6.7 cummins losing coolant, with no heat.

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.

shock

Junior Member
Joined
Nov 13, 2022
Posts
9
Reaction score
0
Location
Bg ky
Ram Year
2015
Engine
6.7 cummins
My 6.7 is losing coolant, with no visible leaks. Replace thermostat, still didn't help. Trucks runs between 188-200. Oil looks good, doesn't white smoke, pressurized the coolant system all was good, head gasket looks good. Any suggestions
 

mtnrider

Senior Member
Joined
Sep 25, 2014
Posts
3,164
Reaction score
3,406
Location
Georgia
Ram Year
2016
Engine
6.7 Cummins
How much is it losing? Head gasket, EGR, are a few things that come to mind but I wouldn't think it would pass a pressure test (may only show when it gets hot)? If it's not leaking it being burned or going in the oil, those are pretty much your choices.

Are you tuned by chance? if so that greatly increase's the chance of the head gasket going.

No heat is probably air in the heater core or it's clogged. Did it just start out of the blue?

.
 

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
thatcommentupthere.jpeg
 
OP
OP
S

shock

Junior Member
Joined
Nov 13, 2022
Posts
9
Reaction score
0
Location
Bg ky
Ram Year
2015
Engine
6.7 cummins
Truck is deleted and tuned. I don't have an egr. I add about 20oz a week. Honestly didn't really check until now. Truck doesn't run hot, it shows no symptoms of a bad hg , but then again I am not a diesel mechanic. I did notice before it got cold heater worked great when it was 80 outside now its 30 and it blows lukewarm heat
 

06 Dodge

Senior Member
Joined
Jan 4, 2022
Posts
1,900
Reaction score
1,781
Location
Forest Grove, Oregon
Ram Year
2022
Engine
6.7L CTD
What does the oil look like when you pull the dip stick? I would be pulling an oil sample and sending it out to Blackstone asap
 
OP
OP
S

shock

Junior Member
Joined
Nov 13, 2022
Posts
9
Reaction score
0
Location
Bg ky
Ram Year
2015
Engine
6.7 cummins
Oil looks good, not milky looking. Just had it serviced a month ago and all was good. Truck runs and performs like it should.
 

Hornet7

Junior Member
Joined
Sep 9, 2022
Posts
1
Reaction score
0
Location
New Mexico
Ram Year
2019
Engine
5.7 Hemi
There is a good possibility that you have a pinhole leak in the head gasket. Get a block tester, about $35 on Amazon, to find out.
 

Fuel35 67

Senior Member
Military
Joined
Aug 18, 2019
Posts
311
Reaction score
194
Location
Hanford
Ram Year
2011
Engine
6.7 Cummins
Check the overflow tank as well, they’ve been known to crack.
 

06 Dodge

Senior Member
Joined
Jan 4, 2022
Posts
1,900
Reaction score
1,781
Location
Forest Grove, Oregon
Ram Year
2022
Engine
6.7L CTD
Oil looks good, not milky looking. Just had it serviced a month ago and all was good. Truck runs and performs like it should.
I would still pull an oil sample... I just pulled an oil sample on mine today after finding the coolant about 1/2-3/4 qt low with no visible leaks, I saw no sign of coolant in the oil. As I see it the cost of a Blackstone oil analyst at $35.00 is the one of the best way to know 100% if I have coolant or fuel in the oil and it will give me a heads up if there is any internal wear problems...
 

oe542bob

Senior Member
Supporting Member
Joined
Oct 29, 2015
Posts
538
Reaction score
476
Ram Year
2022
Engine
Hemi eTorque 5.7
I went through this past summer. Can’t address the lukewarm heat issue, but in my case, I noticed my oil level had crept up. I do my own oil changes, so I knew it wasn’t overfilled.
Oil looked fine, a sample was sent to Blackstone, and it confirmed coolant in the oil.
In my case, the head gasket was replaced as well as the EGR cooler. ( Truck had around 119,000 miles and is totally stock ) It’s been perfect since late August when the work was complete.
 
OP
OP
S

shock

Junior Member
Joined
Nov 13, 2022
Posts
9
Reaction score
0
Location
Bg ky
Ram Year
2015
Engine
6.7 cummins
Problem solved. Heater core was so stopped. My diesel mechanic had to flush it out 3 times before coolant would flow like it should. Heat works great now
 

Corey_lax

Junior Member
Joined
Dec 5, 2021
Posts
5
Reaction score
1
Location
British Columbia
Ram Year
2012
Engine
6.7 Cummins
I had a leak somewhere for years, same symptoms as you. I flushed out the heater core and got it flowing again. I finally pulled the plastic piece off the top of the radiator and found a small leak at the top of the radiator. Not a big enough leak to notice anything on the ground, but enough to let air into the system obviously. New radiator installed over the weekend and I now have 140 degrees coming out the vents!
 
Top