Coolant Leaking from under engine bay
Thread Starter
Newbie
Joined: Dec 2015
Posts: 8
Likes: 1
GL450
Coolant Leaking from under engine bay
2008 Gl450. Get a warning to top of coolant. After filling, a few minutes later, the same warning. Apparently, coolant is leaking from under the car. Enough that after refilling the reservoir; a few minutes later, another top off coolant warning.
Jacked the vehicle up this morning to determine if I locate a hose or connector gone bad. Everything in the engine bay is dry (head, radiator hoses, reservoir, both radiators).
After about 5 minutes of running the engine, a stream of fluid appeared running down towards the rear of the engine on the drivers side.
This would be just after the wheel but before the front door. The fluid is leaking off a bolt. Looks like one of the bolts for control arm. I'm assuming the source is above that but it's covered by a heat shield and parts of the frame. Can't really tell the exact source.
I read in another post that coolant from the back of the engine would indicate a heater hose. Can anyone confirm or elaborate on that? Any suggestions before I have to turn myself over top the mercy of the dealer?
Jacked the vehicle up this morning to determine if I locate a hose or connector gone bad. Everything in the engine bay is dry (head, radiator hoses, reservoir, both radiators).
After about 5 minutes of running the engine, a stream of fluid appeared running down towards the rear of the engine on the drivers side.
This would be just after the wheel but before the front door. The fluid is leaking off a bolt. Looks like one of the bolts for control arm. I'm assuming the source is above that but it's covered by a heat shield and parts of the frame. Can't really tell the exact source.
I read in another post that coolant from the back of the engine would indicate a heater hose. Can anyone confirm or elaborate on that? Any suggestions before I have to turn myself over top the mercy of the dealer?
Junior Member
Joined: Sep 2018
Posts: 22
Likes: 2
2009 GL450
2008 Gl450. Get a warning to top of coolant. After filling, a few minutes later, the same warning. Apparently, coolant is leaking from under the car. Enough that after refilling the reservoir; a few minutes later, another top off coolant warning.
Jacked the vehicle up this morning to determine if I locate a hose or connector gone bad. Everything in the engine bay is dry (head, radiator hoses, reservoir, both radiators).
After about 5 minutes of running the engine, a stream of fluid appeared running down towards the rear of the engine on the drivers side.
This would be just after the wheel but before the front door. The fluid is leaking off a bolt. Looks like one of the bolts for control arm. I'm assuming the source is above that but it's covered by a heat shield and parts of the frame. Can't really tell the exact source.
I read in another post that coolant from the back of the engine would indicate a heater hose. Can anyone confirm or elaborate on that? Any suggestions before I have to turn myself over top the mercy of the dealer?
Jacked the vehicle up this morning to determine if I locate a hose or connector gone bad. Everything in the engine bay is dry (head, radiator hoses, reservoir, both radiators).
After about 5 minutes of running the engine, a stream of fluid appeared running down towards the rear of the engine on the drivers side.
This would be just after the wheel but before the front door. The fluid is leaking off a bolt. Looks like one of the bolts for control arm. I'm assuming the source is above that but it's covered by a heat shield and parts of the frame. Can't really tell the exact source.
I read in another post that coolant from the back of the engine would indicate a heater hose. Can anyone confirm or elaborate on that? Any suggestions before I have to turn myself over top the mercy of the dealer?
Thread Starter
Newbie
Joined: Dec 2015
Posts: 8
Likes: 1
GL450
Yes it was a hose in some obscure location than you can’t to. I ended up needing a new reservoir box as well.
less than a year later the problem started again but from a different location. I was told there is a leak in the radiator.
That was after I had just spend 1100 getting the other air bag replaced. The day I got the the diagnosis of two bad rear wheel bearings and some other crazy thing in the front end.
They had their hands out looking for more 4 more grand. I took the 4 and it down on a Silverado. ✌🏿
Last edited by kware123; Oct 12, 2019 at 05:34 PM.
Newbie
Joined: Jul 2023
Posts: 8
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W220 - S430, W220 - S430, W221, S550, X164 - GL450
Yes it was a hose in some obscure location than you can’t to. I ended up needing a new reservoir box as well.
less than a year later the problem started again but from a different location. I was told there is a leak in the radiator.
That was after I had just spend 1100 getting the other air bag replaced. The day I got the the diagnosis of two bad rear wheel bearings and some other crazy thing in the front end.
They had their hands out looking for more 4 more grand. I took the 4 and it down on a Silverado. ✌🏿
less than a year later the problem started again but from a different location. I was told there is a leak in the radiator.
That was after I had just spend 1100 getting the other air bag replaced. The day I got the the diagnosis of two bad rear wheel bearings and some other crazy thing in the front end.
They had their hands out looking for more 4 more grand. I took the 4 and it down on a Silverado. ✌🏿
Newbie
Joined: Apr 2011
Posts: 10
Likes: 0
My source was the cheap plastic developing a pin hole leak right where the upper hose enters the reservoir on the drivers side. Videos I've watched to learn how to replace the radiator showed the exact same location for each one! Also, when I was under the hood I noticed the nipple on the overflow was cracked. Tried JB Weld but just didn't hold. Hope this helps!
Senior Member
Joined: May 2007
Posts: 260
Likes: 24
From: Hudson Valley, NY
2005 E55 Black, 2007 GL450 Carneol Red
2008 Gl450. Get a warning to top of coolant. After filling, a few minutes later, the same warning. Apparently, coolant is leaking from under the car. Enough that after refilling the reservoir; a few minutes later, another top off coolant warning.
...
After about 5 minutes of running the engine, a stream of fluid appeared running down towards the rear of the engine on the drivers side.
This would be just after the wheel but before the front door. The fluid is leaking off a bolt. Looks like one of the bolts for control arm. I'm assuming the source is above that but it's covered by a heat shield and parts of the frame. Can't really tell the exact source.
I read in another post that coolant from the back of the engine would indicate a heater hose. Can anyone confirm or elaborate on that? ...
...
After about 5 minutes of running the engine, a stream of fluid appeared running down towards the rear of the engine on the drivers side.
This would be just after the wheel but before the front door. The fluid is leaking off a bolt. Looks like one of the bolts for control arm. I'm assuming the source is above that but it's covered by a heat shield and parts of the frame. Can't really tell the exact source.
I read in another post that coolant from the back of the engine would indicate a heater hose. Can anyone confirm or elaborate on that? ...
I haven't identified the exact item leaking, but here's a photo of mine. (The fitting(s)/Hose with the crusty dried coolant is directly above what I believe is the Crankcase Position Sensor which is behind the black box type shield in the photo.) You can see what looks like a short heater hose with a clamp that has a small stream of coolant, and the dried coolant on the fitting(s) entering the rear of the LH cylinder head.
Any additional details and/or advice would be appreciated.
MBWorld Fanatic!
Joined: May 2015
Posts: 1,932
Likes: 291
From: Allentown, PA
'08 GL 320 CDI
If I'm reading your post correctly, you ID'd the source as a rubber hose/nipple/clamp? Good, the detective work is done. Now, the question is which of the three things it is. Does tightening the clamp fix the issue? Or possible replacing the clamp if needed. Is the hose degraded beyond use? Is the nipple cracked? Inspecting/figuring that out is your next step.
