97 Intrepid overheating

I have a 97 Intripid, 3.5Litre (well 2 of them actually, and the other is
working good other than the check engine light) that is overheating. This
past winter it overheated one day and limped into an out of town garage.
They replaced the t'Stat and said I should not drive it as it appears to be
leaking antifreeze somewhere. Contrary to their recommendation I drove it
home (an hour away) with no problem. A few days later I went to my regular
garage and they checked it out and said the water pump was leaking and
subsequently replaced it.

It worked fine for a while then one day started pushing the antifreeze out
the overflow. I changed the t'stat again and drove it some more. Drove
it some more and then (weeks later) it happened again. Topped it back up
and drove it back to my garage and they checked things out again, but could
not find anything wrong. They let me search their electronic service
manuals and found a notice about having to bleed the system. I did this
and it worked fine again (for a while). Yesterday the problem started
re-occuring again (three times yesterday) pushing out the antifreeze. Any
suggestions what I could check for?

Some history...My other Intrepid temp guage runs around the half way mark
while the problem car is only around 1/4 temp. The heat output is not as
hot as my other car (in the winter) and suspected the heat exchanger to be
partially plugged. The garage had flushed the system and everything
appeared ok., so we suspected the engine may not have been coming up to
temperature and I changed the t'stat again. When the car is in warmer
weather and the conditions force the car to warm up more, the temperature
will increase to the half way point on the guage (like my other Intrpid, and
puts out comparable heat). The (rad) fans do come on when it approaches
the half way point on the temperature guage.

Bleeding the air out of the system with the bleeder valve (by the t'stat)
has not helped. There are no leaks any where. The t'stat has been
replaced (twice). The system has been flushed (several times). I have
swapped out the reservoir (rad) cap with my other car (that does not have
this problem). Why is it intermittently over heating? HELP!
Mark

 

--

What is the code that was set when the check engine lite was on??

Glenn Beasley
Chrysler Tech

 

The check engine light has not come on, on this car, just my other Intrepid
(and it was code 43). This Intrepid has the intermittent over heating
problem. As explained in the other post, the code 43 was due to a misfired
cylinder and a leaky intake manifold.

My chellenge is with this Intrepid (same year and a 3.5L engine too). Any
thoughts?
Mark
Devoted Chysler Customer

 

I am running out of things to try (to fix the overheating problem), so I am
going to try removing the t'stat to test and see if the car still overheats.
I realize it will affect my mileage and engine performance, but it may be
worth it to test for a few days to see if I purchased and installed (a
second) defective t'stat.

Quick summary:
1) Car over heated this winter due to low coolant.
2) I was travelling so I only had the garage replace the t'stat and they
checked for leaks (they thought there was, but could not locate it).
3) Went to my garage and they found a leak in the water pump and replaced
it.
4) Car worked fine initially, but later, intermittently pushed antifreeze
out the overflow.
5) Garage gave me some system flush chemical to try and clean any rust out
of the system.
6) Found a service bulletin on bleeding the air out and did that. Worked ok
for a while with only a couple times pushing antifreeze out the overflow.
7) Last few days repeatedly has started pushing water out the overflow
basically after driving just enough miles for the car to come up to temp
(after the car is shut off).

Other facts: - Temperature registers 1/4 temp on the guage at travelling
speed (vs. 1/2 guage temp on my other Intrepid).
- Fans are coming on when temperature climbs above 1/4 on the temp guage
(when not moving / stopped at an idle) and holds between 1/4 & 1/2 on guage.
- Heat comes out of heater so flow there is apparent.
- Car was pressure tested for leaks (after water pump replaced) with none
found and I have not seen any subsequent leaks.
- Have tried swapping rad cap with my other Intrepid (no difference).
- Now running basically with pure water, since I cannot afford continued
replacement of antifreeze. (glad the freezing weather is past us)

Other thoughts:
- I have Chrysler's 1-800 number and may try calling.
- Could there be a head gasket leak causing air to be pushed into the
cooling system and/or excessive pressure to build up in the cooling system?
If yes, wouldn't the air just push into the overflow reservoir?
- Any other thoughts or suggestions?

Mark

 

Hi Mark...

Not a mechanic, just a retired old electrical guy who loves cars.
Take my guesses as no more than feeble attempts at common sense
guesses, please.

You mentioned flushing the cooling system, but I wonder if there's
any possibility that the rad is really good and plugged up, perhaps
to the point that it should be replaced? Possible a previous
owner or garage filled it up with bars leaks or something similar?

And have you felt the hoses? (the big ones on the rad). Soft and
squishy, perhaps collapsing under some circumstances?

Just thoughts for whatever they may be worth

Take care.

Ken

 

Good thoughts Ken!

In response:
If the rad was partially plugged, I would have expected the temperature
(guage reading) to increase, but it only does that if my coolant level gets
too low (and thus truely forcing the engine to overheat). Anytime there is
sufficient coolant, the temperature guage remains within the noremal 1/4 to
1/2 ranges (normal operating temperature). I thought maybe the temperature
guage may be out of calibration and showing a lower than actual temperature,
but the rad fans will cycle on and off as it approaches the 1/2 way point on
the guage. So unless the rad fans use the same sensor as the temerature
guage, the rad fans cyclying should indicate the engine is operating at
normal temperature. I have a service manual and will check to see if they
could use be using the same sensor.

The rad hose (at least the upper one) can be squished fairly easily and I
had thought of this too, but short of replacing them to eliminate the
potential I am not sure how I can test the hose strength. I have monitored
the hoses at idle, but saw no collapsing. If they are happening at a
higher RPM or while driving it could be a possible cause maybe. Any
suggestions how I can test? It almost appears that under driving
conditions everything is ok, and that the coolant is only expelled after the
car is shut off (which is why I have tried different rad caps). This leads
me to believe that the coolant flow may be restricted somewhere in the block
after the t'stat and temerature sensor (forcing it to travel more through a
bypass) and thus giving a false reading.

I just got back from a trip into town (10 miles each way), and the
temperature rose as expected and remained normal and there was no coolant
being expelled out the overflow in town or at home. I will go out and
recheck now in case the pressure just had not built up enough yet.

Mark

 

Have you got a good radiator cap? Is it the type with a spring-loaded
check valve (the little metal disk in the center of the gasket) instead
of the free-hanging type? Its been my expereince that either a weak cap
or one with the free-hanging check valve (made for a traditional
"coolant recovery tank" system where the overflow bottle isn't
pressurized) will cause coolant loss and eventual overheating in a
first-gen 3.5.

 

It is a pressurized, spring loaded rad cap, and I switched rad caps with my
other Intrepid that is the same year and has the same size 3.5L motor (which
does not have this problem) and the overheating problem remains with the car
(not the rad cap). So I have to assume the rad cap is not the problem.

Mark

 

If the thing is properly bled and the antifreeze ratio is correct and you
have replaced the radiator cap, and it's blowing coolant out the overflow
I would start checking for the presense of water in the engine oil, oil
in the antifreeze, and water coming out of the exhaust. (not condensation)
All signs of a failed head gasket. And it's easy to ruin a head gasket
when you overheat then try limping into a garage.

Ted

 

I had thought about the head gasket and have been montoring the oil, and
have never noticed water or excessive condensation dripping from the tail
pipe, nor have I seen any contamination of the coolant (now just plain
water).

Now I have driven the car a couple times, two seperate days, 10 to 20 miles
each day with both sufficient to bring the car up to temperature and neither
times it has over heated or even spit any water out the reservoir overflow.
The level has remained good. This overheating problem has been intermittent
(where it will work fine for days or weeks, then all of a sudden start
pushing out the coolant). I am still running with the rad cap from my
other Intriped, so again I do not believe it to be that (the other car has
never overheated with it), because I thought it might have been an
intermittent failure of the rad cap. Are there any other things that could
be prone to an intermittent failure (besides the t'stat which I have already
replaced)?

Mark

 

Cooling fan relay?

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

 

I do not think it would be the cooling fan relay, as the fans do come on
anytime the temperature rises (on the guarge) between 1/4 and 1/2 point
(e.g. if stopped for any length of time at a light and just sitting idling
in park). The temperature usually sits at or around the quarter mark on
the guage when moving (vs. the half way mark on my other Intrepid). I had
suspicions about the guage reading, thinking maybe it was just reading low
relative to the actual engine temperature, but it does appear to be fairly
acurate by the fact the fans come on when approaching the halfway point.

The problem is almost as if there is a bit of a coolant restriction within
the block itself and/or when the coolant temperature at the t'stat and
sensors rise to the correct operating temperature, a bypass permits the
coolant to flow more through it than the engine block itself. Could there
possibly be a restrictor missing in a bypass permitting more coolant to pass
through it than the t'stat?

Mark

 

Cooling fan relay?

You said the problem is intermittent. What the fans (or whatever is
causing the problem) do when everything is operating normally (i.e., not
overheating) doesn't mean a thing. I was suggesting an intermittent fan
relay.

Let's try this again: When it does overheat, you have absolutely
verified that the fans are running *at* *that* *time*?

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

 

The fans reliably will come on when the temperature guage reaches between
1/4 and 1/2 on the guage and/or I turn on the air conditioner.

The reason I describe the problem as intermittent, is because the
overheating may occur any time. I have found nothing consistent that I can
relate to a cause for over heating (distance travelled, type of driving such
as highway or in town, ambient outside temperature, etc.).

The problem is starting to occur more frequently now though, as it has
happend twice now this week (and have driven the car at least once per day).
Sometimes the car would work fine for a month and not over heat, but now
with the problem possibly starting to happen more frequently and the weather
getting warmer, maybe the overheating problem is partially related to the
ambient temperature.

I have been considering removing the t'stat from the system for a week or so
(or until I learn what the effect is) to see what happens. I realize this
is not good for engine performance, but unless anyone has other suggestions,
I am not sure what else I can try.

Mark

 

Hi Mark...

Looks like I'm about to join you with cooling problems (leakage),
so I've been thinking a bit about this...

Is it possible that this is really a heads-up that your belt
is at risk? I'm sure I read back a piece that you'd replaced
the water pump, and guess that the belt would have been changed
at the same time? The tensioner?

Anyway, what runs through my mind is that the crank/cams are
driven by the toothed side of the belt, right? A little
sloppiness here might be temporarily forgiven given the teeth.

But the water pump is driven by the smooth side of the
belt, where a little sloppiness could far more easily
let the pump stop turning (or turn more slowly, or perhaps
"stick" intermittently. Perhaps worse, if the water pump
is weeping just a little, it might even tend to "lubricate"
the belt - affecting the smooth side most.

Hopefully the mechanics here will tell us whether or not
this theory holds water (arghh

Take care.

Ken

 

Hi Ken,

I just checked the invoice for when they (my local garage) replaced the
water pump (last December) and yes they had also replaced the belt at the
same time (and also the temperature sensor too). I would expect they
re-adjusted the belt and checked tensioner when this was done, but will ask
them next week.

I called the garage this morning to let them know the problem still exists
and discuss possible next steps, and they said it should not hurt to remove
the t'stat for a period of time to test the functionality (running without
it), and the mechanic indicated they have a solution to put into the coolant
to test for head gasket leaks. Apparently the solution changes colour if
there is and head gasket leakage due to firing or emissions into the
coolant.

This coming Tuesday I am planning to go see them and have the solution
added, and if I get the t'stat out and see how it works prior to then, I
will post an update.

I have the service manual for my car and have read everything in the cooling
system section from beginning to end (other than the missing service
bulletin regarding bleeding the system with a special aid that was issued
later (which I now have a copy of). Everything points to the symptom
description in the bulletin...temperature guage reads low, heater core
temperature not as hot as it should be, but even when I bleed it by
overflowing the reservoir until no more air comes out the bleed valve, the
problem returns. Mabe I do have a head gasket leak that is pushing air
back into the system.?????????? Hopefully I will know next week!

You mention water pump weeping just a little...There is a section in the
service manual regarding a weep hole (black stain on the water pump body),
but apparently it is normal for a little to weep out (according to the
book).. There is a bit more on this in the book, but I am sure your garage
has the same or something similar. Good luck with you problem, and please
keep me posted.

Mark

 

Or it only happens when the fans AREN'T working right? i think that was
Bill's point. The fact that they operate consistently when sitting in
the driveway does NOT mean that they happen to be operating when the
engine is overheating.

 

I believe I understand what you and Bill are saying, but to my knowledge,
turning the air conditioning on over-rides the temperature sensor and forces
the fans on all the time. At least it does sitting in the driveway with the
car at any temeperature (hot or cold), and I thought I had read this
somewhere in the service manual too.

Now if I am incorrect and/or for some reason they are failing during
driving, it will be very difficult to check unless I hook up some sort of
monitoring system. Short of replacing the fans (to see it it does make a
difference), any suggestions as to how else I can test and hopefully
eliminate them as the problem?

Mark

 

Well, the fan is turned on EITHER by high coolant temperature OR by the
AC high-side pressure exceeding a set threshold.

Quick-and-dirty would be to pull over the next time the guage is showing
overheat, pop the hood, and see if they're running.

 

I will check next time it over heats (to see if the fans are running). I
actually just got back from town and it had over heated again. I removed
the t'stat, refilled it and bleed the air out. Ran the car a little bit,
and there was more air to be bled out. Ran it again, same thing. So I am
starting to believe there may be a head gasket leak blowing air into the
coolant. I'll try driving it a bit more but am starting to fear it is due
for more of a major repair. Stay tuned...
Mark