4.0 L Core/Freeze Plugs
 

Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
Cherokee with brass plugs due to corrosion of the original steel ones.
The Cherokee ran great for about two months, and then, under a moment
of hard acceleration, one of the new plugs blew out. Fortunately the
engine was not damaged, and I again replaced the one that blew. The
folks at NAPA said that this can be a common problem when replacing
core plugs if the cooling system is not bled properly. My question to
you masters out there is this: is this the probable cause, and if so,
what is the best way to ensure that this will not occur again? I may
have saved $600, but the tow cost $100!

Thank you all so very much!

Re: 4.0 L Core/Freeze Plugs
 

Quattro GR4 did pass the time by typing:
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!

After running for two months you shouldn't have any air left in the 4.0 block.
It's a closed system that vents air and sucks back in extra coolant from the
overflow bottle. It's more likely the plug didn't sit correctly and worked
it's way out. Not all those holes are perfectly round. Wouldn't be the first
time a plug popped out on someone.

Hard acceleration doesn't increase coolant pressure except directly between the
pump and thermostat. Overheating/boiling can but that pops the radiator safety valve.

--
DougW

Re: 4.0 L Core/Freeze Plugs
 

Quattro GR4 did pass the time by typing:
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!

After running for two months you shouldn't have any air left in the 4.0 block.
It's a closed system that vents air and sucks back in extra coolant from the
overflow bottle. It's more likely the plug didn't sit correctly and worked
it's way out. Not all those holes are perfectly round. Wouldn't be the first
time a plug popped out on someone.

Hard acceleration doesn't increase coolant pressure except directly between the
pump and thermostat. Overheating/boiling can but that pops the radiator safety valve.

--
DougW

Re: 4.0 L Core/Freeze Plugs
 

Quattro GR4 did pass the time by typing:
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!

After running for two months you shouldn't have any air left in the 4.0 block.
It's a closed system that vents air and sucks back in extra coolant from the
overflow bottle. It's more likely the plug didn't sit correctly and worked
it's way out. Not all those holes are perfectly round. Wouldn't be the first
time a plug popped out on someone.

Hard acceleration doesn't increase coolant pressure except directly between the
pump and thermostat. Overheating/boiling can but that pops the radiator safety valve.

--
DougW

Re: 4.0 L Core/Freeze Plugs
 

Which one keeps blowing out? Is it the rear freeze plug?

--
Billy_Ray@fuseSPAM.net (Remove the SPAM)
2002 WJ Brilliant Black Crystal Pearl Coat
Helping is why we are all here on RAMJ+W, or should be.
..
"Quattro GR4" <coffeeguy@cox.net> wrote in message
news:1135303326.142133.147010@g49g2000cwa.googlegr oups.com...
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!
>

Re: 4.0 L Core/Freeze Plugs
 

Which one keeps blowing out? Is it the rear freeze plug?

--
Billy_Ray@fuseSPAM.net (Remove the SPAM)
2002 WJ Brilliant Black Crystal Pearl Coat
Helping is why we are all here on RAMJ+W, or should be.
..
"Quattro GR4" <coffeeguy@cox.net> wrote in message
news:1135303326.142133.147010@g49g2000cwa.googlegr oups.com...
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!
>

Re: 4.0 L Core/Freeze Plugs
 

Which one keeps blowing out? Is it the rear freeze plug?

--
Billy_Ray@fuseSPAM.net (Remove the SPAM)
2002 WJ Brilliant Black Crystal Pearl Coat
Helping is why we are all here on RAMJ+W, or should be.
..
"Quattro GR4" <coffeeguy@cox.net> wrote in message
news:1135303326.142133.147010@g49g2000cwa.googlegr oups.com...
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!
>

Re: 4.0 L Core/Freeze Plugs
 

Nope.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Quattro GR4 wrote:
>
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!

Re: 4.0 L Core/Freeze Plugs
 

Nope.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Quattro GR4 wrote:
>
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!

Re: 4.0 L Core/Freeze Plugs
 

Nope.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Quattro GR4 wrote:
>
> Hello - I recently replaced all five 2" core plugs on my 1997 4.0L
> Cherokee with brass plugs due to corrosion of the original steel ones.
> The Cherokee ran great for about two months, and then, under a moment
> of hard acceleration, one of the new plugs blew out. Fortunately the
> engine was not damaged, and I again replaced the one that blew. The
> folks at NAPA said that this can be a common problem when replacing
> core plugs if the cooling system is not bled properly. My question to
> you masters out there is this: is this the probable cause, and if so,
> what is the best way to ensure that this will not occur again? I may
> have saved $600, but the tow cost $100!
>
> Thank you all so very much!