REPAIR QUESTION: Radiator chronically overheats!!

Greetings:

I have an odd problem with my '96 jeep. (Six cylinder engine)

It chronically overheats!

If I drive more than 20 or 30 miles, when I stop, I hear the tell-tale
"gurggling" sound from under the hood. Lift the hood and sure enough,
the water is boiling over into the overflow catch tank.

No warning lights ever come on.

I have tested the antifreeze level. Its to spec.

I took it into the shop and was told I needed a new radiator. Had it
replaced. No change!

Replaced the thermostat. No improvement.

Oddly enough, it doesn't "always" happen. It happens maybe 3-out-of-4
times.

I'd be interested in ANY suggestions on how to address this problem.
What harm is it doing to the engine?

Thank you

Quiet Voice wrote:
>
> Greetings:
>
> I have an odd problem with my '96 jeep. (Six cylinder engine)
>
> It chronically overheats!
>
> If I drive more than 20 or 30 miles, when I stop, I hear the tell-tale
> "gurggling" sound from under the hood. Lift the hood and sure enough,
> the water is boiling over into the overflow catch tank.
>
> No warning lights ever come on.
>
> I have tested the antifreeze level. Its to spec.
>
> I took it into the shop and was told I needed a new radiator. Had it
> replaced. No change!
>
> Replaced the thermostat. No improvement.
>
> Oddly enough, it doesn't "always" happen. It happens maybe 3-out-of-4
> times.
>
> I'd be interested in ANY suggestions on how to address this problem.
> What harm is it doing to the engine?

If you have a temp gauge, does the temp stay in the normal range when the gurgling starts? If so, you may have a blown head
gasket. Exhaust gas is pressurinzing the cooling system, causing the radiator cap to vent and that is the gurgling/boiling over
you see. Test options are to put a pressure gauge on the cooling system to see if its being pressurized or have a chemicl test
of the coolant done to check for exhaust gas contamination. This can all occur without a drop of coolant and oil mixing.

--
Roger

[email protected] (Quiet Voice) wrote in message news:<[email protected]>...
> Greetings:
>
> I have an odd problem with my '96 jeep. (Six cylinder engine)
>
> It chronically overheats!
>
> If I drive more than 20 or 30 miles, when I stop, I hear the tell-tale
> "gurggling" sound from under the hood. Lift the hood and sure enough,
> the water is boiling over into the overflow catch tank.
>
> No warning lights ever come on.
>
> I have tested the antifreeze level. Its to spec.
>
> I took it into the shop and was told I needed a new radiator. Had it
> replaced. No change!
>
> Replaced the thermostat. No improvement.

>
> Oddly enough, it doesn't "always" happen. It happens maybe 3-out-of-4
> times.
>
> I'd be interested in ANY suggestions on how to address this problem.
> What harm is it doing to the engine?
>
> Thank you

Wrangler, cherokee? My cherokee was overheating just the same as you
explain. It turns out that when they run low on water, or have a
radiator changed, the cooling system has to be primed. on my 91 the
water overflow and fill tank sits lower than the radiator hoses. The
hose had to be taken off and filled with coolant to get proper flow
through the system. hope this helps.

Hi and thanks for the response.

You asked:
> If you have a temp gauge, does the temp stay in the normal range when the >gurgling starts?

What I menat when I said that there are no warning lights is that I
get *NO* indications of overtemp. I have to numerical themometer. But
the overtemp warning light does not go off.

I had the radiator replaced recently. I'd think they'd have been able
to tell if the head gasket was blown....wouldn't they?

Also, if it were a head gasket problem wouldn't it always occur? My
problem occurs only for 3 out of 4 trips over about 20~30 miles.

Are there any other possible causes?

Roger Brown <[email protected]> wrote in message news:<[email protected]>...
> Quiet Voice wrote:
> >
> > Greetings:
> >
> > I have an odd problem with my '96 jeep. (Six cylinder engine)
> >
> > It chronically overheats!
> >
> > If I drive more than 20 or 30 miles, when I stop, I hear the tell-tale
> > "gurggling" sound from under the hood. Lift the hood and sure enough,
> > the water is boiling over into the overflow catch tank.
> >
> > No warning lights ever come on.
> >
> > I have tested the antifreeze level. Its to spec.
> >
> > I took it into the shop and was told I needed a new radiator. Had it
> > replaced. No change!
> >
> > Replaced the thermostat. No improvement.
> >
> > Oddly enough, it doesn't "always" happen. It happens maybe 3-out-of-4
> > times.
> >
> > I'd be interested in ANY suggestions on how to address this problem.
> > What harm is it doing to the engine?
>
> If you have a temp gauge, does the temp stay in the normal range when the gurgling starts? If so, you may have a blown head
> gasket. Exhaust gas is pressurinzing the cooling system, causing the radiator cap to vent and that is the gurgling/boiling over
> you see. Test options are to put a pressure gauge on the cooling system to see if its being pressurized or have a chemicl test
> of the coolant done to check for exhaust gas contamination. This can all occur without a drop of coolant and oil mixing.

Quiet Voice wrote:
>
> Hi and thanks for the response.
>
> You asked:
> > If you have a temp gauge, does the temp stay in the normal range when the >gurgling starts?
>
> What I menat when I said that there are no warning lights is that I
> get *NO* indications of overtemp. I have to numerical themometer. But
> the overtemp warning light does not go off.

Exactly what happened in my case. I would see fairly normal engine temps, then see the steam from the radiator "boiling over"
then the engine would start to overheat as it was low on coolant. It was not boiling over from heat, rather the exhaust was
pressurizing the radiator enough to cause the rad. cap to open, releasing the pressure and then just like opening the cap on a
bottle of soda, the pressurized coolant would surge out the open cap until it closed.

> I had the radiator replaced recently. I'd think they'd have been able
> to tell if the head gasket was blown....wouldn't they?

Only if the tested for it. I assume they but in a "good" radiator. In my Toyota, my overheating problems started when the PO
had a minor fender bender that damaged the facotry radiator. It was repaired along with some body work and the unit put in was
inadequate. It cooled fine unless you pushed it in the heat (80+) then it would overheat. This lead to the head warping then
cracking, blowing out the coolant in the radiator. When I eventually tracked down the cause of the problem, replaced the
inadequate 2-row radiator with a heavy duty 3-row and the problems were solved.

> Also, if it were a head gasket problem wouldn't it always occur? My
> problem occurs only for 3 out of 4 trips over about 20~30 miles.

Well it takes the right engine conditions to cause it to happen. I had this happen in my Toyota, usually would go when on a
steep grade, worse when the outside air temps were higher.

> Are there any other possible causes?

Possibly engine running lean or the radiator cap is defective or you have a leak somewhere in the system. Get the cooling
system pressure tested or have the chemical test doen on the coolant, it'll give you clue.

--
Roger

Quiet Voice wrote:

> Greetings:
>
> I have an odd problem with my '96 jeep. (Six cylinder engine)
>
> It chronically overheats!

If that's the case, then you need to check the water pump. Does it
circulate coolant or not?

I had a problem similiar to yours and someone told me he thought it could
be a blown head gasket.

Pull off a hose or two and see if water comes shooting out with the engine
cranked and running? if not, is the water pump any good? in my case, the
pump's propeller had disintegrated so much that there was no propeller
left, and of course, there was no water pressure it put into the system,
but I could still drive the car.

Someone had put the thermostat in the wrong way too but anyway. Check the
water pump if it's not too much trouble. pull off a heater hose.

>
> If I drive more than 20 or 30 miles, when I stop, I hear the tell-tale
> "gurggling" sound from under the hood. Lift the hood and sure enough,
> the water is boiling over into the overflow catch tank.
>
> No warning lights ever come on.
>
> I have tested the antifreeze level. Its to spec.
>
> I took it into the shop and was told I needed a new radiator. Had it
> replaced. No change!
>
> Replaced the thermostat. No improvement.
>
> Oddly enough, it doesn't "always" happen. It happens maybe 3-out-of-4
> times.
>
> I'd be interested in ANY suggestions on how to address this problem.
> What harm is it doing to the engine?
>
> Thank you

Two or three things come to mind.

First, they can be a bugger to get the air out of. Check the rad and
heater hoses to make sure they don't run above the level of the coolant
or park it on a steep up hill and bleed the air out that way.

Second, the fan has a clutch on it. To make sure it is working, get the
engine fully hot and have someone shut it down while you watch the fan.
A good fan clutch will stop the fan almost instantly when hot. If the
fan keeps on spinning, the clutch needs replacing.

Third, the rad is 'supposed' to burp out into the overflow when hot,
then it sucks back in when cooling off. This is normal and how it is
supposed to work.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Quiet Voice wrote:
>
> Greetings:
>
> I have an odd problem with my '96 jeep. (Six cylinder engine)
>
> It chronically overheats!
>
> If I drive more than 20 or 30 miles, when I stop, I hear the tell-tale
> "gurggling" sound from under the hood. Lift the hood and sure enough,
> the water is boiling over into the overflow catch tank.
>
> No warning lights ever come on.
>
> I have tested the antifreeze level. Its to spec.
>
> I took it into the shop and was told I needed a new radiator. Had it
> replaced. No change!
>
> Replaced the thermostat. No improvement.
>
> Oddly enough, it doesn't "always" happen. It happens maybe 3-out-of-4
> times.
>
> I'd be interested in ANY suggestions on how to address this problem.
> What harm is it doing to the engine?
>
> Thank you