Spark Plug vacuum leak

[Timothy]

I have been desperately trying to find the vacuum leak in my car for months now. Well I think I found it. When I spray starter fluid down into the spark plug wells the engine revive. You can actually see the starting fluid being sucked up at the threads of the spark plug. Having recently replaced the spark plugs a month ago I thought maybe I just needed to torque them down a bit more. Manual says 22 foot pounds.

Anyway, I retorqued therm and it's still a problem. The plugs did come with a crush washer.

I have read the spark plugs wells can leak, but you would get oil on your spark plug, which I do not.

Before I run out and buy better spark plugs does anyone have any ideas?

[rickbz28]

Did the old washers come out with the old plugs?

[Timothy]

Ohh, great question. I have no idea, and at the time I didn't even think twice about it.

Let me get in there with a flashlight and see if there is a washer sitting in the spark plug well.

[ryanprins13]

Most likely dirt under the washer.
Second most likely double washer.
Third is you crossthreaded it, lol.

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[Timothy]

I don't think that is a washer. But it is very rusty at the bottom of the well. Maybe a good cleaning will take care of it?

Take a look at the pic. That doesn't look like a washer does it. It also doesn't move. IMG_0575.jpg

[Timothy]

Great suggestions you guys. I'm going to find a way to clean these up a bit.

[Timothy]

First round of cleaning made it better, but not perfect. Would a little RTV to help the seal be a dumb idea?

[ryanprins13]

Rtv wont hold the pressure back.
Doesnt look like a washer to me, but hard to tell from the photo. You should be able to tell fairly quickly with a good flashlight and/or a pick.
Wire wheel on a dremel if you have one to clean that up. Or sandpaper.

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[WmWatt]

Don't let any dirt fall into the cylinder chamber.

[Timothy]

New spark plug made no difference.

I'll post a better picture. Maybe it's a little better.

Now I'm picking away at it with a pick and cleaning up Witt a shop vac. IMG_0576.jpg

[bhazard]

Helicoil

[Timothy]

Helicoil

How would rethreading the spark plug hole help. The threads seem to be fine. It's just not vacuum sealing.

[firebush357]

Are you putting Anti Seize on your threads when installing your plugs?

Dirty Threads will cause you to achieve the target torque quicker than clean threads due to extra friction, basically this will cause a lower clamping force on the washer. On the other hand, adding any kind of lubricant such as anti seize will increase your clamping force due to the fact that there is less friction and you will not reach target torque until a higher angle.

I would try putting a good coat of anti seize on the threads and running it down and then back out again and then clean the threads of the plugs to get the grit and dirt out then re apply the anti seize and torque it down to the target torque to see if that helps any.

Keep in mind that if you over torque the plugs you will lower the spring effect of the threads therefore lowering the clamping force the next time you install them and you also run the chance of breaking something.

[Timothy]

Are you putting Anti Seize on your threads when installing your plugs?

Dirty Threads will cause you to achieve the target torque quicker than clean threads due to extra friction, basically this will cause a lower clamping force on the washer. On the other hand, adding any kind of lubricant such as anti seize will increase your clamping force due to the fact that there is less friction and you will not reach target torque until a higher angle.

I would try putting a good coat of anti seize on the threads and running it down and then back out again and then clean the threads of the plugs to get the grit and dirt out then re apply the anti seize and torque it down to the target torque to see if that helps any.

Keep in mind that if you over torque the plugs you will lower the spring effect of the threads therefore lowering the clamping force the next time you install them and you also run the chance of breaking something.

Thanks for helping out. Yes I am using antinseize. I will try your method now and report back shortly.

[firebush357]

How would rethreading the spark plug hole help. The threads seem to be fine. It's just not vacuum sealing.

There is a chance that the threads could be damaged, are all of the plugs leaking air or just 1?