Rad Repair 98 Intrepid 2.7

I seem to have a leak Front Passenger side, drips on the horn, sometimes
does sometimes doesn't. Minimum loss of fluid, no overheating to speak of.
Checked hoses etc.
Question is : I understand it is a plastic radiator (!!!) can this be fixed
with Prestone or similar stop leak. It seems to have worked but I have a 4
hr drive next week and would appreciate anyones experience with these
plastic rads.

 

Aluminum radiator CORE with plastic tanks. Standard method of
manufacture these days, unfortunately.

can this be fixed

The inevitable can be DELAYED with stop-leak, but I don't trust what
stop-leak does to the rest of the system. Bars-Leaks brand is pretty
innocuous, but even it probably reduces the heat exchange capacity of
the system a bit. Some of the more aggressive stop-leak compounds are
also known as "heater-core plugger compounds" for good reason.


The plastic/aluminum tanks actually hold up remarkably well. My wife has
(knock wood....) almost 250,000 miles on her '93 LH on the original
radiator. It has a pinhole leak right in the top of one of the tanks,
which I've just been keeping my eye on. Its so tiny that it doesn't even
drip, just makes a crusty spot where the coolant evaporates. The danger
is that once you have a crack in the plastic, the pressure cycles might
make it grow very fast and very suddenly. If you can see the leak and
are fairly sure its a pinhole type leak and not a crack with visible
extent, then I wouldn't worry much about a short 4-hour trip and back.
Carry a jug of water to be on the safe side.

 

Have you tried a dab of Right Stuff?

 

Hmmm... no. But that could work- with the system cold and no pressure,
just "grind" it into the pinhole with a thumb.

 

The leak has got worse, its down the seam on the passenger side, leaves
puddles at each stop!!
Im taking it to a RAd shop tomorrow!!
K

 

If practical, for a pinhole leak take a piece of wire that is longer than
from
the hole to the nearest radiator opening. (Obviously out of the vehicle.)

Strip the insulation off the wire and throw the wire away.

With a SMALL drill, enlarge the pinhole. Then feed the insulation through
the
enlarged pinhole and out opening. Now put a 'tack' into the insulation
tube.
Smear a bunch of goo you want to use to seal with on the underside of the
tack and carefully PULL the tack into the radiator till the spike sticks out
the hole. (The hole you drilled MUST be large enough for the tack with
the insulation over the spike to fit the hole!) Let it set/cure.

When it's almost set, but not 'hard set' clip off the external spike.

The advantage of this is you now have a 'compression' fix against radiator
pressure, not a patch that can be 'blown off' by radiator pressure.

Although I'm leery of putting a 'tack' in my radiator...

If possible, I'm much more comfortable with enlarging the hole to where
I can use the same trick to feed a small 'bolt' with a big washer on it,
even
rubber washers if possible, from the inside of the radiator and once it's in
place then put a washer and nut on the outside with even more goo to
'pinch' the radiator tank body. Then when I'm satisfied, I much up the
exposed threads of the bolt so there's no way the nut could come loose.

 

Not that it will fix the current problem, but for the future...
After fixing the radiator on an old car of mine, the old time radiator
repair specialist told me that on old cars he always puts a 7 psi radiator
cap on (regardless of what's called for by the factory) to lower the
pressure stresses on the old systems. As long as there's an overflow tank on
the system, it won't result in any net loss of fluid, but will lower the
likelihood of further problems...
To get the right 7 pound cap you'll need to go to a "real" auto parts store
(like a NAPA) -- many places will just look your car up in their computer
and hand you *only* the factory spec cap...

 

I understand where you're coming from on that, but I've got to question
the ultimate wisdom of that practice. I guess the idea is to put a
ceiling on the max. system pressure for moderate temporary pressure
spikes. My concern would be a situation of moderate to serious
overheating in which the 15 psi cap may (not guaranteed, but may) at
least prevent flash boiling and reduce the chance of engine damage,
whereas in the same situation, the 7 pound cap will possibly totally let
loose in a flash boiling suddenly leaving critical overheated parts that
are accepting even more heat from even hotter other parts unsurrounded
by liquid coolant.

I guess there are different but real increases in risks either way, but
I would think the right way is to do preventive maintenance (use the
right coolant, change it before it on a realistic scehdule) and replace
any and all weak parts (certainly old hoses, any radiator showing signs
of age, etc.).

The 7 psi cap seems like a bandaid to me. The primary goal is to
protect the engine - not to protect weak parts in the coolant system
that need to be replaced. Again - the 15 psi cap may prevent flash
boiling (and engine damage) in a situation in which the 7 psi cap would not.

IMO...

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

I am sure that you all saw that post a few weeks ago that contained a
link to a picture of radiator that had blown out part of it's tank. I
would be hesitant repairing the tank after seeing that picture. I
don't every remember every seeing a brass tanked radiator doing that.

-KM

 

I don't think there's ANY way that a Chrysler LH will run with less than
12-14 psi of cooling system pressure. These cars, like most modern cars,
operate at significantly higher temperatures than older cars for better
fuel efficiency, lower emissions, and (although it isn't intuitive) less
wear. You can run a '49 Plymouth with NO radiator cap and at most a
small waft of steam will come out the radiator neck. If you just *idle*
an LH car to get it up to operating temperature without a cap, coolant
will boil in the cylinder heads and send a geyser out the neck. Heck,
even my '66 Dodge *needs* a 12-14 psi cap to avoid pushing too much
coolant into the overflow tank, and that's just with a 180-degree
thermostat, not the 195 or 210 thermostats like modern engines use. Even
if you can run the car at lower pressure, you can be sure that you are
having "microboiling" going on in the heads creating steam pockets that
result in hot-spots, and cavitation that erodes metal from the inside of
the cooling passages. Lowering cooling system pressure is ONLY a
reasonable option if you do something like convert to one of the
waterless coolants like Evans NPG. And then you give up some heat
transfer capacity in the process.

 

No, I've never seen a brass tank radiator fail quite like that (big
chunk gone out of the tank). HOWEVER, I definitely HAVE seen a brass
tank radiator fail by having the tank blow completely off the core at
the solder joint. Different failure mechanism, but just as sudden and
just as complete. :-/

Mechanical design and materials selections always have tradeoffs, and
even though my first reaction also was "Ewww! PLASTIC?!?!?" I've come to
realize that "plastic" tank radiators aren't so horrible after all.
Harder to fix when broken, but they do have some advantages.

 

That's that flash boiling I was talking about. That just means
temperatures are rising well above the boiling point (the low boiling
point that accompanies little or no pressure), after which, once that
water flash boiled, there's *nothing* to moderate the temperatures
soaking thru from the even hotter metal immediately surrounding the
combustion chamber.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

a lower rating pressure cap will result in higher engine temp
the pressure spec is directly related to heat dissipation thru the raditor
get a new raditor and quit screwwing around a engine rebuild is too much money