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1999 Dodge Caravan Running Hot
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WrenchPincher
User
Jun 15, 2023, 5:39 AM
Post #1 of 49
(2941 views)
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1999 Dodge Caravan Running Hot
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1999 Dodge Grand Caravan 3.3L Flex 200,000+ miles
Hello,I am having an overheating issue with my 1999 Dodge Grand Caravan.
The vehicle sat unused for 4 years and I have just recently started using it again.
If I am not moving and continue to run the engine temps will climb over 250F
I do not recall any overheating issues 4 years ago before I stopped driving it.
As long as I am moving the temps will remain between 205 and 224F
To narrow the replies, let me state what I have tested, done or observed. - New Radiator cap.
- New thermostat
- New Fan Relay
- Replaced Radiator about 30,000 miles ago in 2014
- The system builds and holds good pressure, very firm hoses.
- No leaks.
- Removed and tested EGR valve assembly and solenoid valve. (good)
- No oil contamination in the coolant, no water loss, no exhaust steam, no smell of coolant. (headgasket)
- Radiator is full of coolant to the top.
- Temperature sensor readings verified by using a laser thermometer at the casting around the sensor installation point (matched sensor readings exactly)
- Took Laser temp readings at the exhaust manifold before the cat and after the cat immediately after a 4 mile ride. 550F before the cat. 625F after the cat.
- The radiator fans are coming on as per the OEM service manual
- No smell of rotten eggs (sulfur)
- Reasonably good power (for this vehicle at this age), seems to pull good during acceleration up to 60. Didn't try to go over 60mph but felt as though it would easily.
- Water pump is 12 years old.
- No OBD2 codes whatsoever. All clear.
I am suspecting some kind of water pump vane or shaft failure but not sure. (New one on hand)
Could definitely be a head gasket issue at this age and after sitting for 4 years. I will need to run additional tests to determine. Any thoughts would be appreciated.
Thanks
(This post was edited by WrenchPincher on Jun 15, 2023, 5:59 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 15, 2023, 8:04 AM
Post #3 of 49
(2910 views)
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Re: 1999 Dodge Caravan Running Hot
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If this will do this in front you, mist water thru grill see how fast it cools to t-stat's temp. If instantly kinda shows coolant moving is ok leaves air enough to stay as intended.
Time matters in assorted ways by miles water pumps OK if lousy coolant allowed to harm that a maybe of many,
Tom
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WrenchPincher
User
Jun 15, 2023, 9:06 AM
Post #4 of 49
(2902 views)
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Re: 1999 Dodge Caravan Running Hot
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The radiator fans are coming on as per the OEM service manual What exactly does that mean? It means that I followed the OEM Service Manual to test the fans and all tests were passed. This is a 2 speed fan system that is intentionally designed to run hotter when stopped. The questions to be answered are..... Is the fan reaching both speeds? YES Does the temp continue to climb when the fan comes on? YES The fact that driving the vehicle brings the temp down points directly to the fan operation. I do not consider 224F+ "normal" with this vehicle while driving. Even on the hottest summer day with the AC going it used to remain below 210F. Also make sure the system is full of coolant, not just the reserve reservoir if it has a separate radiator cap. I will check it again. |
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WrenchPincher
User
Jun 15, 2023, 9:13 AM
Post #5 of 49
(2899 views)
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Re: 1999 Dodge Caravan Running Hot
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OK, good idea with the mist through the radiator.Will try that.
As far as the water pump, I'm wondering if the vanes are slipping on the shaft?The over heating problem seems to be getting a little worse each time I drive it.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 15, 2023, 9:45 AM
Post #6 of 49
(2895 views)
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Re: 1999 Dodge Caravan Running Hot
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224F can be normal is why systems are under pressure raises boiling points.
So if a 16# pressure cap (plain water @ sea level) would boil at 260F a tad more if 50/50 antifreeze. That's mandatory or hot vapor is NG for cooling.
Vehicles for ages now run over boiling points can't allow that.
Feel pressure at large diameter hose, stone cold/cool (not run for quite a while) then start it and go feel hose @ zero pressure and wait it will buildup. If fast to build up usually exhaust gasses are entering cooling system also high chance but exceptions it wouldn't draw back coolant from remote tank might look too full after a few cycles?
Heat, volume of a gallon changes is why the pressure 3F up for each lb of pressure it holds.
Think pressure cookers if they still sell those :0
Tom
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WrenchPincher
User
Jun 15, 2023, 10:33 AM
Post #7 of 49
(2886 views)
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Re: 1999 Dodge Caravan Running Hot
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Thanks Tom.
Will do.
BTW...Water pump removed...looked almost as good as the day I installed it....12 years ago. No leaks. Vanes solid on shaft, no wobble, Excellent Water pump!
It is a Gates water pump. I bought the exact same one for replacement. Hopefully they haven't dropped their quality standards since then.
(This post was edited by WrenchPincher on Jun 15, 2023, 10:39 AM)
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WrenchPincher
User
Jun 15, 2023, 10:41 AM
Post #9 of 49
(2878 views)
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Re: 1999 Dodge Caravan Running Hot
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Ok, thanks Hammer,
The pump looks great. Probably not the issue.
I'll go over the "burping" process a few times to make sure all the air is out.
Other than that, I'm out of ideas.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 15, 2023, 10:44 AM
Post #10 of 49
(2875 views)
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Re: 1999 Dodge Caravan Running Hot
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I keep coming back to the fan having issues.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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WrenchPincher
User
Jun 15, 2023, 11:29 AM
Post #11 of 49
(2864 views)
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Re: 1999 Dodge Caravan Running Hot
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I would like to agree but the fans run at high speed and never turn off because the engine doesn't cool down.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 15, 2023, 11:31 AM
Post #12 of 49
(2861 views)
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Re: 1999 Dodge Caravan Running Hot
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What happens if you just bring the engine RPMs up while sitting still.
Is there anything restricting the front of the radiator?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 15, 2023, 11:32 AM
Post #13 of 49
(2859 views)
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Re: 1999 Dodge Caravan Running Hot
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RE: Water pumps> They must both hold pressure & vacuum (cooling down) so use like a double lip seal or spring inside seals. Sitting you don't see gun rust plain humidity rough up precision parts like where things like that seal.
Time does crazy things find with use oil leaks and things, brake items. Much, much better if run now and then or flipping day to put one to bed that long. It kills new cars in a year if outside - of course - can't store them all in a museum chamber.
It's ok just expect stuff that isn't by some book. Notice the parts you buy are greasy or super sealed so don't fail before sold? Tom
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 15, 2023, 12:34 PM
Post #15 of 49
(2848 views)
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Re: 1999 Dodge Caravan Running Hot
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Low speed should be coming on at 215 and high speed at 225 or when the AC is on.
Let me know if you need any wiring diagrams or anything.
Also these vans had a ton of trouble with the electronic relays both with the relay itself and the plug going into it.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jun 15, 2023, 12:37 PM)
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WrenchPincher
User
Jun 16, 2023, 6:14 AM
Post #16 of 49
(2786 views)
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Re: 1999 Dodge Caravan Running Hot
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I carefully checked all wiring between the PCM, Fan Control Relay and the Fans and found no problems.Each wire had continuity at both intended ends and the B+ wire from the PDC has full battery voltage at the relay as well.All ground wires tested good. The fans respond normally to 12v applied directly..
That leaves a few possibilities....
1). The Relay is bad (Even though it is brand new)
2). The Temperature Sensor is bad (even though the correct temperature is being reported and can be read via OBD2 port)
3). The PCM is faulty and not sending the correct output to the fan relay.
To Test the relay I could apply 12v to the Fan Control Relay 12v input terminal that is normally fed by the PCM. On this vehicle that is a 14G LG/DB wire from the PCN to the FCR.If the fans come on then it would indicate the PCM is faulty since the PCM is in fact receiving the correct temperature reading (voltage signal) from the Temperature Sensor.
If the fans do not come on, it would indicate a bad Fan Control Relay.
Have I missed anything?
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 16, 2023, 6:26 AM
Post #17 of 49
(2784 views)
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Re: 1999 Dodge Caravan Running Hot
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I believe your logic in testing the relay is faulty and could result in frying the PCM.
The best way to diagnose this is with a scan tool.
You can monitor the temps and the status of the fan control. If you see the fan control switch to "on" and the fan doesn't come on, then the issue is with the relay. I have to stress that there are known problems with the connector to the relay overheating and loosening the contacts to the relay.
This relay is controlled by Pulse Width Modulation so I wouldn't be trying to jump anything at the relay.
If you are seeing the correct temp reading in the computer, then the sensor is fine.
You can bypass all that temp testing by just turning the AC on as that will trigger the fan to on.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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WrenchPincher
User
Jun 16, 2023, 3:57 PM
Post #18 of 49
(2756 views)
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Re: 1999 Dodge Caravan Running Hot
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I agree. And I have two scan tools. An xTool D7 and an XTool D8.Neither will allow me to actuate the Fans on this year Dodge Caravan.These tools do not seem to be capable of Bi-Directional communications with the 1999 Dodge Grand Caravan and that is the issue I have presented to xTool.
I currently have an open ticket with XTool and they say their technicians are "investigating", but they have been saying that for two weeks now and won't give me any solid info.Just that they will get back to me soon.
I appreciate your concern.
You can safely measure DC or PWM DC output with most modern multimeters because they will display the average voltage and the FSM specification for the output gives that value as the reference.If you know otherwise please advise.
Regarding the Temperature readings.Yes, that my assumption. If the OBD2 and scan tool were displaying the correct temps as verified by a laser thermometer, then the sensor is probably working.To back that up, I followed the FSM test procedures for the ETC sensor.First I tested the ground wire and got a good ground on that wire.Next I tested the PCM output (5V according to the FSM) and it was nearly dead on at 5.047vI tested the ground wire at the ETC connector all the way through the harness back to the PCM and found no defects.The ECT sensor measured 7K ohm with engine at ambient temp, and 800 ohms at 200F. The FSM for 70F reading is 7K - 13K ohms. At 200F - 700-1000 ohms Needless to say, nothing so far has revealed any issues, yet the fans are not coming on at the prescribed temp.I welcome any further suggestions and still believe you are correct that the fans are not operating correctly.
Thanks again for your help.
Your vast knowledge and experience are rare.
(This post was edited by WrenchPincher on Jun 16, 2023, 4:01 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 16, 2023, 4:07 PM
Post #19 of 49
(2752 views)
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Re: 1999 Dodge Caravan Running Hot
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It doesn't need to be bidirectional. You should be able to just observe data and it should tell you when the fan is prompted to come on.
I would definitely take a hard look at the connector to the solid state relay. I can't emphasize how many times I have found that to be a problem.
Once the scanner confirms the fan has been prompted you should tug on the wiring around the relay looking for a response.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 16, 2023, 11:58 PM
Post #23 of 49
(2717 views)
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Re: 1999 Dodge Caravan Running Hot
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? Is there a clear path for air to flow thru? 4 YEARS! Time enough for generations of rodents to clog the dang air gap between condenser and radiator. Voila - nothing is going to be spot on.
TMK it's tough to see there must know crude situation of what that time allowed to go wrong and prove it so much as has a path for air? Tom
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