Hello,
I am working on a 1999 Dodge Grand Caravan and am having a mysterious problem with it running hot.
Other forums have offered the routine common answers but were not able to help me actually tackle this problem which seems to be a bit more difficult to track down.
Anyone who has (or had) a 2006 or earlier Dodge Caravan with a 3.3L and is familiar with this vehicle and this issue it would be nice to talk to you.
Thanks
Welcome to the forum…
Good idea to tell us what this mysterious problem with it running hot is so maybe someone on here can help…
I have a 1999 Grand Caravan with a 3.3L sitting in my yard right now, bought it back in 2000… But that still doesn’t mean I have ever had the same mysterious problem as you, or can even help you… But that doesn’t mean that someone else hasn’t worked on one in the past and can tell you the answer 1st try…
Much better to inform us of your issue(s) and what you have already done then to judge us before given us a chance to even try…
Yes you may get some bad answers but you will get some good answers also, will they be the correct ones, only time will tell…
And as far as you asking for Anyone who has (or had) a 2006 or earlier Dodge Caravan with a 3.3L and is familiar with this vehicle and this issue you never told us the issue…
Hello,
Thank you. I suppose I am just a bit frustrated that this problem seems so elusive.
I went through this issue at length at another car forum but the moderator decided to close my thread after giving what he considered sufficient information. But the problem was not resolved…
The vehicle sat unused for 4 years until I recently decided to bring it back to service.
The issue is basically that the vehicle is overheating.
The “mystery” is that I have tried everything commonly associated with overheating that has been suggested or that I can think of.
The vehicle has a new temperature sensor, a new radiator cap, a new water pump, a new Fan Control Relay and the fans themselves are working. The radiator coolant level has been checked and rechecked. I have carefully checked every wire related to the cooling system from the PCM to each device and found no wiring or grounding issues.
Yesterday I observed that even when the cooling fans come on, the temperature continues to rise. It slows down the rate of rise, but it continues to rise. When the fans come on I would expect a big drop in temp. I am using an ELM327 OBD2 device to monitor the temps. I verified the LM327 reading with a laser thermometer at the base of the temp sensor and at the radiator.
I removed the fans and carefully verified that there are no radiator/condenser obstructions. I bench tested the fans and they work properly on the bench. The vehicle is not losing coolant. The hoses are very firm once the engine is fully warm. There is no steam or odd odor from the exhaust tailpipe. I had suspected a catalyst blockage.
Using a thermal camera, I could see that at 180F (approx) the hot coolant begins to flow through the radiator. Only the top half of the radiator seems to show hot coolant, which if I’m not mistaken indicates I have a double pass radiator and also the inlet and outlet are on the same end of the radiator. What seems a little odd here is that the bottom half of the radiator shows very little heated coolant. It could just be my misinterpretation.
The fans turn on at 225F (instead of 214F as they should), so there is a problem. Maybe with the PCM. Not sure.
It is a odd problem or so I feel and nothing seems to add up. What seems apparent at one point seems random or different later.
Personally, I am leaning towards believing it could be a head gasket issue, a radiator flow issue due to sitting for 4 years, or an exhaust restriction. At the other forum I was told an exhaust restriction could not cause engine overheating.
Thank you for any further suggestions or input. Please accept my apology for the initial problem presentation.
Hose inlet temp? Hose outlet temp? Remove/replace radiator? Flush it?
That seems like the radiator has built up scale. My thought, if this is the original, 24 year old, radiator, is to replace it.
Your van is 24-years old and you’re presumably still on the original radiator and thermostat . . . ?1
I would replace both, along with all of the hoses
Think of it as preventive maintenance, and if it takes care of the overheating, great
Yep, radiator was my first thought, do the thermostat too. Common for cars of that age to need a radiator. I’d buy it from a local parts store to make sure I got the right one (bring it with you to the store).
Seems like the thermostat is opening but the radiator seems clogged.
Replace the radiator and a new t-stat at the same time could not hurt.
Hi,
I installed a new radiator 6 years ago. But still, this one sat unused for 4 years so it could have deteriorated internally.
I forgot to mention that I just changed the thermostat a few days ago also.
Thanks all for the replies. Really appreciated. You too Tom. 
I think the consensus is good. Radiator could be the issue.
Have you used a coolant block tester to check for a blown head gasket?
The kits are pretty cheap and any decent auto parts store should have them in stock. Or order it on amazon
I have had a couple of those minivans. allpar.com is a Chrysler-specific website. They have a minivan forum, which has helped me a few times over the years. You might get some good ideas there. Good luck.
BTW I just replaced the OEM radiator on my 2007 Town and Country with 200K+ miles. It was leaking a bit after a long road trip. Good to go now.
Right? Thanks.
If the radiator doesn’t do it…that’s next.
I did this test on this vehicle back on 08-08-2014, around 25,000 miles ago. All passed then.
But it sat for 4 years.
No visible coolant leaks. No coolant loss. No oil in the water. No water in the oil. No exhaust steam visible. No coolant smell that I’ve noticed at the tail pipe. Weird.
I would have thought a HG leak serious enough to cause this overheating would have resulted in at least some steam at the tail pipe or coolant loss. Who knows.
I guess I could do a compression test on each cylinder too?
Cool.
I also have a 2006 with a 3.3L
I like the power upgrade in the 2005-2007
I wish I could put the 2006-2007 motor in the 1999
The PCM turns on the radiator fans @ 220 F, your observations are normal. How hot is the coolant when the engine is overheating?
Is the radiator fan relay properly mounted to the frame rail?
I presume there’s not a whole lot of tiny bubbles appearing in the coolant, worse when rev’ing the engine. If so, good chance replacing the radiator will help. However, you could first try just replacing the cooling system pressure cap. If the cooling system pressure isn’t properly regulated, it won’t cool the engine properly. From what you say, it seems like the engine compartment fans are working properly.
Good news is your new radiator should be free, should have a limited lifetime warranty on it…
I would flush the engine block and heater core while the rad is out…
Also make sure the cooling fans are blowing the correct way… the air should be moving from the grill towards the engine, if unsure you can use a paper towel or shop rag and hold it in front of the fans… never know…
What if I told you that a transmission that is running hot can cause the engine to overheat?
Tester
I’d never buy a 99 dodge anything.
People have their personal preferences.
I absolutely love this vehicle and it has been incredibly reliable and low maintenance over the 15 years or so that I’ve owned it. Of course, I do all the maintenance myself.
Over those 15 years I have spent $5,800 TOTAL on this vehicle and that includes tires and ALL parts and maintenance. If you do the math that is outstanding value. $386 per year.
Mercedes Benz actually owned Chrysler/Dodge in 1999 and maybe it’s just coincidence that some of their best vehicles came out during that time span?
The last Chrysler minivans were made by Fiat and I don’t want any of those.
When I see the temps rise above 240F I turn it off.
Yes, the fan relay is mounted firmly to the frame, no rust.