Leaky Spark Plugs
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Freshman User
Joined: Oct 2003
Posts: 30
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Leaky Spark Plugs
89' F-150, 4.9L Inline 6, 136,000 miles.
I changed my spark plugs over the weekend and noticed the plugs in cylinders 5 and 6 were not tight. I had a difficult time getting new plugs to seat tightly. When the motor runs, I can hear air leaking around the spark plugs in the problematic cylinders.
What is my best option to restore the cylinder threads? Has anybody run with leaky spark plugs for an extended duration? In other words, how long do I have before these plugs blow out of the head?
Thank you!
I changed my spark plugs over the weekend and noticed the plugs in cylinders 5 and 6 were not tight. I had a difficult time getting new plugs to seat tightly. When the motor runs, I can hear air leaking around the spark plugs in the problematic cylinders.
What is my best option to restore the cylinder threads? Has anybody run with leaky spark plugs for an extended duration? In other words, how long do I have before these plugs blow out of the head?
Thank you!
Post Fiend
Joined: Oct 2003
Posts: 6,214
Likes: 13
From: New Jersey
Re: Leaky Spark Plugs
What is my best option to restore the cylinder threads? Has anybody run with leaky spark plugs for an extended duration? In other words, how long do I have before these plugs blow out of the head?
http://www.barnhillbolt.com/acb26/he...&MenuCode=MAIN
How to install:
http://www.emhart.com/products/helicoil/install.htm
If they are aluminum heads, another method is to remove all the plugs, thorougly clean out the threads from both sides, and fill in the sparkplug holes with a tig welder.
Both methods work fine.
Posting Guru
Joined: Sep 1999
Posts: 2,297
Likes: 1
From: Indiana
xg325
If they have not been crossthreaded, you can clean the spark plug holes with a spark plug hole tap. Where the plugs were loose, combustion material got in the exposed threads making it tight to seat the plugs on down in the hole.
You can buy these at about any automotive store. I have one that is double ended, one is a larger thread for older motors and the other side is 14mm which is what you need. This will not damage the threads in any way, it will make it easier to change the plugs from here on out.
The head on the 300 6 is cast iron, so its tough.
If they have not been crossthreaded, you can clean the spark plug holes with a spark plug hole tap. Where the plugs were loose, combustion material got in the exposed threads making it tight to seat the plugs on down in the hole.
You can buy these at about any automotive store. I have one that is double ended, one is a larger thread for older motors and the other side is 14mm which is what you need. This will not damage the threads in any way, it will make it easier to change the plugs from here on out.
The head on the 300 6 is cast iron, so its tough.
Last edited by Superdave; Mar 3, 2004 at 10:53 PM.
