Sparkplug replacement

infiniti
g35

#1

The mechanic wants to replace the valve cover gaskets because they are seeping oil but there are no drips or noticeable oil loss and it costs $330. Should we do it?


#2

Someone can correct me, but I think it’s only important that it doesn’t leak so much that the oil level doesn’t drop too low between oil changes. Also, oil leaking onto your asphalt driveway is never a good thing. If it’s just seeping, I probably wouldn’t be too concerned but that’s just my opinion.


#3

I can think of 3 good reasons to get it fixed.

  1. the leak will not get smaller only larger
  2. oil on hot exhaust manifolds can be really, really bad.
  3. $330 is not a bad price (I’m guessing this is a v6)

#4

Per the previous 2 comments. @PvtPublic is right, it won’t get better but seeping oil can stink. But as per @jries007 if it isn’t dripping on the ground, you aren’t losing much oil at all.

Yes this should be done but it doesn’t have to be done immediately.


#5

If the oil is leaking into the recesses where the spark plugs are (is that the reason for the title you gave your post?), you should have the gaskets replaced.


#6

What the mechanic is telling you is not incorrect, however whether you want to get the valvecover gasket replaced is dependent on a large number of variables. If you do a lot of highway driving, like commuting, it may be worth it. If you only do local driving, it may note be, as long as it isn’t causing any kind of a problem. Mine seeps a bit (240,000 miles on the engine) and I’ve had the new gasket in the garage for six months, and on my engine it’s a “5-minute job”, but I’m retired now and don’t drive much. So I probably won’t bother until I get bored some day.

The thing to realize is that this seepage is normal and does not cause any further damage to anything. What’s happening is that after the oil lubricates your lifters and camshaft(s) (if you have an overhead cam engine) it simply runs down “galleys” and through return paths into the oil pan. Normal pressure (from the crankcase) under the valvecover tends to push a bit of it past long-compressed gaskets. It can cause premature deterioration of the rubber on the boots at the ends of the COPs (at the sparkplugs), but that does not manifest itself in any damaging way other than perhaps the occasional need for new COPs. I haven’t had a problem at all in mine.

In summary, if you drive a lot of miles, especially highway miles, it’s worth it. If you, like me, don’t drive all that many miles, it may not be.


#7

I’d leave it alone for now. The first step here is to review your maintenance schedule to see if your vehicle requires a timing belt service, and if it does, then when is it due next.

In most cases, the valve cover gaskets are replaced at that time because the valve cover has to be removed anyway. You will save a lot of money getting it done at that time, along with various other oil seals and the water pump.


#8

Here is another one…


#9

Another what?


#10

Heading on thread is about sparkplugs but question is valve cover gaskets. Are they related ?


#11

In some vehicles it is.


#12

Volvo, perhaps you should reread the OP’s original question (above).


#13

The part about the spark plugs is not mentioned in the question, I suspect oil is leaking into the spark plug tubes.


#14

That was my guess too.


#15

I was thinking the same thing, but a little oil around the spark plugs won’t hurt anything. Oil is a dielectric.


#16

If the valve cover gaskets are just slightly leaking, it might be possible to stop the leak by re-torquing the valve cover bolts. That wouldn’t cost much. Just make sure the shop tightens them only to the manufacturer’s spec only, not tighter. Otherwise you’ll risk turning an inexpensive problem into a considerably more expensive one. Could work. If done properly, worth a try imo.

I should add I’ve never been able to completely stop a valve cover leak by just a re-torquing. But I have been able to completely them by removing the valve covers and gaskets and just doing a clean-up and reinstalling the existing gaskets. On the Corolla, valve cover leaks are often not the gasket itself leaking, but the rtv sealant used in conjunction with the gasket has broken down. There’s a couple spots near the ends of the camshafts where the gasket has to be fortified with a dab of rtv, and that’s usually where the leak occurs. Whether that applies to OP’s car, don’t know.


#17

If there’s an oil leak into the plugs well, it is an indication of bad valve cover gasket.


#18

Be careful retorquing the bolts. Some manufacturers use shoulder bolts to precisely control the valvecover gasket compression. I’ve run into this before. Trying to tweak these down could result in having to remove a broken shoulder bolt. Shoulder bolts break right at the shoulder, and removing the threaded part then involves drilling, using an “easy out”, and if it’s stuck maybe even drilling and tapping. It’s all doable, but more work than you may want to end up with.


#19

The torque should be about 10 ft/lbs. The issue here is that it is a V6 and that may require removing the intake manifold to retorque the bolts. That’s what makes a $40 cover rail gasket job a $300 cover rail gasket job.


#20

Have you seen the Jeep Grand Cherokee’s V6 nowadays? They put 3 of the 6 spark plugs under the intake manifold! O_o