

I got an oil change recently and the mechanic said he noticed some oil leaking where the valve cover gasket is. I took a look myself and do see some sticky sludge all around the circumference of the engine.

It's not due for any major maintenance for a while, so it's not like I can just add this work on to a spark plug replacement or something that I'd be doing anyway.

Would you replace the valve cover gasket? Or just keep an eye on how the car is running/keep an eye on the oil level intermittently to see if the leak is getting worse?
 

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Replace it. Are you planning to do it on your own? If so replace the spark plugs and pcv valve also. Parts are cheap. Oil leak from valve cover can cause miss-fire and reduce the life of your ignition coils and O2 sensors. If you are doing it yourself I can share parts I’ve used.
 

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Discussion Starter #3
I wouldn't do this work myself... not sure if that would affect the decision about whether or not to have it done.
 

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If you're keeping the car for 5 more years, then Yes do it or have it done.

Sent from my SM-G970U using Tapatalk
 

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It’s labor intensive so if you do it yourself it will be $20 for gasket and RTV. I did gasket PCV valve, Air intake gasket, Throttle body and MAS cleaning. Not sure how much a Mechanic will charge you. I’m guessing 400-800.
 

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Depends upon where it is leaking and how much. You need to look at it and make the call.
What I think:
If is is seeping into the spark plug wells then it can cause misfire and kill the coil pack and needs replacement if torquing the screws does not work.
If it is entirely external then the problems can be:
In the extreme, it can become a fire hazard from any heat or spark source.
1) oil leaking onto exhaust manifold causing odor and toxic gas creation near your cabin air intake
2) oil leaking onto wiring and connectors can degrade signals.
3). Oil can degrade hoses and rubber
4). Nobody likes oil spots on the driveway
5). Makes it much dirtier for a mechanic to work on your car, which affects their attitude and may make it easier to get dirt where it shouldn’t go.

Oil seepage can be caused by deterioration of the gaskets and sealant.
However, a key place to look is the PCV system. If the PCV system is not working properly, the crank case, including under the valve covers, may be under positive pressure which will force oil past gaskets and seals. Check your PCV system to make sure it is clean and working properly. Replace the PCV valve and clean the hoses, including the top vent hose.

Also, make sure that the valve cover screws are torqued to specification. I found mine loose.
 

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Since your having it done ask how much it will be to get PCV valve, Air intake gasket, MAS cleaning, Throttle body cleaning, and spark plugs replaced. Maybe you can wait for your next major tune up. If I have the money, I would get it done as soon as possible. To prevent major damages in the long run that will cost much more. Post the cost please. It makes the DIY guys feel good about how much they saved - Thanks
 

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Also all these parts are in the same area that needs to come off during valve cover gasket replacement, so I would think it will cost less to get it all done at once.
 

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2003 Highlander
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2003 V6 AWD 342k miles. Original owner.
Just a thought here...how about just going around and checking valve cover bolts for tightness before embarking on gasket replacement? I haven't done this myself on my HL but the effort on my Audi paid off. That car's valve cover is notorious for leakage. Sure enough the area that was oozing had 3-4 loose bolts. A quick twist and no more leak. Just a thought....
BTW- my HL appears to have some slight wetness around the front valve cover. Maybe I'll try my own advice. Naw, it's probably spillage from the last oil change. Hehe. Anyway, my rule of thumb : if it ain't dripping on the garage floor, it's not a leak. Best of luck, Haya...
 

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I would save it for when you have a larger repair such as a timing belt\water pump replacement. That way you aren't paying for all that labor just for a valve cover gasket. You have to pull the valve covers off to change the water pump anyway, so they'll get new gaskets then.
 

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I would save it for when you have a larger repair such as a timing belt\water pump replacement. That way you aren't paying for all that labor just for a valve cover gasket. You have to pull the valve covers off to change the water pump anyway, so they'll get new gaskets then.
Strange. On my 2005 HL 3.3L V6 I didn’t have to touch the valve cover to replace the water pump.
 

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Maybe it's different, Mine has a piece of sheet metal that covers the water pump but is behind the cam sprockets. I had to take the valve covers off to get a wrench on the camshafts to take the sprockets off. Or maybe I did a bunch of extra work when there was a better way...
 
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