Need to rethread a plug hole from a blown plug
Thread Starter
Seasoned Member
Joined: Mar 2011
Posts: 349
Likes: 4
From: Lexington, KY
Year: 1996
Model: Cherokee
Engine: 4.0
Need to rethread a plug hole from a blown plug
Bought an '11 Vic with the 4.6L back in June and a few months back I tried to change out the plugs. All came out ok except for cyl 4 which only cranked out 1/4 turn. Had a shop take it out and they said they had to redo the threads. I've seen videos where you can remove a stuck plug by drilling into it somehow, but because this was in the 4 position and hard to get to I'm guessing they just power cranked it out. Not sure but I'm guessing those threads are compromised now.
Well, this past weekend that same plug blew out of cyl 4. Inspection reveals a coil and boot jammed up underneath the fuel rail and a plug that I fished out without any turning. When I go to install a new plug it just sits on top of the threads and turns without going in. So I guess what's happened is that the plug rotated most of the way out but when it got to the last couple threads the compression blew it out the rest of the way, and that it's just the top few threads in the hole that are damaged. Inspection of the plug reveals that most of the threads are intact except for the 2-3 that are closest to the element.
So my question is...should I try to fix this myself or just take it to a shop? Some kind of tap tool would probably fix it, but since it's the beginning threads that are boogered it'd probably have to start from the inside of the cylinder. I really don't have a clue as to how to approach this.
Well, this past weekend that same plug blew out of cyl 4. Inspection reveals a coil and boot jammed up underneath the fuel rail and a plug that I fished out without any turning. When I go to install a new plug it just sits on top of the threads and turns without going in. So I guess what's happened is that the plug rotated most of the way out but when it got to the last couple threads the compression blew it out the rest of the way, and that it's just the top few threads in the hole that are damaged. Inspection of the plug reveals that most of the threads are intact except for the 2-3 that are closest to the element.
So my question is...should I try to fix this myself or just take it to a shop? Some kind of tap tool would probably fix it, but since it's the beginning threads that are boogered it'd probably have to start from the inside of the cylinder. I really don't have a clue as to how to approach this.
Senior Member
Joined: May 2017
Posts: 645
Likes: 34
Model: Cherokee
Needs helicoiled. Personally I’m not a fan . I’ve done them and I’ve came across them on different engines . More times than you want to hear the first time you go to pull that plug in the future it will pull the heli coil right back out . If it were me I’d find a used head or reconditioned one if I were going to keep it for any time at all.
Thread Starter
Seasoned Member
Joined: Mar 2011
Posts: 349
Likes: 4
From: Lexington, KY
Year: 1996
Model: Cherokee
Engine: 4.0
Ok that's not easy to read but I'm glad to have a better picture of things now. Does this other system I've heard of called Time-Sert have any better repair rate? Their insert is solid.
So to make this repair last as long as it can, what kind of plug should I put in there that'll last the longest? Would it be unadvised to run a long life plug in cyl 4 and regular OEM in the other 7?
So to make this repair last as long as it can, what kind of plug should I put in there that'll last the longest? Would it be unadvised to run a long life plug in cyl 4 and regular OEM in the other 7?
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
We used to maintain the local Budget truck fleet. when the vans would blow the plugs out like that, we towed them down to budget in Phoenix. They are a special type of PITA from what I'm told. The plug change interval was 96,000 miles BTW.
Member
Joined: Mar 2017
Posts: 108
Likes: 0
From: State Center Iowa
Year: 1997
Model: Cherokee(XJ)
Engine: 4.0L I6
Ok that's not easy to read but I'm glad to have a better picture of things now. Does this other system I've heard of called Time-Sert have any better repair rate? Their insert is solid.
So to make this repair last as long as it can, what kind of plug should I put in there that'll last the longest? Would it be unadvised to run a long life plug in cyl 4 and regular OEM in the other 7?
So to make this repair last as long as it can, what kind of plug should I put in there that'll last the longest? Would it be unadvised to run a long life plug in cyl 4 and regular OEM in the other 7?
CF Veteran
Joined: Dec 2015
Posts: 3,038
Likes: 338
From: PA
Year: 1997
Model: Cherokee
Engine: 4.0L
The 4.6 has been known for blowing plugs 3 and 4. Ive heard of the 6.8 doing it as well. If its not something youve done before, take it to a shop. There are different tools for this. OTC probably makes one. Here is another. Ive never done it myself tho.
Thread Starter
Seasoned Member
Joined: Mar 2011
Posts: 349
Likes: 4
From: Lexington, KY
Year: 1996
Model: Cherokee
Engine: 4.0
Thanks fb. Considering I didn't have any experience with this I took it to a shop and they put in a time-sert looking solid insert they said was made by heli coil.
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