2019 GLE400 faulty thermostat? Air in coolant?
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 42
Likes: 2
From: NJ
2011 Mercedes E550 Cabriolet Sport, 2019 GLE400 4MATIC
2019 GLE400 faulty thermostat? Air in coolant?
Good Afternoon everyone,
this may be a common question, but I do not see it on this forum for some reason. Recently I had a low coolant message on my car, I filled the coolant and the message disappeared…but It is taking very long for the car to get up to operating temperature and i am noticing gears are slipping or not shifting like normal …is this air in the coolant or is this a faulty thermostat? I only noticed one time where the gauge dipped to about 70C before coming back to temp while driving …the car runs at temp and doesn’t go above operating…but the car blows warm not hot air through the vents…I know the dealership is going to try and get me for a flush and a thermostat replacement …I want to know if this is the correct approach or if this could just be air in the line? I would appreciate any and all responses
thank you,
skbrod
this may be a common question, but I do not see it on this forum for some reason. Recently I had a low coolant message on my car, I filled the coolant and the message disappeared…but It is taking very long for the car to get up to operating temperature and i am noticing gears are slipping or not shifting like normal …is this air in the coolant or is this a faulty thermostat? I only noticed one time where the gauge dipped to about 70C before coming back to temp while driving …the car runs at temp and doesn’t go above operating…but the car blows warm not hot air through the vents…I know the dealership is going to try and get me for a flush and a thermostat replacement …I want to know if this is the correct approach or if this could just be air in the line? I would appreciate any and all responses
thank you,
skbrod
Last edited by Skbrod; Feb 19, 2025 at 01:11 PM.
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 42
Likes: 2
From: NJ
2011 Mercedes E550 Cabriolet Sport, 2019 GLE400 4MATIC
Thank you for your reply! so I took it to the dealership and they convinced me to do a diagnostic, instead of the thermostat repair... dealership told me it cant be the thermostat because car isnt registering any codes for a faulty thermostat? ...They said the hoses going in to the radiator is 180 degrees but coming out is 80 degrees...they told me it is a blockage with the silicates rupturing in my coolant system...but that would only explain the cabin temp being wrong correct? would that effect my temp gauge and performance? it still doesnt get up to temp for a while, and if I cut the heat to the cabin it still takes a while to heat up. They want to replace everything, i still think it is a thermostat issue and they're just selling me on parts and labor. What is your guess? Did mercedes really bungle this design that bad they have beads that can rupture in their tanks?
Last edited by Skbrod; Mar 3, 2025 at 02:16 PM.
MBWorld Fanatic!
Joined: Oct 2009
Posts: 7,016
Likes: 2,198
From: Colorado
'21 AMG53 wDPP & ARC, 19 GLC300 - Former-03 C240,2 ML BlueTecs,20 GLE450 E-ABC,15 Cayenne D,17 Macan
Thank you for your reply! so I took it to the dealership and they convinced me to do a diagnostic, instead of the thermostat repair... dealership told me it cant be the thermostat because car isnt registering any codes for a faulty thermostat? ...They said the hoses going in to the radiator is 180 degrees but coming out is 80 degrees...they told me it is a blockage with the silicates rupturing in my coolant system...but that would only explain the cabin temp being wrong correct? would that effect my temp gauge and performance? it still doesnt get up to temp for a while, and if I cut the heat to the cabin it still takes a while to heat up. They want to replace everything, i still think it is a thermostat issue and they're just selling me on parts and labor. What is your guess? Did mercedes really bungle this design that bad they have beads that can rupture in their tanks?
I really think you should post this in the W166 forum. There are differences.
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 42
Likes: 2
From: NJ
2011 Mercedes E550 Cabriolet Sport, 2019 GLE400 4MATIC
Thanks, i just posted in the W166. They didnt specify where the blockages are they just surmised that it cant be the thermostat because no codes and temp drop from 180 to 80. They assumed blockage but idk if that would effect performance or fuel economy either. Just drove 5 hours with it, temp gauge fluctuated down around half way then slowy climbed back to temp until i was driving for atleast 35 min, then it stablized just a hair below operating. I am going to do a coolant back flush on friday hopefully that solves my issue
Last edited by Skbrod; Mar 3, 2025 at 02:53 PM.
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 42
Likes: 2
From: NJ
2011 Mercedes E550 Cabriolet Sport, 2019 GLE400 4MATIC
Thats kinda my problem, I didn’t know exactly what was in there so I used something that looked the same , I used zerex G40 50/50 prediluded pink color to top it off, I believe they looked similar but again maybe that’s my issue and a flush will do the trick?
Trending Topics
Super Member
Joined: Jul 2021
Posts: 787
Likes: 410
From: SWFL
2024 GLE 450, 2009 SLK 300
Maybe. I think that the Zerex G40 is compatible so you should be OK. It is still odd that you had to add coolant. It had to go somewhere.
MB World Stories
The Best of Mercedes & AMG
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 42
Likes: 2
From: NJ
2011 Mercedes E550 Cabriolet Sport, 2019 GLE400 4MATIC
Last edited by Skbrod; Mar 3, 2025 at 07:26 PM.
Out Of Control!!
Joined: Sep 2018
Posts: 14,690
Likes: 4,584
From: unbegrenzt
2017 GLE350 4MATIC
Check the pressure hose at the compressor, the crimp connection weeps (leaks) with age.
When I bought a replacement hose it was the only one available in the country.
When I bought a replacement hose it was the only one available in the country.
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 42
Likes: 2
From: NJ
2011 Mercedes E550 Cabriolet Sport, 2019 GLE400 4MATIC
sorry for the late reply, finally took it in to the shop. It was a broken radiator stealing my coolant. Will get it fixed but now I have the dreaded P06DA code and I seen threads where I can unplug it so I’ll talk to them about it haha
Newbie
Joined: Dec 2025
Posts: 19
Likes: 0
W220
Good Afternoon everyone,
this may be a common question, but I do not see it on this forum for some reason. Recently I had a low coolant message on my car, I filled the coolant and the message disappeared…but It is taking very long for the car to get up to operating temperature and i am noticing gears are slipping or not shifting like normal …is this air in the coolant or is this a faulty thermostat? I only noticed one time where the gauge dipped to about 70C before coming back to temp while driving …the car runs at temp and doesn’t go above operating…but the car blows warm not hot air through the vents…I know the dealership is going to try and get me for a flush and a thermostat replacement …I want to know if this is the correct approach or if this could just be air in the line? I would appreciate any and all responses
thank you,
skbrod
this may be a common question, but I do not see it on this forum for some reason. Recently I had a low coolant message on my car, I filled the coolant and the message disappeared…but It is taking very long for the car to get up to operating temperature and i am noticing gears are slipping or not shifting like normal …is this air in the coolant or is this a faulty thermostat? I only noticed one time where the gauge dipped to about 70C before coming back to temp while driving …the car runs at temp and doesn’t go above operating…but the car blows warm not hot air through the vents…I know the dealership is going to try and get me for a flush and a thermostat replacement …I want to know if this is the correct approach or if this could just be air in the line? I would appreciate any and all responses
thank you,
skbrod
Thread Starter
Junior Member
Joined: Jun 2019
Posts: 42
Likes: 2
From: NJ
2011 Mercedes E550 Cabriolet Sport, 2019 GLE400 4MATIC
Start by inspecting the o rings on the upper and lower radiator hoses and move along inspecting your radiator system for any leaks the low coolant will cause your Mercedes Benz to overheat changing the viscosity of your engines transmission hope this helps you out
thanks my dealer showed me the cracked radiator and the spill over of coolant so I definitely need to replace that
