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Engine wont raise to operating temperature, and heater luke warm

21K views 54 replies 15 participants last post by  joeBlow 
#1 · (Edited)
Hello all,
I have a 2010 with the 3.8L
My issue is that the engine temperature will not raise to operating temperature. If I let it sit and idle, EVENTUALLY it will raise close to 200. but while driving, it only gets to about 160. it fluctuates some, occasionally rising slightly higher than that, but also often dropping even lower than that! The reason this bothers me, is because I know enough to know that the engine operates best at its proper operating temperature. but also because now that winter is here, my heat inside is also not as hot as it should be. it do have SOME heat, even probably good enough for me to not complain, but not good enough for my wife, haha! I am almost certain that the lack of heat inside is because of the operating temperature of the engine, because when i do let it idle and warm up all the way, the heat inside does get MUCH hotter!

I have replaced the thermostat, but that didnt change anything. I did some research and found that people talk about the radiator cap not holding pressure. but wouldnt this cause coolant to overflow into the reservoir? - I do not have that issue. people talk about the plastic valves before the heater cores, mine are find and not leaking. If i had restrictions someplace, or low coolant (which ive checked, and I dont have low coolant) wouldnt that cause overheating? not under heating? i thought maybe restriction in heater core...but like i said, if i can manage to get the engine up to temperature, interior heat temp rises right up with it. So I am a little puzzled. anybody have any ideas as to what this could be? Seen issues like this before?

Thanks for all the help!
 
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#3 ·
Welcome.

One problem with those engines is low coolant level.

If you know for sure you have a good thermostat, remove radiator cap, start engine, add coolant all the way to the top and wait until thermostat opens.

Add more coolant as needed and reinstall the radiator cap.

With radiator cap off, I believe you should be able to see coolant level.

If thermostat is open, yoy should be able to see coolant moving. If engine is cold and you see coolant moving, then thermostat is open when it shouldn't.
 
#4 ·
Thank you guys for your help. If the new thermostat is defective, I just find it odd that the same exact symptoms persist, no change at all. defective thermostat is common?

Yes I have done this with the coolant, I have a burp funnel for coolant, and let it run and fill it up, and let it run until all the air is out. The radiator cap position is offset from the top of the radiator, so I dont think I will be able to see coolant flow? but I will check
 
#5 ·
Sounds like either defective thermostat that's stuck open or air in the system. If you can, park nose up on a steep hill and repeat the burping procedure.

If coolant level drops after it's fully burped and no leaks can be found, it's possible that your head or lower intake gasket may have a leak that is burning the coolant.

Other things to check is if the fans are running constantly. Make sure A/C is off too, because that will cause the fans to run all the time.
 
#6 ·
Sounds like either defective thermostat that's stuck open or air in the system. If you can, park nose up on a steep hill and repeat the burping procedure.

If coolant level drops after it's fully burped and no leaks can be found, it's possible that your head or lower intake gasket may have a leak that is burning the coolant.

Other things to check is if the fans are running constantly. Make sure A/C is off too, because that will cause the fans to run all the time.
Absolutely not necessary.
 
#7 ·
I hope you aren't using "fail safe" thermostats, as they can be troublesome.

You provided great information and have taken a logical path to diagnosing the problem. Thanks.

The cooling fans being on too much seems to be the only other thing to check. If circulation were bad, you would have overheating. Air in the system shouldn't be a problem, never has been for me, some people seem to go through hoops trying to get air (real or imaginary) out. Just drive the vehicle and top it up a couple of times.

Low heat in the cabin can be caused by low coolant in the radiator (not reservoir). It gets better going up hill.
 
#8 ·
I made a video on how to test a thermostat years ago. I don't trust new ones from the autoparts stores, and I like to make sure that it was actually bad.
 
#11 · (Edited)
That's the way to test a thermostat, however, thermostats are very inexpensive, if you removed your thermostat already, just install a new one.

Yes, new thermostat might fail, but not very likely.

And, as Jeepman already said, Failsafe thermostats are safe to fail.

Stay away from Failsafe thermostats.
 
#9 ·
Ok I can pull the thermostat out again when I get a chance and test it. Have never really experienced bad thermostats out of the box before.

Cooling fans NEVER come on as it never reaches operating temperature haha! So they are probably working fine, simply that the pcm is not calling for them to come on.

I also do not suspect low coolant. But I will check again. usually low coolant will cause the hvac heat to be low, but when on the gas pedal it will raise the temperature. I do not have any of that. hvac temperature is very steady, but the temperature seems to be directly related to the operating temperature of the engine. Also, in my experience, low coolant also causes the temperatures to over heat..then drop back down again as the air moves around. my temperature fluctuates some, but very gradually, and NEVER over heat.

I do see some leakage (moist gunk build-up, mostly, no rapid coolant loss) around the lower intake manifold...they might need to be changed. I see a little oil leakage that is possibly around the head gaskets. But I have zero other symptoms to indicate that either of those is an imminent threat right now, fluids are not mixing, no over heating, no running issues, no smoke, and no loss of coolant, as stated before, and no loss of oil.

I need to drive it a couple hours tonight, and wont get to it much over the weekend. I have been driving it for many months like this (since i bought it) so I am not afraid to drive it, - OVERheating is the bigger issue, which is not my case. just now that winter is upon us I am realizing i might like to get to the bottom of the issue haha! maybe monday I will have time take the thermostat out and test it in that way. I used napa thermostat, Part# 195656

Thank you guys for all your responses!
 
#10 ·
I'm not sure if this is relevant to the 5th Gen, but on the 3rd gen the temperature gauge isn't specifically required to stay at the halfway mark, though it usually does. As long as it is 1/4 to 3/4, it is within "normal" range.


60290
 

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#15 ·
As far as I know Motorad is the only company that makes failsafe thermostats. The one you got from NAPA doesn't appear to be one.
 
#17 ·
#19 ·
I forgot to add. The NAPA thermostat, per your link, looks identical to the Motorad OE Standard, which in turn looks a lot like the Motorad Fail Safe. Could be a mix-up.

I would go with a Stant normally.
 
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#21 ·
Ok sorry to be absent for so long.

I drove it quite a bit this weekend. again, while driving it highway speed, it never got hotter than 3/4 of what it should be (so never got hotter than 180 deg), and often cooled down to 160, and back up again - slow changes, not drastic. at idle, it still seems to rise eventually (i feel like with the new thermostat it does not take quite as long to rise at idle as it used to). I am also noting that warm-up takes longer than I think it should. If it get in the car and start it and go right away, it will take quite a few minutes to have any significant rise in temperature.

that is not the price that I paid for the thermostat, just the first site that I found where I could share the link here lol.

I hope to be able to take the thermostat out again in the next couple days and test it, just to make sure that I dont have a faulty one.
 
#29 · (Edited)
Ok sorry to be absent for so long.

I drove it quite a bit this weekend. again, while driving it highway speed, it never got hotter than 3/4 of what it should be (so never got hotter than 180 deg), and often cooled down to 160, and back up again - slow changes, not drastic. at idle, it still seems to rise eventually (i feel like with the new thermostat it does not take quite as long to rise at idle as it used to). I am also noting that warm-up takes longer than I think it should. If it get in the car and start it and go right away, it will take quite a few minutes to have any significant rise in temperature.

that is not the price that I paid for the thermostat, just the first site that I found where I could share the link here lol.

I hope to be able to take the thermostat out again in the next couple days and test it, just to make sure that I dont have a faulty one.
It's possible the t stat has failed, but not very likely. I've probably replaced 4 in many millions of miles and 50 years of driving older vehicles.
It is very easy to quickly assess if the T stat is working normally: Cold engine, start it up and see if the top rad hose warms slowly or not. If it stays cold(er) for at least 5 min and then suddenly warms the T stat has opened as expected. If it gradually warms up but takes forever to get hot then the t stat is failed open.
I don't know what your climate is like but in the winter my fans never come on if the van is moving at any speed. They are pretty much designed to boost cooling if the a/c is employed or if you are moving slowly and the flow through the rad, air and coolant is too slow. Taking it out before diagnosing is just a waste of time and resources.
 
#22 ·
The vans warm up slowly in cold weather, takes about 5 minutes to feel any beneficial heat. The Owner Manual actually says not to use high fan speed during that time. Automatic temperature Control systems operate that way as well.
 
#23 ·
If it is very cold, I would warm the engine for maybe a minute before driving off.
Then run the vehicle in L until it heats up. Doesn't just help the engine heat up a little quicker, it keeps the transmission from shifting. Not saying the cold is bad for the transmission, but being closer to operating temperature when shifting would certainly be beneficial in the long run.


As for the gauge, I've posted this before
60338

60339


The van isn't necessarily supposed to be exactly in the middle of the gauge.
I have replaced bad coolant temperature sensors before. You used to be able to measure resistance between the style that had two pins. Since the ECU, instrument cluster, and fan relay are likely pulling data off the same sensor, it's possible that it is a three wire are resistance might be useless.
My van was always showing overheating until I replaced it. It was reading maybe 30°F high if I had to guess.
 
#24 ·
no, not that cold. like 40 degrees? and im talking longer than 5 minutes. without the heat fan on at all. ive driven many different vehicles in my life, and have worked on vehicles a lot. this one is def heating slower than it should, and not getting as hot as it should.

Special Edy, I saw your post before. my van is newer and displays the actual temperature. 200 degrees is the "middle" of the gauge. with a 195 degree thermostat, it should be close to that, not down around 160, sometimes even lower. when the temp gauge is low, the heater temperature is lower. when its higher (closer to normal position) the heater temp is higher as well. directly related to the temp of the engine, that is why I think the temp sensor is probably accurate.
 
#26 ·
Yes, the transmission's electronics takes care of the cold weather shifting by delaying shifts and lockup, depending on coolant temperatures, from which they estimate transmission fluid temperatures.

Q: The automatic transmission in my Jeep Grand Cherokee shifts differently when the weather turns cold. Is this normal?
 
#27 ·
In my experience, the thermostats in the 3.6 fail at around 90,000 miles. I have had to replace the thermostats in both my Town & Country and 300 with the 3.6 with that appox. mileage. Thankfully, both units failed in open position. Because the vehicles were not reaching proper operating temperature, they triggered the check engine light with the low operating temperature code. I recommend using only Mopar thermostats because the units come with the thermostat, the housing and the gasket. I would be weary using aftermarket units from parts stores. Mopar units are available from your dealer and sellers on eBay for under $15.00 and if you know what your doing, they can be replaced in 15 minutes.
 
#28 ·
I also endorse the Mopar part. My mechanic found out the hard way. Any other I wouldn't waste my money on. Mine had 94000 miles when I bought it in AZ and drove it back to Wi last January in some awful weather and the closer we got to home the colder the van ran. I had the AZ antifreeze flushed and a new thermostat installed but it was just as bad as the old one so the mechanic when to the local Chrysler dealer and got a Mopar stat and all was then good.
 
#31 ·
Hello all,
I have a 2010 with the 3.8L
My issue is that the engine temperature will not raise to operating temperature. If I let it sit and idle, EVENTUALLY it will raise close to 200. but while driving, it only gets to about 160. it fluctuates some, occasionally rising slightly higher than that, but also often dropping even lower than that! The reason this bothers me, is because I know enough to know that the engine operates best at its proper operating temperature. but also because now that winter is here, my heat inside is also not as hot as it should be. it do have SOME heat, even probably good enough for me to not complain, but not good enough for my wife, haha! I am almost certain that the lack of heat inside is because of the operating temperature of the engine, because when i do let it idle and warm up all the way, the heat inside does get MUCH hotter!

I have replaced the thermostat, but that didnt change anything. I did some research and found that people talk about the radiator cap not holding pressure. but wouldnt this cause coolant to overflow into the reservoir? - I do not have that issue. people talk about the plastic valves before the heater cores, mine are find and not leaking. If i had restrictions someplace, or low coolant (which ive checked, and I dont have low coolant) wouldnt that cause overheating? not under heating? i thought maybe restriction in heater core...but like i said, if i can manage to get the engine up to temperature, interior heat temp rises right up with it. So I am a little puzzled. anybody have any ideas as to what this could be? Seen issues like this before?

Thanks for all the help!

I had this same problem, and eventually realized I was leaking antifreeze from the rear heater hose above the wheel well. It was a very small leak, but over time, it lowered the anti freeze level enough to where it the heat would not be hot enough.

Just providing my 2 cents/ feedback

My second though is maybe the wrong anti freeze was used in the vehicle?
 
#32 · (Edited)
Ok, sorry to be a way so long, bringing this back now. I literally never even had a chance to take out the thermostat and test it until now, things have literally been crazy. But just to reiterate how this is DEFINITELY not a normal condition, now that its been getting colder, the problem has been even worse. if its in the 20's outside, I can drive my car for 10 miles before it even reaches 140 degrees on gauge..and definitely no heat like there should be. i understand that this really SHOULD just be a bad thermostat, i couldnt think of any other issues that would cause a car to underheat....maybe a water pump that is working too well? HAHA! but i just didnt assume that because, 1.) i changed the thermostat, 2.) the symptoms didnt change a single bit after swaping the thermostat 3.) ive never gotten a bad thermostat before.

BUT, after testing the thermostat, I do suspect it to be the issue. Actually, it seems to open and close at the right temperature just fine. But, if i put water droplets on top of it while its closed, they drip through. the opening is not visible to the naked eye, but its obviously there, and i am guessing under pressure it will probably force quite a bit of coolant through? does this seem like the culprit? a closed thermostat should let ZERO water drip through, correct?

Also, sort of funny/ironic, the thermostat I got IS made my MotoRad! it is not a failsafe, but you guys all seem to think motorad is junk, yea?

So regardless I will probably try a new thermostat anyway. so curious, thermostat choices 1.) NAPA PREMIUM ($23) (as opposed to the cheaper one i got the first time, which ended up being MotoRad - I am sure the premium is re-branded as well, but at least it doesnt say motorad on it, I think its STANDARD?) 2.) STANT OEM TYPE ($7) 3.) STANT SUPERSTAT ($8) 4.) DURALAST ($14)

Thoughts? Thanks guys!
 
#36 ·
You could also fasten a shroud over a portion of the radiator, like maybe the left half or right half.
We never have to do this in Texas, but i recall seeing trucks with louvers or shutters. I think maybe Ford pickups come with automated shutters?
 
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#33 ·
#34 ·
Superstar is Interesting as in, I should go with that one, or your not too sure? Lol.

after reading it, I feel like the regular one is prob better for me, since I’m already having problems with warMing up. Says it slowly opens to let coolant slowly through. Idk, not too sure. Maybe I’m wrong lol
 
#35 ·
Yes, the concept sounds good but simpler is probably better in your situation. đź‘Ť
 
#37 ·
thermostat was the culprit. replaced it and it warms right up now! very surprised, never seen a bad thermostat out of the box. and it was so strange because the symptoms didnt change one bit, so both thermostats must have been defective in the same exact way! so weird. anyways. I think I will aim for Stants in the future. Thank you guys for all your help! Have a Merry Christmas!
 
#45 ·
So I was having the exact same problem. New thermostats that didn’t change anything. I thought maybe that’s how these vans are till I found this forum. Decided to try one more thermostat, using the suggested Stant brand, and it worked! Thanks for the thread. I won’t buy a MotoRad from Advanced Auto ever again.
 
#40 ·
At least some Ram 1500s, Chrysler 200s, and Dodge Darts have/had active shutters.
 
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