1fz spark plug loosening

1973Guppie

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Hi Folks, thought I would post up with an issue I am having on my personal truck. 1996 FZJ80. Plug #4 keeps loosening for some reason. It seems about every 5k miles I get a rough idle and yup each time the plug is loosened in the block. A few turns of snugging it up solves the problem. I am taking off on a long trip into the wilderness here soon solo with the kids and wondering if I should be concerned about this. In the past I have only snugged plugs up by feel. I put 20# on the #5 plug today (FSM torque is 14# I believe) and am hoping it will stay put. I have tried changing the plug with no change in symptoms. Has anyone had an issue like this? I am considering buying one of those rethreading kits to have in case of emergency. Thanks for your opinions, experiences.

Noah
 
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Are you using a new gasket (washer) with the plug when you retighten it (or a new plug with new washer)?? Threads clean? Use anti-seize?
 
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Sounds like someone over tightened that plug at some point and the threads are stripped. You could chase the threads with a tap. Or try putting teflon tape on the plug. Or install a heli-coil.
 

1973Guppie

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Are you using a new gasket (washer) with the plug when you retighten it (or a new plug with new washer)?? Threads clean? Use anti-seize?
yes, yes, no
 

1973Guppie

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Sounds like someone over tightened that plug at some point and the threads are stripped. You could chase the threads with a tap. Or try putting teflon tape on the plug. Or install a heli-coil.
not likely as I have owned it for a long time and have never overtightened it. Threads seems fine as it take fsm torque but later comes loose. Like I said before, new plug makes no difference.
 
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I put 20# on the #5 plug today (FSM torque is 14# I believe) and am hoping it will stay put.
There was the overtightening ... aluminium vs steel .. and a running motor with a loose plug stresses the remaining plug holding threads as well

I would helicoil or even better Würth time sert the threads ...
 

1973Guppie

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There was the overtightening ... aluminium vs steel .. and a running motor with a loose plug stresses the remaining plug holding threads as well

I would helicoil or even better Würth time sert the threads ...
that was today, I put another few pounds on it, so no in the past it was not overtightened.
 

mudgudgeon

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In the past I have only snugged plugs up by feel.

so no in the past it was not overtightened.

When was the last time you had biceps calibrated?
The old strongarm torque wrench can vary a lot with mood, enthusiasm, frustration etc

If it's coming loose and a new plug doesn't fix the problem, the problem is in the head.
If everything is clean, then sounds like the threads are cooked.
 
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FWIW, this can't be reliably repaired with the head on. Anything you screw into the hand will find its way into the block.
 

1973Guppie

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When was the last time you had biceps calibrated?
The old strongarm torque wrench can vary a lot with mood, enthusiasm, frustration etc

If it's coming loose and a new plug doesn't fix the problem, the problem is in the head.
If everything is clean, then sounds like the threads are cooked.
you might be on to something, I am having some spinal problems and need to have surgery, have lost some strength in my arms in the past 6 months.
 

1973Guppie

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FWIW, this can't be reliably repaired with the head on. Anything you screw into the hand will find its way into the block.
It actually can. Others have done it. You can use an insert.
 
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Could put some loctite 55 “thread floss” on it for some extra hold. It sucks at doing what it’s supposed to, but it’s good for keeping bolts from rattling out.

Never tried it on a plug tho.
 

clx16

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I would be putting in a new sleeve/insert. I have had to do it on another Toyota before as it shot a plug out on me, far away from home. When it goes you might find a kit to fix it but you won't know exactly how deap the insert needs to be nor will you be able to be picky about which kit you use unless you research first. You also will need to source a plug and wire and whatever else gets melted by that hot repeating puff of mixed air and fuel coming out of your stripped plug hole.

I got mine fixed enough in an AutoZone parking lot which happened to have a kit, a plug and a coil for my vehicle, also a good magnetic plug holder so i could use the kit and a bag of bearing grease so i could catch at least some of the metal shards. I ended up making it home and having to remove the insert i put in as it was too long and i needed to get the new one in with red locktight. I had to be creative to get the insert out that was incorrect.

When you do it at home on your schedule, you get to cut and tap, then rig a hose to vacuum out all the shards of aluminum out of the piston, you can put in the sleeve/insert that is the right length and that you prefer, and you are not rushed and can perform all the appropriate steps while reading the instructions, watch videos etc.

Look on YouTube for "the torque test" channel and "project farm" channel as they have both recently tested these inserts.

It is my opinion your threads will keep getting worse and i also believe inserts/sleeves are as strong if not stronger than original.

There Are some US domestic vehicles that end up having to have all plug holes done and it is an actual improvement over the factory head design which shoots plugs to the point that is has made the procedure almost preventative maintenance on those vehicles...
 

1973Guppie

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I would be putting in a new sleeve/insert. I have had to do it on another Toyota before as it shot a plug out on me, far away from home. When it goes you might find a kit to fix it but you won't know exactly how deap the insert needs to be nor will you be able to be picky about which kit you use unless you research first. You also will need to source a plug and wire and whatever else gets melted by that hot repeating puff of mixed air and fuel coming out of your stripped plug hole.

I got mine fixed enough in an AutoZone parking lot which happened to have a kit, a plug and a coil for my vehicle, also a good magnetic plug holder so i could use the kit and a bag of bearing grease so i could catch at least some of the metal shards. I ended up making it home and having to remove the insert i put in as it was too long and i needed to get the new one in with red locktight. I had to be creative to get the insert out that was incorrect.

When you do it at home on your schedule, you get to cut and tap, then rig a hose to vacuum out all the shards of aluminum out of the piston, you can put in the sleeve/insert that is the right length and that you prefer, and you are not rushed and can perform all the appropriate steps while reading the instructions, watch videos etc.

Look on YouTube for "the torque test" channel and "project farm" channel as they have both recently tested these inserts.

It is my opinion your threads will keep getting worse and i also believe inserts/sleeves are as strong if not stronger than original.

There Are some US domestic vehicles that end up having to have all plug holes done and it is an actual improvement over the factory head design which shoots plugs to the point that is has made the procedure almost preventative maintenance on those vehicles...

thx for your comments, agreed, it it loosens again I will be going this route.......
 

mudgudgeon

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you might be on to something, I am having some spinal problems and need to have surgery, have lost some strength in my arms in the past 6 months.

Sorry about your back troubles.

I know from my own experience, torquing stuff by feel can be wildly inaccurate, especially at low torque settings
 

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