Coolant leak, but from where?
Thread Starter
Senior Member
Joined: Mar 2018
Posts: 356
Likes: 76
From: Elizabethtown Kentucky
2019 E 300 4matic 2013 SLK 250
Coolant leak, but from where?
On my 2008 E320 BlueTEC I’m having (among other things!) a coolant leak that my mechanic can’t find. He checked the engine over visually and then did a pressure test (for an hour) and couldn’t find anything. The pressure test he said held for an hour before he disconnected the tester. I can smell coolant from the far side vents when the car is started and then occasionally while driving. At first (after having owned a W140 with a leaky evaporator) I tried setting the heater on full blast hot but it doesn’t make it worse or better.
Its going to the dealership tomorrow to try to try to pin down an engine vibration that no one else has been able to fix so I guess I’ll have them check this too. I just want to be prepared for needing the defibrillator and oxygen tank.
Any ideas???
Its going to the dealership tomorrow to try to try to pin down an engine vibration that no one else has been able to fix so I guess I’ll have them check this too. I just want to be prepared for needing the defibrillator and oxygen tank.
Any ideas???
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Joined: Jan 2009
Posts: 9,224
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From: V E G A S
1922 Ford Model T / no OBD
Water pump can do trick like that.
They have ceramic seal that can hold on stop engine, but leak when turning.
Take phone camera and with front cover removed stick it under the pump. Pump is having seep hole, that will show fresh wash if my guess is correct.
They have ceramic seal that can hold on stop engine, but leak when turning.
Take phone camera and with front cover removed stick it under the pump. Pump is having seep hole, that will show fresh wash if my guess is correct.
Thread Starter
Senior Member
Joined: Mar 2018
Posts: 356
Likes: 76
From: Elizabethtown Kentucky
2019 E 300 4matic 2013 SLK 250
No problem found
well they drove the car for an hour and said they didn’t find anything abnormal other than the idle is a little high. “All diesels vibrate”
theyre looking at the coolant problem now.
theyre looking at the coolant problem now.
Thread Starter
Senior Member
Joined: Mar 2018
Posts: 356
Likes: 76
From: Elizabethtown Kentucky
2019 E 300 4matic 2013 SLK 250
no problem found
Well as you predicted Kajtek1 the dealer called this morning.
Engine vibration-within normal specs, no problem found
coolant leak-pressure tested overnight, did visual inspection. No problem found
maybe I need to take the bus and see a shrink
Engine vibration-within normal specs, no problem found
coolant leak-pressure tested overnight, did visual inspection. No problem found
maybe I need to take the bus and see a shrink
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,224
Likes: 1,798
From: V E G A S
1922 Ford Model T / no OBD
I was trying to open Mercedes Anonymous on other forum but it did not work 
So how do you measure loosing coolant?
Did dealer charge you for no-diagnosis diagnosis?
Take the darn picture.
So how do you measure loosing coolant?
Did dealer charge you for no-diagnosis diagnosis?
Take the darn picture.
Thread Starter
Senior Member
Joined: Mar 2018
Posts: 356
Likes: 76
From: Elizabethtown Kentucky
2019 E 300 4matic 2013 SLK 250
every month i have to fill up the coolant reservoir about a cup. They did replace the radiator cap because they said that the one that was on it (that I bought from them last month!) was defective so they replaced that free of charge. The bill was $42.50
They did say that the vibration may be more “heard than felt” because someone removed the anti noise panels from under the engine bay and they suggested that they be replaced. Would you go ahead and replace them?
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MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,224
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From: V E G A S
1922 Ford Model T / no OBD
Easy thing you can do is feel the hoses right after the drive. Careful as they will be hot.
Cap is at least 15psi rated, so the hoses suppose to feel hard. If you feel them soft, your cap is not holding.
Other thing is add dye to coolant and check it after few days. I am using "black light" flashlight to hunt scorpions and amazing how the light can make fluorescing items very visible.
For engine vibration, what MM and how old you have?
I install rebuild engine in my 320 BT and 1 cylinder shows weaker than others, so I do have vibration.
But having less than 20k miles on Lemforder MM, I replaced. them with Febi and most of the vibration is gone. Transmission mount did look good, so I left it, but might do it next.
Cap is at least 15psi rated, so the hoses suppose to feel hard. If you feel them soft, your cap is not holding.
Other thing is add dye to coolant and check it after few days. I am using "black light" flashlight to hunt scorpions and amazing how the light can make fluorescing items very visible.
For engine vibration, what MM and how old you have?
I install rebuild engine in my 320 BT and 1 cylinder shows weaker than others, so I do have vibration.
But having less than 20k miles on Lemforder MM, I replaced. them with Febi and most of the vibration is gone. Transmission mount did look good, so I left it, but might do it next.
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Thread Starter
Senior Member
Joined: Mar 2018
Posts: 356
Likes: 76
From: Elizabethtown Kentucky
2019 E 300 4matic 2013 SLK 250
Easy thing you can do is feel the hoses right after the drive. Careful as they will be hot.
Cap is at least 15psi rated, so the hoses suppose to feel hard. If you feel them soft, your cap is not holding.
Other thing is add dye to coolant and check it after few days. I am using "black light" flashlight to hunt scorpions and amazing how the light can make fluorescing items very visible.
For engine vibration, what MM and how old you have?
I install rebuild engine in my 320 BT and 1 cylinder shows weaker than others, so I do have vibration.
But having less than 20k miles on Lemforder MM, I replaced. them with Febi and most of the vibration is gone. Transmission mount did look good, so I left it, but might do it next.
Cap is at least 15psi rated, so the hoses suppose to feel hard. If you feel them soft, your cap is not holding.
Other thing is add dye to coolant and check it after few days. I am using "black light" flashlight to hunt scorpions and amazing how the light can make fluorescing items very visible.
For engine vibration, what MM and how old you have?
I install rebuild engine in my 320 BT and 1 cylinder shows weaker than others, so I do have vibration.
But having less than 20k miles on Lemforder MM, I replaced. them with Febi and most of the vibration is gone. Transmission mount did look good, so I left it, but might do it next.
The motor mounts and transmission mount were replaced about a month ago but even just after the replacement I couldn’t tell any difference.
Newbie
Joined: Nov 2017
Posts: 12
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From: Albania
W203 C30, W210 290TD
I was having pretty much the same problem with my W203 C30 I was losing coolant but no visible leaks anywhere except some humidity around the cap and the hoses were very hard after driving bo no overheating temperature was normal even when going up the mountain roads.
I replaced the cap thinking it was just old age and the thing gave up but with the same result still losing coolant but now I could see puddles on the ground but still no visible signs of leaking in the bay. After taking it apart I found a very tiny leak in the EGR cooling core that was leaking a very small amount of exhaust gas in the cooling system causing the pressure to raise and the cap to open allowing the coolant to escape. In addition, I decided to open the cylinder head as well to inspect the head gasket just to be sure that the problem was solved permanently and found also a very tiny crack in the head gasket and replaced that as well. Now its all sorted and the car is almost ready for the road again.
I did take my car to the repair shop to have the cooling system tested and it passed all the tests they ran on it but there was clearly a problem.
I hope this helps, this was my experience with invisible coolant leaks.
I replaced the cap thinking it was just old age and the thing gave up but with the same result still losing coolant but now I could see puddles on the ground but still no visible signs of leaking in the bay. After taking it apart I found a very tiny leak in the EGR cooling core that was leaking a very small amount of exhaust gas in the cooling system causing the pressure to raise and the cap to open allowing the coolant to escape. In addition, I decided to open the cylinder head as well to inspect the head gasket just to be sure that the problem was solved permanently and found also a very tiny crack in the head gasket and replaced that as well. Now its all sorted and the car is almost ready for the road again.
I did take my car to the repair shop to have the cooling system tested and it passed all the tests they ran on it but there was clearly a problem.
I hope this helps, this was my experience with invisible coolant leaks.
Thread Starter
Senior Member
Joined: Mar 2018
Posts: 356
Likes: 76
From: Elizabethtown Kentucky
2019 E 300 4matic 2013 SLK 250
I was having pretty much the same problem with my W203 C30 I was losing coolant but no visible leaks anywhere except some humidity around the cap and the hoses were very hard after driving bo no overheating temperature was normal even when going up the mountain roads.
I replaced the cap thinking it was just old age and the thing gave up but with the same result still losing coolant but now I could see puddles on the ground but still no visible signs of leaking in the bay. After taking it apart I found a very tiny leak in the EGR cooling core that was leaking a very small amount of exhaust gas in the cooling system causing the pressure to raise and the cap to open allowing the coolant to escape. In addition, I decided to open the cylinder head as well to inspect the head gasket just to be sure that the problem was solved permanently and found also a very tiny crack in the head gasket and replaced that as well. Now its all sorted and the car is almost ready for the road again.
I did take my car to the repair shop to have the cooling system tested and it passed all the tests they ran on it but there was clearly a problem.
I hope this helps, this was my experience with invisible coolant leaks.
I replaced the cap thinking it was just old age and the thing gave up but with the same result still losing coolant but now I could see puddles on the ground but still no visible signs of leaking in the bay. After taking it apart I found a very tiny leak in the EGR cooling core that was leaking a very small amount of exhaust gas in the cooling system causing the pressure to raise and the cap to open allowing the coolant to escape. In addition, I decided to open the cylinder head as well to inspect the head gasket just to be sure that the problem was solved permanently and found also a very tiny crack in the head gasket and replaced that as well. Now its all sorted and the car is almost ready for the road again.
I did take my car to the repair shop to have the cooling system tested and it passed all the tests they ran on it but there was clearly a problem.
I hope this helps, this was my experience with invisible coolant leaks.
Thanks for telling me but I’ve just about decided to get rid of it. Too many extremely expensive problems in too short a time.
I hear a new Lincoln Continental calling my name
