Got leaky coolant or poor performance? Maybe your head is cracked!
From an email from Joe Molnar:
On the cracked head issue,
Chrysler used steel (3ea) tappered threaded plugs in top of the head to
seal off the water jacket after it was cast. The cracks usually develped
from where the plugs were screwed in. A bulliten was issued to dealers
to let them know a kit was avaiable to install aluminum pugs inplace of
the steel ones. This stopped the cracking problem. I dont have the
bulliten number anymore, but I had this done a few years ago from where
I purchsed the car. If you can find a good service man, he can find the
info and retrofit youre head if not already done so. On the timing belt
issue when you by a new belt (gates # T206) make sure the belt is made
in Italy and not the U.S. or England. there is a big differance in
strenght and reliability. The box will be marked where it was made. The
reason for the belt problems is vibration on the long run of the belt.
To compensate for this, Chrysler retarded the exhaust cam 6 degress to
move the vibration on the belt to the short run between the two cam
sprockets. So you can imagine there is some power to be gained by
re-degree of the exhaust cam alone, but the belt problem would get
From Dave Stocker
Fellow Spirit R/T owners:
Anyone out there have any experience with the spark plug core plug =
replacement? For those who don't know, the steel spark plug wells leak =
and should be replaced with aluminum wells.
Not quite. These are the casting core plugs, similar to the press-in "freeze"
plugs which close up the holes where the casting sand was dumped out of the
water jacket after casting - except these are pipe-threaded. The head is
aluminum. The original core plugs located between the spark plugs in the
valley of the head were steel, which expands at a different rate and caused
a problem with cracking the heads. These need to be replaced with aluminum
to avoid cracking the head at these three locations. Their only relation
to the spark plug holes is that they're located nearby, there's no functional
(Did you verify that steel plugs were still in place?)
I had my car in to the dealer at least three times because of =
oil/coolant in the wells between the time the TSB (91164375) was issued =
Which? Oil or coolant? Oil is from leaky valve cover gaskets. Coolant is
from a head cracked due to the steel core plugs.
which was not fixed. Then 3k miles after the 7/70 expired, a plug broke =
off in the #1 cylinder and wiped out the piston and the head. (The =
I can't imagine any way that the core plug issue could have caused the
spark plug tip to break off.
The dealer fixed it ($4500! and it took seven weeks!), but didn't lift a =
I don't suppose you saved the damaged head? I could use a spare.
replies came back from a couple of mechanics that the plug broke because =
of the well problem -- but they didn't add any detail to support that =
2) Anyone familiar enough with this core plug problem to have an opinion =
on if it _really_ could have caused my plug to break? Looks to me like =
they're directly related -- but I'm not a mechanic.
See above - the core plug goes to the water jacket (where the engine coolant
flows), and the spark plug goes into the cylinder. There's no path from
the core plug to the tip of the spark plug, unless things are so badly
cracked (or head gasket blown) such that a path exists from the water jacket
to the cylinder - in which case you would have experienced massive overheating
from hot exhaust entering the cooling system. Even then, I don't think hot
coolant would have caused the spark plug tip to crack.
I still think that the spark plug mfg. is the one to approach on this, FWIW.
The good news is that my car runs great. For better or for worse, I'm =
very attached to it!
Good luck! -
David Wright 65 Plymouth Belvedere II 4-door 273-2
email@example.com 74 Dodge Challenger Rallye 360-4
"Still plays with cars" 92 Dodge Daytona IROC R/T 2.2 Turbo III
Go back to the Spirit R/T FAQ!