Low coolant warning but no leaks
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2010 E500 coupe
Low coolant warning but no leaks
Hey Guys - my first post!
Currently, I'm needing to put about 200ml of demineralized water in every 2-3 weeks (in response to a low coolant warning). Do people have any ideas as to what would be the likely cause of this coolant usage?
For background, I've done a fair bit of maintenance myself since I bought it in November but also took it into Anthony Costello Automotive (Canberra's best Merc/BMW independent specialist) to replace front/rear shocks, perform a tranny service and investigate coolant usage and a few oil leaks. $3,000 later.....
So, they replaced a few O-rings and gaskets (oil filter housing, PS reservoir) and the oil leaks appear to have been fixed. However, they discovered engine oil in the coolant expansion tank and traced it back to a leaking oil cooler. They replaced it. They reported no coolant in the transmission oil and that the head gasket(s) were ok (I have no idea how they formed that conclusion).
They performed 2 coolant pressure tests and couldn't see any leaks and I haven't seen any either. I know the Valeo radiator is quite new, as it has a manufactured in 'April 2015' sticker on it. It's not blowing any white smoke and the oil looks normal.
Any ideas - as I'm at a bit of a loss and don't really want to start randomly replacing things that may or may not fix it up.
Cheers,
Ben
Currently, I'm needing to put about 200ml of demineralized water in every 2-3 weeks (in response to a low coolant warning). Do people have any ideas as to what would be the likely cause of this coolant usage?
For background, I've done a fair bit of maintenance myself since I bought it in November but also took it into Anthony Costello Automotive (Canberra's best Merc/BMW independent specialist) to replace front/rear shocks, perform a tranny service and investigate coolant usage and a few oil leaks. $3,000 later.....
So, they replaced a few O-rings and gaskets (oil filter housing, PS reservoir) and the oil leaks appear to have been fixed. However, they discovered engine oil in the coolant expansion tank and traced it back to a leaking oil cooler. They replaced it. They reported no coolant in the transmission oil and that the head gasket(s) were ok (I have no idea how they formed that conclusion).
They performed 2 coolant pressure tests and couldn't see any leaks and I haven't seen any either. I know the Valeo radiator is quite new, as it has a manufactured in 'April 2015' sticker on it. It's not blowing any white smoke and the oil looks normal.
Any ideas - as I'm at a bit of a loss and don't really want to start randomly replacing things that may or may not fix it up.
Cheers,
Ben
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First, check the coolant reservoir. Two places it leaks is from the nipple connected to the overflow hose. The other place is the seal between the bottom (translucent) and top (black) sections. Look for any signs of coolant residue there. The other stealthy place leakcs will form is the coolant pump. It will leak behind its pulley, which will get slung by the belt and pulley and evaporate.
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2012 C300 4MATIC Sport
First, check the coolant reservoir. Two places it leaks is from the nipple connected to the overflow hose. The other place is the seal between the bottom (translucent) and top (black) sections. Look for any signs of coolant residue there. The other stealthy place leakcs will form is the coolant pump. It will leak behind its pulley, which will get slung by the belt and pulley and evaporate.
Last week, my mechanic and I pressurized the system from the water reservoir and started checking for leaks and found nothing even after removing the bottom plastic panel and getting under the car. Kindly note that the water reservoir was changed to a new one a year ago. We couldn't spot anything at all. He's saying the leak could be caused by the HVAC system where the evaporator leaks. He's saying it's a common issue with these cars.
What do you think? Anything else for me to check before replacing the evaporator? I think I should definitely have him check the coolant pump based on what you said.
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2010 E500 coupe
My car is starting to have the same problem as the OP but the warning is coming every 4-5 days. This started happening a month or two ago but it was taking longer for the warning to appear.
Last week, my mechanic and I pressurized the system from the water reservoir and started checking for leaks and found nothing even after removing the bottom plastic panel and getting under the car. Kindly note that the water reservoir was changed to a new one a year ago. We couldn't spot anything at all. He's saying the leak could be caused by the HVAC system where the evaporator leaks. He's saying it's a common issue with these cars.
What do you think? Anything else for me to check before replacing the evaporator? I think I should definitely have him check the coolant pump based on what you said.
Last week, my mechanic and I pressurized the system from the water reservoir and started checking for leaks and found nothing even after removing the bottom plastic panel and getting under the car. Kindly note that the water reservoir was changed to a new one a year ago. We couldn't spot anything at all. He's saying the leak could be caused by the HVAC system where the evaporator leaks. He's saying it's a common issue with these cars.
What do you think? Anything else for me to check before replacing the evaporator? I think I should definitely have him check the coolant pump based on what you said.
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2012 C300 4MATIC Sport
Hey ya - even though there were absolutely no visible leaks, I replaced the expansion tank with a genuine MB part and the hose that connects to the bottom of it too (A2035012682). Whilst I was there i changed the engine water pump and thermostat, which were both remarkably cheap (from FCP Euro). For good measure, I changed the $2 drain plug at the bottom of the radiator. Haven't had a problem since. Doesn't leak a drop. Good luck!
Sent the pic to my mechanic and he's is saying it's either the cooler inside the radiator or the separate oil cooler next to the oil cap since my car is european spec and has the separate cooler.
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My car is starting to have the same problem as the OP but the warning is coming every 4-5 days. This started happening a month or two ago but it was taking longer for the warning to appear.
Last week, my mechanic and I pressurized the system from the water reservoir and started checking for leaks and found nothing even after removing the bottom plastic panel and getting under the car. Kindly note that the water reservoir was changed to a new one a year ago. We couldn't spot anything at all. He's saying the leak could be caused by the HVAC system where the evaporator leaks. He's saying it's a common issue with these cars.
What do you think? Anything else for me to check before replacing the evaporator? I think I should definitely have him check the coolant pump based on what you said.
Last week, my mechanic and I pressurized the system from the water reservoir and started checking for leaks and found nothing even after removing the bottom plastic panel and getting under the car. Kindly note that the water reservoir was changed to a new one a year ago. We couldn't spot anything at all. He's saying the leak could be caused by the HVAC system where the evaporator leaks. He's saying it's a common issue with these cars.
What do you think? Anything else for me to check before replacing the evaporator? I think I should definitely have him check the coolant pump based on what you said.
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2012 C300 4MATIC Sport
I had replaced the oil cooler seals in April of 2016.
Pictures below are after a 35-minute trip this morning. I am stopping to drive the car until I take it to the garage and get it fixed.
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2010 E500 coupe
Thank you for your input. I think you did not check my latest post when you replied because it contained a picture of the engine oil cap with a milky/creamy bottom. I am sure now that the engine coolant and the engine oil are mixing. The question is whether it's because of the radiator, the oil cooler near the oil filter housing, or the head gasket. How to approach this diagnosis?
I had replaced the oil cooler seals in April of 2016.
Pictures below are after a 35-minute trip this morning. I am stopping to drive the car until I take it to the garage and get it fixed.
I had replaced the oil cooler seals in April of 2016.
Pictures below are after a 35-minute trip this morning. I am stopping to drive the car until I take it to the garage and get it fixed.
There are some other signs to look for such as excessive water/condensation from the exhaust pipe. I'm not an expert, but I don't think it can be a faulty radiator. The problem these cars have is with coolant mixing with transmission oil in the radiator although to my knowledge that was rectified in CLKs manufactured after September 2003. Having a cracked oil cooler may be the problem. Having new oil cooler seals won't necessarily matter if the structure is cracked somewhere (as mine was). Replacing the oil cooler is a cheap fix. Perhaps try that before you go doing the head gasket which will cost a bomb in labor.
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2012 C300 4MATIC Sport
Oh dear. The milky residue is generally a sign of a head gasket needing replacement There are some other signs to look for such as excessive water/condensation from the exhaust pipe. I'm not an expert, but I don't think it can be a faulty radiator. The problem these cars have is with coolant mixing with transmission oil in the radiator although to my knowledge that was rectified in CLKs manufactured after September 2003. Having a cracked oil cooler may be the problem. Having new oil cooler seals won't necessarily matter if the structure is cracked somewhere (as mine was). Replacing the oil cooler is a cheap fix. Perhaps try that before you go doing the head gasket which will cost a bomb in labor.
There are some other signs to look for such as excessive water/condensation from the exhaust pipe. I'm not an expert, but I don't think it can be a faulty radiator. The problem these cars have is with coolant mixing with transmission oil in the radiator although to my knowledge that was rectified in CLKs manufactured after September 2003. Having a cracked oil cooler may be the problem. Having new oil cooler seals won't necessarily matter if the structure is cracked somewhere (as mine was). Replacing the oil cooler is a cheap fix. Perhaps try that before you go doing the head gasket which will cost a bomb in labor.My mechanic is saying the oil cooler is the first fix to attempt since it's the cheapest and easiest just like you said. He did say that it's probably its internal structure which fails regardless of the seals. He also said that the M112/113 engines rarely ever suffer from trouble because of the head gasket so I'm just hoping it's the oil cooler. Are we able to inspect its internal when we remove it to ensure that it is indeed the problem?
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2010 E500 coupe
I've already dealt with the Valeo radiator and the ATF mixing with the coolant. Replaced the radiator with a BEHR one and did a full ATF flush along with a new filter. That was in 2014.
My mechanic is saying the oil cooler is the first fix to attempt since it's the cheapest and easiest just like you said. He did say that it's probably its internal structure which fails regardless of the seals. He also said that the M112/113 engines rarely ever suffer from trouble because of the head gasket so I'm just hoping it's the oil cooler. Are we able to inspect its internal when we remove it to ensure that it is indeed the problem?
My mechanic is saying the oil cooler is the first fix to attempt since it's the cheapest and easiest just like you said. He did say that it's probably its internal structure which fails regardless of the seals. He also said that the M112/113 engines rarely ever suffer from trouble because of the head gasket so I'm just hoping it's the oil cooler. Are we able to inspect its internal when we remove it to ensure that it is indeed the problem?
Sometimes people choose to replace the whole oil filter housing assembly the oil cooler is attached to. A replacement housing comes with a new cooler prebolted to it. It's also surpriingly inexpensive. I'd just start however with the cooler.
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Thank you for your input. I think you did not check my latest post when you replied because it contained a picture of the engine oil cap with a milky/creamy bottom. I am sure now that the engine coolant and the engine oil are mixing. The question is whether it's because of the radiator, the oil cooler near the oil filter housing, or the head gasket. How to approach this diagnosis?
Last week, my mechanic and I pressurized the system from the water reservoir and started checking for leaks and found nothing even after removing the bottom plastic panel and getting under the car. Kindly note that the water reservoir was changed to a new one a year ago. We couldn't spot anything at all. He's saying the leak could be caused by the HVAC system where the evaporator leaks. He's saying it's a common issue with these cars.
What do you think? Anything else for me to check before replacing the evaporator? I think I should definitely have him check the coolant pump based on what you said.
What do you think? Anything else for me to check before replacing the evaporator? I think I should definitely have him check the coolant pump based on what you said.
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2008 clk550 - Navigator - Frontier
Yes you can. Once it's off you should be able to see a hairline crack or other defect. However I wouldnt panic if you can't. It might just be so minute it' not visible. After you've changed out the cooler don't forget to change the oil and filter and clean up the cap. Hopefully that will be the end of the problems. Generally I agree with the mechanic that head gasket replacements are rare. The engines are pretty well designed.
Sometimes people choose to replace the whole oil filter housing assembly the oil cooler is attached to. A replacement housing comes with a new cooler prebolted to it. It's also surpriingly inexpensive. I'd just start however with the cooler.
Sometimes people choose to replace the whole oil filter housing assembly the oil cooler is attached to. A replacement housing comes with a new cooler prebolted to it. It's also surpriingly inexpensive. I'd just start however with the cooler.
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2012 C300 4MATIC Sport
Yes you can. Once it's off you should be able to see a hairline crack or other defect. However I wouldnt panic if you can't. It might just be so minute it' not visible. After you've changed out the cooler don't forget to change the oil and filter and clean up the cap. Hopefully that will be the end of the problems. Generally I agree with the mechanic that head gasket replacements are rare. The engines are pretty well designed.
Sometimes people choose to replace the whole oil filter housing assembly the oil cooler is attached to. A replacement housing comes with a new cooler prebolted to it. It's also surpriingly inexpensive. I'd just start however with the cooler.
Sometimes people choose to replace the whole oil filter housing assembly the oil cooler is attached to. A replacement housing comes with a new cooler prebolted to it. It's also surpriingly inexpensive. I'd just start however with the cooler.
Had gaskets put in my oil cooler about a year ago; took it back to the indy to replace the housing a month later. For my instance, even though the labor was minimal on the replacement, it would have been less costly to just change the housing and cooler assembly upfront. (I factor my time into the cost as well.)
Labour is pretty cheap where I live so it's not an issue. This whole thing along with the oil change will probably cost me $30 in labour. I booked an appointment with the mechanic on Saturday morning to get it fixed. I'll buy the cooler, oil, oil filter, and he'll do the labour.
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2012 C300 4MATIC Sport
So we changed the oil cooler today and cleaned the oil cap (picture attached). I separated the oil cooler from the oil filter housing, but couldn't see any defect except if I were to cut the cooler in half using a saw and I couldn't do that today. Maybe next weekend.
I'll keep cleaning the oil cap until it no longer has the milky mix.
I'll keep cleaning the oil cap until it no longer has the milky mix.
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2012 C300 4MATIC Sport
Update:
After changing the oil cooler, the car kept giving me a low coolant warning every 2-4 days and the milky stuff kept showing up on the oil cap.
This past weekend, we pressurized the system for an hour and saw the pressure decrease yet we inspected every inch of the car and the only place where we found a water leak was in the AC/Heater heat exchanger where we discovered a significant amount of water under the driver's carpet and which had leaked from the exchanger. So we replaced the exchanger and the engine oil/filter this past Saturday, but today the car gave a low coolant warning and the milky stuff is back on the oil filler cap although slightly.
I believe the worst is upon which is the head gasket. I'm honestly going to repair/replace that and sell the car as soon as I find a good W204 C-class. I've had enough with this car! So much for the robustness of the M112/722.6 package yet I keep finding myself needing to repair stuff every week or every other week. All this while I'm OCD with my car and fix things right away. I've never neglected it a single time.
After changing the oil cooler, the car kept giving me a low coolant warning every 2-4 days and the milky stuff kept showing up on the oil cap.
This past weekend, we pressurized the system for an hour and saw the pressure decrease yet we inspected every inch of the car and the only place where we found a water leak was in the AC/Heater heat exchanger where we discovered a significant amount of water under the driver's carpet and which had leaked from the exchanger. So we replaced the exchanger and the engine oil/filter this past Saturday, but today the car gave a low coolant warning and the milky stuff is back on the oil filler cap although slightly.
I believe the worst is upon which is the head gasket. I'm honestly going to repair/replace that and sell the car as soon as I find a good W204 C-class. I've had enough with this car! So much for the robustness of the M112/722.6 package yet I keep finding myself needing to repair stuff every week or every other week. All this while I'm OCD with my car and fix things right away. I've never neglected it a single time.
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Oh dear. The milky residue is generally a sign of a head gasket needing replacement There are some other signs to look for such as excessive water/condensation from the exhaust pipe. I'm not an expert, but I don't think it can be a faulty radiator. The problem these cars have is with coolant mixing with transmission oil in the radiator although to my knowledge that was rectified in CLKs manufactured after September 2003. Having a cracked oil cooler may be the problem. Having new oil cooler seals won't necessarily matter if the structure is cracked somewhere (as mine was). Replacing the oil cooler is a cheap fix. Perhaps try that before you go doing the head gasket which will cost a bomb in labor.
There are some other signs to look for such as excessive water/condensation from the exhaust pipe. I'm not an expert, but I don't think it can be a faulty radiator. The problem these cars have is with coolant mixing with transmission oil in the radiator although to my knowledge that was rectified in CLKs manufactured after September 2003. Having a cracked oil cooler may be the problem. Having new oil cooler seals won't necessarily matter if the structure is cracked somewhere (as mine was). Replacing the oil cooler is a cheap fix. Perhaps try that before you go doing the head gasket which will cost a bomb in labor.
