1999 T&C Minivan Rear Heater Core

Several months ago I replaced all of the rubber coolant/heater hoses on my
1999 Town & Country Limited Minivan. Other than a few being a royal PITA, I
thought it went fairly uneventfully. A day later, I noticed a small drip on
my garage floor located just in front of the rear passenger side wheel. I
suspect this is the rear heater core, and sure enough when I checked the
hose was lightly damp, so I tightened the hose clamp a bit more, but the
leak did not stop. The leak is fairly minor and I have been able to add
about 8 oz of 50/50 mix every month to maintain the proper level on the
coolant recovery tank.

I now suspect that I could have possibly damaged the inlet tube fitting
going into the core since I recall that I was surprised to see that the
inlet tube actually pivoted in the horizontal plane when I replaced that
short rubber connector hose.

Has anyone replaced this hose or the rear heater core before and if so, can
you confirm that the inlet tubes to the rear heater core are supposed to be
soldered in place/stationary? Given the situation, will I need to replace
the core and if so, how difficult is this job, or can I apply a
simpler/cheaper fix (JB Weld, Epoxy, or have the inlet tube re-soldered)?

Lastly, I've always used the standard green ethylene glycol (Prestone or
Peak 2-year change interval) mix in this vehicle. Can I use Zerex G-5
(5-year change interval) coolant in this vehicle like I do in my newer
Chryslers? Doing so would allow me to avoid doing the time consuming flush
and fill during the remaining expected ownership of this vehicle.

Thanks in advance for your thoughts.

Bob

 

You should be able to see from the fluid trail if it's coming from
within the passenger compartment or just at the hose joint.

My recommendation is to disconnect the 2 hoses going to the rear
heater and couple them together, bypassing the core. If the leak goes
away then you know it's the core.

If the core is leaking your best bet is replacing it I think. You can get
a radiator shop to resolder the inlet tubes but their labor would cost what
a new core would. I wouldn't recommend JB Weld on a joint that is
in the passenger compartment, in order to properly apply it anyway your
going to have to take the interior panel off to get at the heater core and
by the time you get that far you might as well replace the core.

Personally I think the 5 year change mix is snake oil and in another 10
years when we see a lot of used cars with rotted-out cooling systems
people will figure that one out. If your asking for advice on jury-rigging
you may as well know that a simple dump and replace of the mix in the
radiator will get about 1/2 of what is in there, and if you do that every
2 years you will likely keep the anti-corrosion additive package adequately
supplied. Lots and lots of people have gone for extended change intervals
with the traditional green stuff mainly due to lackadasical maintainence
and have suffered no ill effects.

Flushing - if done properly (ie: backflushing) - gets rid of sediment
that builds up. Just because you can make an anti-corrosion additive
package last twice as long doesen't mean that sediment isn't still
building up in the system at the same rate. There is always material
loss from the materials (ie: hoses) as well as some oxidization - the
cooling system isn't sealed - even though it may be happening at a
lower rate - that all contributes material that settles out of the system
into the nooks and crannies. I'm not convinced that the G-5 formulation
reduces the rate that this happens at. Getting the chemical package to
last longer is the easy part.

Ted

 

Ted,

Thanks much for your thoughts. By the way, I do realize I could completely
bypass the heater core and eliminate the leak, but would like to retain the
rear heater if possible since winters here in Chicago can be cold. From
brief visual inspection, the leak seems to be coming from outside the
passenger compartment, but as you suggest it will likely need to be opened
up to confirm that. If I go to that trouble, then I may just elect to
replace the heater core completely since it is now going on 10 years old.
If anyone has replaced the rear heater core and can provide advice/comments
on difficulty of that job, it also would be appreciated.

On the G-05, I've been operating thus far on a 4-year and roughly 40K mile
cycle on my other vehicles and have not had any problems yet, so that is why
I asked. For the record, I do the complete Prestone chemical flush (drain
coolant, fill with tap water, add chemical, bring to operating temperature,
then drain), then backflush afterward with a garden hose, then refill with
tap water and bring back up to operating temperature twice to rinse the
chemical, before refilling. The real issue here is time for the vehicle to
cool down between each of these fills/drains, so as you can see it takes
considerable time. Since I do this now with the 2-year stuff too, I was
looking to save half my labor by going to the 4-year cycle with G-05.

To clarify my original question, I want to know if anyone is aware of
anything in the chemical composition of the Zerex G-05 that is incompatible
with the 1999 3.8L engine design (water pump, block, heads, TStat, hoses,
radiator, heater cores, etc.) since the owner's manual specifies the use of
green, 2-year ethylene glycol. Again, thanks for taking time to reply with
your thoughts and suggestions.

Bob

 

Hi Bob if you don't really want to replace the core you can try K&W
block sealer,I am a mechanic that has worked for used car lots for too
many years but this stuff will work better than anything I have tried.
You will need to drain the cooling system and flush with water and
just follow directions on the can. You might have to look around to
find it or "google it" I hope this will help. Ken

 

Ken,

Thanks for the thought, but I am extremely reluctant to use any type of
cooling system sealer/additive. My thinking here is that anything intended
to plug small leaks could only serve to reduce cooling by clogging the same
radiator vanes and engine block/head passages that I have worked hard over
the years to keep flushed and clear.

Bob

Hi Bob if you don't really want to replace the core you can try K&W
block sealer,I am a mechanic that has worked for used car lots for too
many years but this stuff will work better than anything I have tried.
You will need to drain the cooling system and flush with water and
just follow directions on the can. You might have to look around to
find it or "google it" I hope this will help. Ken

 

It should be a lot easier to replace the rear heater core than the front and
I wouldn't hesitate.

I have had the panels in my van off - it's a different year than yours. You
really
want the factory service manual to know where all the hidden screws are.
Alternatively, visit a local pick-a-part wrecking yard and go inspect the
same
year van as yours that has already been torn apart.

You don't need to chemical flush if your regularly changing the coolant.

I have mixed feelings on the flush chemicals. The one time I went to the
trouble to do it I ended up with a block worse off than before. (It hadn't
had a coolant change in at least 10 years) My feeling on it is that if your
regularly maintaining antifreeze then you don't need it, and if you do need
it then likely your going to create a large slough-off of sediment all at
once
which will plug block metering passages.

The original rule of thumb was that any American vehicle with an older
copper/brass radiator and heater core, soldered together,
should use old-style green ethlyne glycol for greatest protection against
material loss
on the solder. Original HOAT coolants (ie: Zerex G-05) did have some
additives that protect copper and tin/lead solder, but not as much as the
green
stuff contained.

Use of Dexcool in these cars is known to plug heater cores, both Ford and
Chrysler
had a lot of problems with this when Dexcool (OAT) came out as OAT
coolants rapidly corrode the solder. Dexcool in particular is known to turn
corrosive in the presense of air, and is known to be damaging to many
rubber seal materials - it should NEVER be used in a car that didn't have
it as factory fill.

The story going around is that GM got environmental credits from the Feds
for using OAT coolants, and so they didn't give a rat's-ass about what
everyone else was using or how bad their own crappy coolant would be
in other manufacturer's cars.

Older Japanese cars are also known to be safe with green coolant, regardless
of
what their factory fill was.

However, these days the original HOAT coolants have been
reformulated with proprietary trade-secret chemicals to produce the newer
"universal style" HOAT. In other words, the Zerex G-05 coolant of 6 years
ago is not the same chemical as the Zerex G-05 of today that is marked
"Universal" There simply isn't enough ancedotal evidence that today's
Universal
HOAT (G-05 or equivalent) is bad in older cars because these haven't
been on the market long enough. So in answer to your question - nobody
really knows. Zerex almost certainly will tell you that their Universal
G-05 will be safe. But how long has it been on the market in it's current
formulation?

Green coolant is held by many to be damaging to plastic radiators.

Green coolant is also more corrosive to aluminum radiator and heater
cores and to aluminum engine parts.

However, like the Universal HOAT, there's now Universal green stuff
on the market that has -also- been reformulated with trade-secret
chemicals that are not supposed to be as corrosive to aluminum as
before.

Newer American and Japanese cars use aluminum radiators and heater cores.
They
are safe for HOAT coolants (ie: Zerex G-O5) as a general rule.

There are a variety of European and Japanese coolants
that are factory fill in their respective models (ie: BMW uses a blue
coolant) these
should NEVER be used in any models other than what they shipped in. The
Japanese
cars that these coolants come in are as a general rule safe for HOAT
coolants. Not
so for the European cars, which may or may not be, depending on the model.
Worse
from the European side is that there have been a number of changes from year
to
year in the proprietary cooants, making some not even compatible with each
other
for topping off.

As a general rule, only HOAT and original green are safe in a 50/50 mix
with hard tap water. None of the specialty Japanese and European
coolants OR the OAT coolants should be mixed with anything other than
distilled water.

Different coolant types should NEVER be mixed. You must completely
flush to switch from, for example, specialty Japanese to G-05, or from green
to HOAT.


Ted

 

Ted,
I'm a big proponent of HOAT/G-05. Where did you learn that HOAT has
been reformulated? Can you provide links to any articles?

Also I have not seen any Zerex references to it being universal - that
doesn't mean there aren't any - I just haven't seen any. On this page of
their site: http://www.valvoline.com/zerex/automaker.asp
they say "There is no 'one size fits all' chemistry that is approved for
use in all vehicles. Don't take chances—use Zerex AutoMaker Approved
Chemistry" - that's above the pictures of their 3 antifreeze products -
traditional green, G-05 and DexCool™. And on this page:
http://www.valvoline.com/pages/products/product_detail.asp?product=10
I don't see any suggestion of universal use, though I did put it in my
wife's '99 Buick about 3 years ago with no ill effects so far.

On this page:
http://www.valvoline.com/carcare/articleviewer.asp?pg=vcc20051101ac&cccid=2&scccid=1

"Perhaps one of the most important aspects to look for when next
shopping for antifreeze/coolant is approval from the maker of your car.
Currently, there is no 'one size fits all' solution that is approved for
use in newer cars. And filling your cooling system with the wrong
solution may result in serious adverse effects.

"Products marked APPROVED have been subjected to years of field and lab
testing by your car's manufacturer and are certain to provide the best
performance and protection. Also, use of these products will ensure your
car's warranty remains intact. The same cannot be said for using
non-approved products, which may end up causing more problems than they
solve. Some quality antifreeze/coolant producers even print the makes
that have approved their products for use. This is always the best way
to go."

 

Ted,

As always, you are a wealth of information. Thanks. Based on your
response, you appear to be suggesting that I replace the rear core (thanks
for the idea of visiting a salvage yard to "learn") and then stick with the
green or go to the universal green stuff and just reduce my flush interval
to reduce labor/time for the operation. I can accept that as an alternative
I had not considered.

I will comment though on your line that HOAT coolant should never be mixed
with tap water. This is pretty much an impossible requirement if you use
tap to back flush, since you can NEVER get all of this out before you refill
with coolant and distilled (like I do). I actually do my last rinse after
flushing with distilled to improve the mix percentage of distilled, but this
is still not perfect.

Also, I will say that even when I chemically flush and then back flush every
two years, I get a good deal of brackish, brown water out of the system
before it runs clear again. I assume this is normal, but this is why I have
done it regularly at 2 year intervals. I can see the value with my own
eyes.

Lastly, I'll add that I've heard and read so much negative press on DexCool
that I have never ever consider using it.

Thanks again. Now for some good weather and a weekend to take this on.

Bob

 

Do you have an air compressor? You can get a cheap one from
Harbor Freight for $80. When I flush my van, after rinsing with
tap water I use an air blow gun and flush with compressed air. THAT
does get most everything out.

Fortunately where I live we have extremely soft water - so soft, in
fact that the water bureau has to put a chemical in it to harden it up
a bit - otherwise it leaches an unacceptably high amount of lead out
of copper sweat joints and brass fixtures.

If your seeing brown water in the initial flush BEFORE you are putting
the chemical flush in, then I would consider that abnormal. I've not seen
brown water out of any cooling system in any of the cars I've owned when I
flushed
them unless the cooling system had been neglected. I use green stuff with
tap water, my vehicles are not as new as yours.

It's standard-issue for GM. Of course, GM also has the battery terminals on
the side too. I guess they just like being different.

Ted

 

Ted,

Yes, I have a compressor. I never thought of using it for this purpose
though. I guess that you must remove one of the heater hoses and attach it
there to get that to drain out. I'll give it a try next time around.
Thanks again for the ideas.

By the way, the rear leak turned out to be a bad connector hose. No matter
how tight I tried to tighten the hose clamp, it never stopped the slight
drip, so I cut new 5/8" heater hoses and made them slightly longer this time
around, then just replaced them and re-used the same 4 hose clamps. For
now, anyway, the dripping has stopped. The good news is that the heater
core and the quick connections to it look fine ... the leak was on the other
side of the hose connection.

Bob

 

Yo - Ted - you there?

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

 

Yes, this news server I'm using isn't always, though.

Ted