2001 Caravan 3.8L - Seized Spark Plug

Have a 2001 Grand Caravan that was at the shop today (3.8L engine w/82K
miles.) The Service Manager indicated they could not do a tune-up due
to the fact that one of the plugs on the front bank was seized in the
head and he was afraid to strip the head out.

Any idea how prevalent a seized plug is in this engine and what the
success is of trying to get them out without tearing the threads out of
the head?

 

It isn't uncommon if you fail to use anti-sieze on the threads when you
install them. Tearing out the threads isn't all that big of a deal as
you can put in a helicoil.


Matt

 

Those platinum plugs stay in for so long, this is probably your first
replacement/????.. you can soak them with a penetrating oil, I recommend
rust penetrate from Chrysler, it works great, soak them over night and try
to remove them cold.

Glenn Beasley
Chrysler Tech

 

I believe the plugs were replaced by the same dealer at ~ 30K miles. So
what can you offer on how often this might happen and how offen the
penetrating oil is successful (what are the odds that the Dodge dealer
gets it out without charging me to replace a head?)?

 

See the previous remark on heli-coils. And a heli-coil might not even
be necessary.

You take the plug out, using whatever violence is necessary. This
will tear up the threads. Now you put a thread-cleaner through the
hole. In my experience, this will normally end up with threads that
work well enough to get compression, which is all you really need.

If this isn't good enough, you re-thread the hole with a bigger tap,
and put in an insert called a heli-coil. In Nomen Nescio's ideal
world of $150,000 Neons, all aluminum heads would have heli-coils
installed at the factory.

It's really hard to imagine taking out a seized plug causing so much
damage that a heli-coil can't fix it. If the service writer seems to
be uncomfortable with this idea, something is really wrong.

 

Joe Pfeiffer wrote:

Yes, it may be time to switch to another shop.

Matt

 

See E mail

 

!00k platinum plugs in that engine, replaced at that mileage unless there is
a problem, soak the plugs over nite, remove them from a cold engine and they
should pop out, anytime you remove hot steel from hot aluminum metal,
problems like this happen, that goes with changing your engine oil also,
steel drain plug + aluminum pan= damaged threads when hot.

 

Really? I've heard just the opposite. AL expands at a rate higher than
steel. Steel plug inside of aluminum will get looser as the temp goes up.


Matt

 

hey glenn
i found out a neat thing that happens with the rust pen. from mopar
when you soak something with it then heat up the area, when the bubbles show
themselfs around the bolt/nut it ready to come out easy

 

I replaced the original platinum plugs in our '96 T&C at some mileage over
100K. They came out with completely reasonable effort. The plug boots were
more difficult to remove than the plugs. Another interesting fact: even
though some of the gaps were about 2X the factory setting, the car still ran
great. There was no change that I could detect in performance or gas mileage
before and after.

Ken