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Discussion Starter #1
Hello everyone,

I purchased a 2001 Caravan a few weeks ago and it has been running cold ever since. It takes very long to warm up and when on the highway it barely gets above the C mark. In heavy traffic or when idling for a while it gets up to the next mark.
This is in a Vancouver where the lowest temperature we've seen so far is +2 Celsius.
I web search for similar issue and the suggestion is to replace the thermostat so I took it to my crappy mechanic (he's cheap, no wonder) and he insisted that there was nothing wrong with the thermostat as he replaced it and the pump while back for the old owner ( I bought the van through him) and all he did was bleed the system by running the van with the radiator cap off for a while then told me everything was OK. Well, it still runs cold.

No coolant leak anywhere.
I topped off the coolant is good in the radiator and the reservoir.

Should I just replace the thermostat or could there be something else?

Thanks
 

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Discussion Starter #4
I should've mentioned that when I turn on the heat inside it follows the same pattern, it only gets warm when the gauge goes up a bit. Does that eliminate the sensor or still [possible?
 

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fix it if you can
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If you have little to no heat, it's the thermostat - take a peak in the radiator when you start it cold, if you see coolant flowing the t-stat is open (when it should be closed)...
If you can't replace it right away, you can cut a piece of cardboard to cover no more than 50% of radiator and place it behind the fascia.
 

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Discussion Starter #6
Thanks, I will do that and like that bit of troubleshooting tip to have a better understanding of what's going on.
I can replace it right away just wanted to narrow down the possibilities.

Much appreciated everyone.
 

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Drivin' Maniac
2002 Grand Caravan ES 3.8L
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You do have an issue right now. Change the thermostat as noted above.

BUT

Just a word of warning:

Especially if you have rear heat, the temp DOES take a long time to reach 'normal' (which is about two needle-widths below the 9PM position on the gauge). About twice as much time or km as our other cars.

The engine has a LOT of coolant to warm up. Keep your expectations low...:)
 

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mine's been like this for years, been through many a drive wrapped up with gloves on

in 40 degree weather, the heat is great if i sit in one spot for a few minutes, if i'm driving it'll never get warm
 

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Sounds like your temperature gauge is working OK and is consistent with your lack of cabin heat. The Mechanic didn't acknowledge your temperature gauge reading for some reason.

Two questions:
1. Is your top radiator hose hot?

2. Are your radiator cooling fans running continuously?

PS: Did the Mechanic use a fail safe thermostat? If so, it has likely failed in the open position. I suspect your cooling fans are running continuously.
 

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Just some info....
For some reason I recently tested the heat output at the center vent with fan on [one down from highest setting] Vent thermometer indicated 150 degrees F. Outside temp of 30 F.
 

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Elvis,

If you got 150F, then things are probably OK, as to get 150F, your coolant had to be at least 180F.

I suggest you get a cheap infrared thermometer, measure underhood temps, and compare temps to another vehicle, that is, before your drive yourself crazy chasing temps.

Also, when you measured 150F, where was the dashboard temp gauge sitting.
 

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Elvis,

If you got 150F, then things are probably OK, as to get 150F, your coolant had to be at least 180F.

I suggest you get a cheap infrared thermometer, measure underhood temps, and compare temps to another vehicle, that is, before your drive yourself crazy chasing temps.

Also, when you measured 150F, where was the dashboard temp gauge sitting.
I am not saying I have a problem. I only posted this info as to help someone evaluate their heating system.
 

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Sounds like your temperature gauge is working OK and is consistent with your lack of cabin heat. The Mechanic didn't acknowledge your temperature gauge reading for some reason.

Two questions:
1. Is your top radiator hose hot?

2. Are your radiator cooling fans running continuously?

PS: Did the Mechanic use a fail safe thermostat? If so, it has likely failed in the open position. I suspect your cooling fans are running continuously.
I initially had these same thoughts, but decided against the theory based on the temperature gauge seemingly indicating a temperature below which the fans would normally be turned on... unless there was also a failure in the fan relay/control keeping them stuck in a running state.

Anyone know what the range of temperatures is that our dash display is actually capable of showing?
 

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my crappy mechanic (he's cheap, no wonder) and he insisted that there was nothing wrong with the thermostat as he replaced it
If your crappy mechanic replaced it with anything other than an OEM thermostat, then that was likely the mistake. I would highly recommend using only OEM thermostats in our engines.
 

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Discussion Starter #15
Here are the observations/test results:

From cold start with radiator cap removed, no coolant movement at all, dead calm.
After idling for a while the temperature get higher and the upper hose is hot to the touch.
After driving on the highway for 15 minutes or so, temperature dropped to just above the C mark, I pulled off the highway and was able to very easily touch the top hose and old down to it for as long as I wanted to.
I did not see any of the fans on at any time, not when hot and not when cold.
 

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Discussion Starter #16
If your crappy mechanic replaced it with anything other than an OEM thermostat, then that was likely the mistake. I would highly recommend using only OEM thermostats in our engines.
He's my friend and I knew him for years, he never uses anything OEM, all after market and often used.
When I called him about the problem I'm having he told me to check the coolant level and that was the first I noticed that the reservoir cover was broken and open all the time. It took about 3 litres to top off the coolant and then I duck taped it till I get a new cap.
 

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From cold start with radiator cap removed, no coolant movement at all, dead calm.
After idling for a while the temperature get higher and the upper hose is hot to the touch.
After driving on the highway for 15 minutes or so, temperature dropped to just above the C mark, I pulled off the highway and was able to very easily touch the top hose and old down to it for as long as I wanted to.
Sounds like it could be a 'sticky' t-stat, debris in the cavity preventing it from closing until it's cold and full force of spring is applied or it was not seated correctly (and 'foats' around in the cavity)...

Rad fans can run all they want, it's thermostat that controls the temperature of engine side of cooling system (we're not talking about a/c condenser here)

How often do you top it off with coolant? 3 liters is a lot of antifreeze - is the level good now (or does it leak / loose good quantity on every warm up cycle)? - Check in radiator, not in overflow tank.
 

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Engine truly seems to be running cold, which would tend to be a "stuck open" thermostat, assuming the system is filled properly. Again, highly recommend an OEM one...

As for coolant level, let the engine cool down and then crack open the radiator cap to take a look. Coolant level should not normally be very low in the radiator when opened after cool-down. If not sure then top up radiator after cooldown and let us know how much you have to put in to bring coolant level up to top of radiator.

Proper way to fill the cooling system is to completely fill the radiator first, install the radiator cap, and then top-off the overfill reservoir.

Most reliable way to check for coolant loss is at the radiator cap once the engine is cool. Watching the overflow level can be hit or miss depending on the manner in which coolant is being lost.

When running and warmed up, does the upper hose offer any resistance to being squeezed? There should be something on the order of 15 or 16 psi of pressure maintained in a fully filled and properly functioning cooling system when it is hot, so you should notice that pressure when you try to squeeze the hose. If upper hose squeezes easily with no real resistance after warm-up, then the system is not pressurized properly and you have a problem.
 

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Discussion Starter #19
When running and warmed up, does the upper hose offer any resistance be being squeezed? There should be something on the order of 15 or 16 psi of pressure maintained in a fully filled and properly functioning cooling system when it is hot, so you should notice that pressure when you try to squeeze the hose. If upper hose squeezes easily with no real resistance after warm-up, then the system is not pressurized properly and you have a problem.
The coolant level is the same since I topped it off a few days ago. I'm guessing the reason it was so low is that the reservoir cap was open or that it was not topped off properly to begin with but there are not leaks and the level is staying the same.

Yes there's pressure in the hose when it is hot, I felt it when I was testing it today.
I will pickup an OEM thermostat tomorrow and illimnate that possibiliity so I can move on with any others if the symptoms persist.
 

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Drivin' Maniac
2002 Grand Caravan ES 3.8L
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Hopefully you are determining Coolant Level by removing the radiator cap, not just looking at the expansion tank.

To assure that you have purged any air pockets in the system, warm up the engine for at least 5 minutes, then go for a ride nearby. Hold the engine in a low gear and rev it up (over 4K if you have a tachometer) a couple times.

The increased coolant velocity will purge the air.

Check the rad again COLD, for 4 - 5 drive cycles.
 
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