Running hot randomly after new water pump

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Ramrob20

Junior Member
Joined
Dec 28, 2022
Posts
21
Reaction score
7
Location
Lake Tahoe
Ram Year
2014
Engine
5.7
The water pump went out 3 months ago on my 2014 Ram Hemi at about 135,000. I replaced it with a MOPAR pump, thermostat and coolant. Prior to it going, the truck would run about 199-203 and since replacing it, it runs about 204-208. And it will also randomly run all the way up to 221 until the aux fan kicks in and it comes back down.

What is making it run hotter than before?

There doesn't seem to be any air in the system, but how am I sure? I did not replace the clutch fan as it seemed to be functioning properly, could that be it?

Pic of temps from this morning.

IMG_8389.jpg
 

DILLIGAF

Senior Member
Military
Joined
May 28, 2016
Posts
4,216
Reaction score
7,551
Location
Canada
Ram Year
2012
Engine
5.7
The fan clutch should've never been put back on ;)

Might just be a slight variation from one Thermostat to the other or Still a bit of air in the system.

Burp it gain just as a precaution.
 

DILLIGAF

Senior Member
Military
Joined
May 28, 2016
Posts
4,216
Reaction score
7,551
Location
Canada
Ram Year
2012
Engine
5.7
I mean you dont need it. :headbang: :headbang: Tons of folks on here just delete it without even doing the V6 fan swap.
 

Burn2k12Ram

Senior Member
Military
Joined
May 17, 2022
Posts
582
Reaction score
839
Location
Reno, Nevada
Ram Year
2012
Engine
Hemi 5.7
What t-stat did you go with? Those have been known to be bad new. when up to temp take a temp gun and measure the temp of the top hose and bottom. Will tell you if it is opening properly or not.
 
OP
OP
R

Ramrob20

Junior Member
Joined
Dec 28, 2022
Posts
21
Reaction score
7
Location
Lake Tahoe
Ram Year
2014
Engine
5.7
What t-stat did you go with? Those have been known to be bad new. when up to temp take a temp gun and measure the temp of the top hose and bottom. Will tell you if it is opening properly or not.
It was a Mopar brand. I could try a new tstat. What should readings relatively be with a temp gun on the hoses?

EDIT: At idle and truck up to temp (203*) the top hose is ~155* and the bottom hose is ~110*
 
Last edited:

Dean2

Senior Member
Joined
Jun 17, 2021
Posts
2,718
Reaction score
3,941
Location
Near Edmonton
Ram Year
2021 2500
Engine
6.4
It was a Mopar brand. I could try a new tstat. What should readings relatively be with a temp gun on the hoses?

EDIT: At idle and truck up to temp (203*) the top hose is ~155* and the bottom hose is ~110*
Tells you the T-stat is closed at 203 or the upper hose would be 203. What does the T-stat area around the housing read before the T-stat. My 2021 2500 has a 215 Degree thermostat, actually says 102 Centigrade, so it won't normally open till the coolant hits that temp. That is without getting into the whole electronic opening stuff on them.
 
Last edited:

RedSRT4Me

Senior Member
Joined
Oct 28, 2015
Posts
2,734
Reaction score
2,086
Location
Scottsdale, Az
Ram Year
2015 CC Sport
Engine
5.7
The water pump went out 3 months ago on my 2014 Ram Hemi at about 135,000. I replaced it with a MOPAR pump, thermostat and coolant. Prior to it going, the truck would run about 199-203 and since replacing it, it runs about 204-208. And it will also randomly run all the way up to 221 until the aux fan kicks in and it comes back down.

What is making it run hotter than before?

There doesn't seem to be any air in the system, but how am I sure? I did not replace the clutch fan as it seemed to be functioning properly, could that be it?

Pic of temps from this morning.

View attachment 510063

Still have air in the system. Bleed the system and get the air out.
 

Dodge 1500 4X4

Senior Member
Supporting Member
Joined
Sep 25, 2019
Posts
2,558
Reaction score
2,219
Location
Rochester, NY
Ram Year
2019
Engine
Hemi 5.7
Remove the radiator cap and squeeze the upper hose several times, also put your heat inside truck on High to get the antifreeze to flow through heater core that may help in burping!!
 
OP
OP
R

Ramrob20

Junior Member
Joined
Dec 28, 2022
Posts
21
Reaction score
7
Location
Lake Tahoe
Ram Year
2014
Engine
5.7
Did some troubleshooting this morning. Ive determined that I don't think the thermostat is opening, let me know if you agree.

1. Confirmed no more air in system (best I could).
2. Filled reservoir tank to correct height (it was empty)
3. Let truck idle with radiator cap off and heat on.
4. Truck idled until it reached 206*

At this point the radiator overflowed out of the cap and all over the floor. The top hose measured 160*, the bottom hose was 110* and the thermostat housing was 150*.

This leads me to believe the thermostat is not opening correctly and is also probably getting stuck closed during the times it reaches 221*.

Agree?
 

danielmid

Senior Member
Supporting Member
Joined
Mar 23, 2018
Posts
1,491
Reaction score
2,647
Location
Southeast WI
Ram Year
2015 Sport 4x4
Engine
Hemi 5.7
I would tend to agree with your testing and thought process. Parts stores should have the Stant or the Gates in stock, you can drop the temp from the OEM rating as well, like the 190 or even the 180.
 

Dean2

Senior Member
Joined
Jun 17, 2021
Posts
2,718
Reaction score
3,941
Location
Near Edmonton
Ram Year
2021 2500
Engine
6.4
Did some troubleshooting this morning. Ive determined that I don't think the thermostat is opening, let me know if you agree.

1. Confirmed no more air in system (best I could).
2. Filled reservoir tank to correct height (it was empty)
3. Let truck idle with radiator cap off and heat on.
4. Truck idled until it reached 206*

At this point the radiator overflowed out of the cap and all over the floor. The top hose measured 160*, the bottom hose was 110* and the thermostat housing was 150*.

This leads me to believe the thermostat is not opening correctly and is also probably getting stuck closed during the times it reaches 221*.

Agree?
Something wrong with these numbers. 1st leave the rad cap on the radiator. The system needs pressure to operate right. If your dash is saying 206 and the thermostat housing is saying 160, what is the temp on the motor side of the thermostat, as in before the water goes through the T-stat. It should be 206 if your truck gauge is correct. If it isn't your sensor or gauge is defective.

If the Thermostat is not opening, then the Radiator should never have overflowed, otherwise where did the overflow coolant come from?

The cooling system in your truck is really pretty simple, it should not be anywhere near this difficult to figure out what is going on.

Simplified picture of how the coolant flows.

pic-8348171948286621689-1600x1200.jpg
 
OP
OP
R

Ramrob20

Junior Member
Joined
Dec 28, 2022
Posts
21
Reaction score
7
Location
Lake Tahoe
Ram Year
2014
Engine
5.7
The radiator cap was off so that any air burped when the thermostat opened. And yes I agree the thermostat did open, hadn’t had enough coffee this morning when I typed that. I guess this thermo just opens a little hotter than the other.

Still don’t know why it’s jumping up to 221* randomly when driving the same routes I always do.

Temps I took just now.

Dash reading:
9AF1F69D-26FC-4AE2-9DA8-9ACE3FA23535.jpeg

Top hose:
AAFDFD41-A576-48C7-A29B-418F6D95D7BB.jpeg

Bottom hose:
C1AC0B81-E726-4553-8FF6-4ECAA651F73A.jpeg

Thermostat:
99721FF3-CACB-4A7B-A71B-ACE5577CEEB3.jpeg

Water pump:
3E64338C-B60F-4AA7-96F8-7C69FA3096B8.jpeg
 

Attachments

  • 39FDE1DE-61E8-465C-9BE3-CD8BF191646A.jpeg
    39FDE1DE-61E8-465C-9BE3-CD8BF191646A.jpeg
    143.1 KB · Views: 6

RedSRT4Me

Senior Member
Joined
Oct 28, 2015
Posts
2,734
Reaction score
2,086
Location
Scottsdale, Az
Ram Year
2015 CC Sport
Engine
5.7
The radiator cap was off so that any air burped when the thermostat opened. And yes I agree the thermostat did open, hadn’t had enough coffee this morning when I typed that. I guess this thermo just opens a little hotter than the other.

Still don’t know why it’s jumping up to 221* randomly when driving the same routes I always do.

Temps I took just now.

Dash reading:
View attachment 510239

Top hose:
View attachment 510241

Bottom hose:
View attachment 510242

Thermostat:
View attachment 510245

Water pump:
View attachment 510246

Those temps seem normal with a stock thermostat with + or - in manufacturing tolerance. Likes other suggested you could always get another.
 

crash68

ACME product engineer
Staff member
Administrator
Supporting Member
Joined
Mar 20, 2016
Posts
10,698
Reaction score
16,705
Ram Year
2015
Engine
3.0 EcoDiesel
Using an infrared thermometer is great for reference purposes but they can be really inaccurate especially when reading through a moving air stream. Couple that with your trying to read through rubber(it's an insulator).
Stick a surface probe on the top of the thermostat housing and/or the metal part of the radiator as close to the upper hose as possible.
 

Green_Manalishi

Senior Member
Joined
May 3, 2021
Posts
161
Reaction score
209
Location
Texas
Ram Year
2017
Engine
6.7
The radiator cap was off so that any air burped when the thermostat opened. And yes I agree the thermostat did open, hadn’t had enough coffee this morning when I typed that. I guess this thermo just opens a little hotter than the other.

Still don’t know why it’s jumping up to 221* randomly when driving the same routes I always do.
You won't properly burp it with the cap off. You need to burp it a the pump. My apologies if you have already done so.
 

Dodge 1500 4X4

Senior Member
Supporting Member
Joined
Sep 25, 2019
Posts
2,558
Reaction score
2,219
Location
Rochester, NY
Ram Year
2019
Engine
Hemi 5.7
He was sitting still at idle, no air flow. Unless the fan kicks in that reading is about right.
He wasn't doing it through the air stream of the cooling fan, He still should have got a lower reading using a infrared gun, they are the most accurate, A temp prob who has time to read it!!!, also that heat at idle is the best time to check it, with no cooling going on!!!!
 

Freakydude

Senior Member
Military
Joined
Aug 20, 2022
Posts
108
Reaction score
112
Location
ontario canada
Ram Year
2018
Engine
Ecodiesel
If the air is out then I would change thermostat. Its going to be your best shot at a simple fix. could be a sensor as well?
 
Top