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Intrepid Overheating

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coolant
5K views 12 replies 6 participants last post by  mr70mopar 
#1 ·
My 02 Intrepid 3.5L was running great. I changed the oil.

Now it is overheating. I can control the temp through the use of the defrost. The air entering the cabin is HOT, so I think that means the t-stat is working OK.

I have two forced cooling fans on the radiator, I think one of them has quit working, could that cause this overheating?

On the way to work this morn, when the temp climbed over the halway mark of the range indicator, I pulled over and let it idle, temp came back down.

I am puzzled. Any ideas?
 
#2 ·
The fact that you have heat to the interior of the car shows that your t-stat isn't stuck closed and the coolant is making its way through the heater core. Check your coolant reservoir and make sure it's at the correct level. You could also open the bleeder that's located on the t-stat housing to insure you don't have any air bubbles in the system. I wouldn't expect this to be the problem though, as it's generally only an issue when you've opened the system, for a t-stat or radiator change for example. The oil change shouldn't have made any difference...unless you forgot to put oil back in the motor.
 
#3 ·
So here's where we are

1. Start car, no fans.
2. Not up to temp yet - About 1 minute later BOTH fans run on low speed.
3. Not up to temp yet - AC On, both fans run on low speed.
4. Up to temp - Fan 1 switches to high speed, fan 2 turns off
5. Up to temp - AC On, Fan 1 still on high, Fan 2 off.
6. Up to temp - few minutes later, needle now at almost high point on scale, turn on defrost, get needle to middle of range, turn off car.

The service manual says that if the upper hose is hot on a 3.5 L the t-stat is working. My upper hose is plenty hot.

There are no codes offered by the keying method. There are 5 error codes available for radiator fan problems. No codes flash.

It would appear the Fan 2 relay on high is bad or it is not being turned on.

Tonight I am going to switch relays from 1 to 2 and see if the other fan works, then I know it is a relay.

Any other ideas?
 
#4 ·
...4. Up to temp - Fan 1 switches to high speed, fan 2 turns off
5. Up to temp - AC On, Fan 1 still on high, Fan 2 off...
That's proof that the problem is in the fans or the fan controls. Both fans are supposed to run in tandem - whatever speed they are running at at any given moment - off, lo, or hi - they both should be running the same speed.

Could be one of the relays in the PDC. Try swapping the two fan relays and see if the problem changes - that's not to fix anything - just an experiment to see if one of the relays is a problem. Don't overheat your engine to do the experiment, but you should be able to see the fan operation pretty quickly.

(This is the 3rd fan question I've answered in a row - strange.)
 
#6 ·
Yep - I should have suggested that too - I wasn't looking at the schematics when I posted. With a little luck, maybe a relay just needs to be re-seated in the socket.
 
#7 ·
Make sure both upper and lower hose are hot. If the upper hose is hot and the lower hose is cold your thermostat is not opening. If the thermostat is not opening it can be one if not both of two reasons. Defective thermostat or debris in the thermostat gallery. These engine are bad for collecting debris between the head gasket and the head in the gallery that feeds the thermostat. Once that gallery is plugged the thermostat will no longer open. Unfortenatly the only way to rememdy that problem is to pull the left head off and clean the debris out of the passage. Just finished doing one today for the same reason.
 
#8 ·
Thanks guys for the updates. Here's what the dealer said yesterday. Anything I should be doing while I haev the car this far apart, short of taking the heads off?

I posted a while back about my Intrepid suddenly overheating. I parked it Fri night, changed the oil and wife drove it sat morn and it starts overheating. Never steamed or boiled, but the temp gauge went all the way to just below red.

So, I farted around with it for a day or two, decided all I knew was not fixing it. It would overheat idling, it would overheat at highway speeds. I have no idea what the problem was. The service manual says if the upper hose is hot, the t-stat is working properly. That is the entire entry in the FSM. Upper hose was hot.

So, I take to dealer. After usual BS of not working on it at scheduled time, as a matter of fact they did not work on it until I called them. After my third call the service manager, he says that the guy working on it thinks it is either the t-stat or the radiator. Then, while we are talking he states "It is clearly the radiator, you need a new one." I'm thinking the car has been running dead nuts in the middle of the temp range forever, no temp creep, no idication of the radiator reducing flow. He says "I will call you back with price."

He calls back. "$750 for radiator, you should change T-stat too, and a fill and flush. That'll be $1100." :shock:

I told him, have it ready to be picked up I cannot afford that. He said "you don't want to fix it?" I said it will get fixed, just not for that much. He said, there is a $100 diagnostic fee. I said no problem, thanks for the help in finding out what is wrong.

So, I call my parts store friend and we talk about the car. We decided that the Tstat will be replaced and the radiator flow checked. Even if I need a radiator, I will have spent 5 hours, and $350 dollars to fix this.

I don't know how people who do not work on cars afford to have them repaired. An $1100 radiator?

Oh and BTW, the clamps on the Intrepid cooling system SUCK. I am replacing them all with properly oriented screw clamps. One cool thing though, is if I go ahead and do the preventative maintenance on the timing belt and change it, it looks fairly easy after you remove the front radiator support/cover. LOTS of room. Unlike in my ram when I did to that.
 
#9 ·
Dealers

"He calls back. "$750 for radiator, you should change T-stat too, and a fill and flush. That'll be $1100." :shock:
I told him, have it ready to be picked up I cannot afford that. He said "you don't want to fix it?" I said it will get fixed, just not for that much. He said, there is a $100 diagnostic fee. I said no problem, thanks for the help in finding out what is wrong.
So, I call my parts store friend and we talk about the car. We decided that the Tstat will be replaced and the radiator flow checked. Even if I need a radiator, I will have spent 5 hours, and $350 dollars to fix this.
I don't know how people who do not work on cars afford to have them repaired. An $1100 radiator?"
Now you know how dealers can discount cars: they make their money in the service shop. The dealer wanted $550 to replace the cooling fans in mine, and I bought them for $99 and did it myself in 45 minutes. Unless it is warranty service, the dealer is the last place to have anything done.
 
#10 ·
Well, glad you found it... I'd have said T-stat first... I highly doubt radiator, but like it was mentioned, it could be debris... back flush the radiator with a garden hose, you could also do a back yard flow check that way too... Clean the fins in the radiator and condensor while you're at it... you never know, you might find you have a shopping sack crammed in there or something...
 
#13 ·
Welll, crap.

Radiator guy called. Flow and pressure check, no problems at all. I expected this because the car has not been acting like the radiator is dying. So, great. I saved the $160 on a radiator, only cost is time.

We kept talking and he told me how they fail, he's replcaed two this week, etc. Said he wanted to open the tank and look. BUT it may cost me a new radiator because the tabs do not always reseal. I made the decision to replace it. 100K miles, and something is wrong, so let's look.

I show up over lunch to get new radiator and he says look at what is in your radiator. Three tubes partially blocked by FRESH ALUMINUM SHAVINGS!

Water Pump? I think so. What else is in the water path that could be shaving aluminum while within the flow. Nothing else turns.

Of course, on an Intrepid 3.5L, the water pump is turned by timing belt, so I have to replace all that crap now.
 
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