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1996 Dodge Intrepid 3.5 Overheating - PLEASE HELP

12K views 7 replies 7 participants last post by  Enginebuilder 
#1 ·
I have a Dodge Intrepid 3.5 1996 with 169,000 miles. It is
overheating. It drips out the overflow tube when it gets hot. Normally
drips small amounts that after a few days cause the car to overheat.
If it really gets hot it pours out the overflow tube. When the air is
cooler, the car does not overheat. Takes about 30-45 minutes coming
home from work to overheat.

A mechanic friend (and several garages) have worked on it and did the
following to no avail:
1. Replaced head gasket (thought it might be blown)
2. Replaced thermostat
3. Replaced temperature sensor (twice)
4. New water pump about a year ago.
5. Timing belt
6. Computer (PCM)
7. Radiator cap from dealer
8. RFID control for fans
9. radiator rodded out (was badly stopped up)

He has switched fuses in the fuse box for the radiator fans. Also
grounded the fuses to see that the high and low radiator fans do come
on.
He has used a scan tool and the low radiator fans comes on at 230
(which according to the specs is correct).

Browsing the usenet groups, I have seen this problem occur with the
Intrepid, but as yet I have not found anyone that has actually found
the problem.

Any help, hints, checks would be greatly appreciated.

Thanks
 
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#3 ·
This sounds nearly like the problem I am having with my 97 with the 3.5. The car was given to me about a year ago in December. My grandmother said that it hasn't put out good heat for a while. I took it in to a local trustworthy shop and they checked things out and found that the thermostat that my grandmother had just had replaced at a dealership was actually in crooked. I went ahead and had them put in a new one. They bled the cooling system and gave it the go for the trip I was making. The heat blew good for a while then started to cool down. Driving it to New York for the holidays (normally an 8-10 hour drive), the radiator blew out. I replaced the radiator and bled the system and it blew luke warm all the way home. We managed through the winter as it was. We believe it to be the heater core clogged.

We didn't worry about it until mid August, driving with the A/C on, we overheated and found that it had blown all of the coolant out of the overflow tube. At that point, I was able to reproduce the problem by turning on any of the temperature controls and it would start dumping out of the overflow tube.

This morning it did it to my wife without having any of the temp controls turned on during a short 5 mile round trip....I've since driven it about 40 miles without reproducing it. I'm still thinking the heater core is the culprit and with winter coming, I need to change it. The fun I'm having is that no shops around me will do a heater core in these cars because it's "too big of a job", so I'm on my own.
 
#5 ·
Well? I'm interested in your results.

I also own the same car, model, year, with almost the same mileage. I ended up putting in a re-manufactured engine (all new parts). It was told to me I had a micro crack in the header over the rear cylinders.

BUT check this out....New engines, New Radiator, and just a few months ago, New Fans. Today....it over heated again (Less than 25K on the new everything). I believe the cooling system is under engineered. Forget the thermostat. I'm going yank it out until I need heat.
 
#6 ·
The 3.5 has a problem with any air getting into it's system. As soon as it gets a little low on coolant, boiling of the coolant begins. Steam opens the overflow, causing it to blow the coolant out until it overheats.
What needs done is a pressure test. To find any possible leak. If it can hold the same pressure for an hour, your good. Plus when it's filled the bleeder screw near the thermostat must be opened. I even will open it after it's fully warmed up. Watching not to get burned of course. When nothing but a stream of coolant comes out, I then top it off. When bleeding try to keep the reservoir full as possible.

I'll first fill it up with antifreeze at a 50/50 mix, with the bleeder open. Close the bleeder and top off the reservoir, once coolant begins flowing out the bleeder. Doing so on an incline, with the rearend at the lower side of the incline. This forces any air up towards the thermostat.
I'll then fire it up and turn the heater on full heat. This insures you are getting any air out the heater core. Once the top hose begins feeling warm the thermostat is now open. I then open the bleeder again. Once nothing but liquid comes out, i'll close it at this point, then top off the reservoir.
Then take it down the road for a trip. Bring it back and open the bleeder again, just to make sure no air is present. If none was found I'll let it cool down and top it off again.
If air was found I will go for another drive. Open it again. If it is still getting air, you most likely need a power flush.
Do a pressure test of the radiator cap. To make sure it isn't the problem, I forgot to mention.
 
#8 ·
This.

I owned a 1997 Dodge Intrepid Sport with a 3.5 v-6. When purchased (for $300) the car would overheat at a moments notice, and had a bad head gasket.

Even after repairing the HG, the car would still overheat; randomly, and without warning.

Followed the above procedure, outlined by StandOnCliff, and no more overheating. Taking the car for a ride, with the heater on, is critical to getting the last bit of air out of the system. If there is any air at all, the coolant will boil over, and radiator will spill its contents all over the road.
 
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