Coolant Leak

fzrider · 11-27-2015, 08:17 PM

My car has recently developed a coolant leak and I cannot find the leak.

It recently got cold and I noticed something wet on the floor in the garage, I didn't think anything of it since there was snow. A few days later the low coolant light came on and the heat was blowing cold. I parked and went into a store, came back an there was a small puddle of coolant on the ground.

The coolant reservoir was low and I added about a gallon of distilled water, then pressurized the system. The pressure reduced a few psi after about 15 min but did not completely depressurize.

I took off all of the underbelly plastics to see if I could find the leak, no luck. Then I ran the water pump by holding down the accelerator and heat on, still nothing.

Finding the leak is harder since I have an oil leak at the filter housing, which the dealer said they fixed at the last service.

I am frustrated because it seems that the leak is external, but cannot find the source of it. Any advice would be greatly appreciated.

agustincuenca · 11-27-2015, 08:29 PM

What can be happening is that the expansion tank gasket is gone (if inspect the expansion tank, from where you actually pour fluid, it has a division and that's where the gasket is), so what it does is that after running the car for a while getting the engine warmed up and then stopping, the pressure that it builds up in the system due to evaporation will make the fluid leak trough this gasket. If you are going to add more fluid I would go with the OEM one which is dyed so it will help you notice where the leak is and where the fluid is coming from, in addition it smells and it kinda oily to the touch.

sankohuy · 11-27-2015, 09:21 PM

I had a small leak last month and the shop couldn't find it also. They even pressure test it for leaks and could not see the leak anywhere. Until I asked them to check my lower coolant hose, turns out, they found that it was my water pump that's cracked.

fzrider · 11-27-2015, 10:37 PM

Quote:

Originally Posted by agustincuenca

What can be happening is that the expansion tank gasket is gone (if inspect the expansion tank, from where you actually pour fluid, it has a division and that's where the gasket is), so what it does is that after running the car for a while getting the engine warmed up and then stopping, the pressure that it builds up in the system due to evaporation will make the fluid leak trough this gasket. If you are going to add more fluid I would go with the OEM one which is dyed so it will help you notice where the leak is and where the fluid is coming from, in addition it smells and it kinda oily to the touch.

are you saying the expansion tank is made of two pieces and there is a gasket between the two pieces? Or are you talking about the gaskets on the expansion tank cover?

fzrider · 11-27-2015, 10:41 PM

Quote:

Originally Posted by sankohuy

I had a small leak last month and the shop couldn't find it also. They even pressure test it for leaks and could not see the leak anywhere. Until I asked them to check my lower coolant hose, turns out, they found that it was my water pump that's cracked.

I looked at the water pump and hoses going into the pump and could not see any coolant leaking. Water was flowing through the expansion tank when i manually ran the pump. So I am thinking the pump is okay.

agustincuenca · 11-27-2015, 10:45 PM

yes, it actually is. The expansion tank itself is made out of 2 pieces, but sold as one, and is where it may leak as it happened to me specially after running the car that builds up pressure which then sitting will make it fail. Unfortunately I don't have pictures now to point it out to you but I can do tomorrow, although I think it's worth looking at that piece on your situation and your given description..

fzrider · 11-27-2015, 11:28 PM

This is a very interesting idea, and very well could be the problem. How did you diagnose the expansion tank. Did you let it warm up to operating temperature and see it leaking at the seam? I was working with a cold engine so I would not have seen such a leak if it is caused by thermal expansion.

Thanks for the help

dawhiz · 11-28-2015, 01:29 AM

There is a bleed procedure to run the pump with the engine off.

Gamboa989 · 11-28-2015, 02:24 AM

Please keep us updated!! I have developed the same leak in my car about 4 days ago and it's getting worse.

I think my leak is coming from the lip on the expansion tank but I am not 100% sure.

Wires · 11-28-2015, 08:09 PM

Not sure if it's the same on these cars, but I had a similar issue on my 5.3L GM truck. It ended up being the bottom rad hose clamp (one of those clamps that you squeeze the ends with pliers, and it gets bigger).

The clamp broke, but was fused to the hose. When I grabbed it with the pliers, it split in two. Replaced it, and it was fine.

Once it got hot the pressure would blow out some coolant when I shut off the engine. Pretty frustrating since it was impossible to find.

Eagle1oh7 · 11-28-2015, 08:14 PM

When was the last time you changed out your hoses? Maybe it's your expansion tank and water pump?

hOlykamOtie* · 11-28-2015, 10:28 PM

Check radiator also. That was the part that leaked coolant on my car a month ago. My mechanic replaced it!

Eagle1oh7 · 11-28-2015, 10:46 PM

How many miles do you have anyways?

fzrider · 11-29-2015, 07:23 AM

My car has 52,000 miles so I am just out of warranty. Since I could not find the leak with the pressure test, I am thinking it may be caused by things expanding when they get warm. I am going to get the car up to operating temp and then look for the leak.

agustincuenca · 11-29-2015, 04:17 PM

Quote:

Originally Posted by fzrider

This is a very interesting idea, and very well could be the problem. How did you diagnose the expansion tank. Did you let it warm up to operating temperature and see it leaking at the seam? I was working with a cold engine so I would not have seen such a leak if it is caused by thermal expansion.

Thanks for the help

Yes, in my case, the expansion tank leaked for a while after stopping the car after running it for at least 20 minutes. So I guess, the fluid leaked until the pressure goes down. It was not a constant leak that left puddles everywhere. If you can/want go for a long drive, go back to your place and park the car with the hood open and check what happens the next minutes after stopping.

Sgop335 · 11-29-2015, 05:04 PM

Quote:

Originally Posted by fzrider

My car has 52,000 miles so I am just out of warranty. Since I could not find the leak with the pressure test, I am thinking it may be caused by things expanding when they get warm. I am going to get the car up to operating temp and then look for the leak.

My radiator drain plug had a small leak. Had to take my fmic out to spot it.

fzrider · 11-29-2015, 06:59 PM

Quote:

Originally Posted by agustincuenca

Yes, in my case, the expansion tank leaked for a while after stopping the car after running it for at least 20 minutes. So I guess, the fluid leaked until the pressure goes down. It was not a constant leak that left puddles everywhere. If you can/want go for a long drive, go back to your place and park the car with the hood open and check what happens the next minutes after stopping.

I took the car on a drive and got it up to operating temperature. I was able to see wisps of steam coming from the water pump area this time. It is also dripping from this area, but I cannot see where the leak actually is because of the tight quarters. There is a hose visible rear of the subframe that is wrapped by a heat shield the is coated with coolant.

Is it definitively the water pump, or is it something to do with the thermostat. I am wondering this because the pressure test did not reveal the leak, the leak only presented when the radiator fan ran, presumably this is when the thermostat is open and water flows through the engine.

Any ideas??

Cloudywolf · 11-30-2015, 02:26 PM

For me, my engine oil housing gasket deteriorated and the engine oil leaked into my coolant. I had to replace the expansion tank, coolant hoses, and sealant rings. I was still experiencing engine overheating issues. Like you, I was unsure if it could be either the water pump or thermo since I had replaced everything else. Ultimately I replaced both as a preventative measure

trixdout · 12-01-2015, 02:27 PM

The 2 halves where they are joined together is where I'm getting my leak. The joint is almost near the top. My tank is actually under low due to this. All that caused this was idling in my driveway for an extended period (like 30 minutes). Hasn't leaked since.

e90ca · 12-02-2015, 03:42 PM

I had a coolant leak issue as well and it turned out mine was leaking at the top of the tank near where the screws are. Replaced with a new coolant tank and the issue is gone. The tank part didn't cost much, i think it was about $60 bucks or so and just had to pay labor for the replacement and bleed procedure.

3s4u2 · 12-02-2015, 04:16 PM

I have seen a few cracked water pumps lately...

timothy2001 · 12-03-2015, 06:22 AM

My expansion tank was leaking at the seam, tough to diagnose as it was intermittent.

Replace the tank, very easy to do yourself and problem solved. Appears this is somewhat common so this is a likely source of your leak.

11-27-2015, 08:17 PM	#1
fzrider New Member 6 Rep 8 Posts Drives: 2011 335ix Space Grey Join Date: Mar 2015 Location: Salt Lake, UT iTrader: (0)	Coolant Leak My car has recently developed a coolant leak and I cannot find the leak. It recently got cold and I noticed something wet on the floor in the garage, I didn't think anything of it since there was snow. A few days later the low coolant light came on and the heat was blowing cold. I parked and went into a store, came back an there was a small puddle of coolant on the ground. The coolant reservoir was low and I added about a gallon of distilled water, then pressurized the system. The pressure reduced a few psi after about 15 min but did not completely depressurize. I took off all of the underbelly plastics to see if I could find the leak, no luck. Then I ran the water pump by holding down the accelerator and heat on, still nothing. Finding the leak is harder since I have an oil leak at the filter housing, which the dealer said they fixed at the last service. I am frustrated because it seems that the leak is external, but cannot find the source of it. Any advice would be greatly appreciated.
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11-27-2015, 08:29 PM	#2
agustincuenca First Lieutenant 154 Rep 342 Posts Drives: 2008 E90 335i; 2016 F80 M3 Join Date: Sep 2014 Location: S Louis iTrader: (0) Garage List 2016 BMW M3 [0.00] 2008 BMW 335i [0.00]	What can be happening is that the expansion tank gasket is gone (if inspect the expansion tank, from where you actually pour fluid, it has a division and that's where the gasket is), so what it does is that after running the car for a while getting the engine warmed up and then stopping, the pressure that it builds up in the system due to evaporation will make the fluid leak trough this gasket. If you are going to add more fluid I would go with the OEM one which is dyed so it will help you notice where the leak is and where the fluid is coming from, in addition it smells and it kinda oily to the touch.
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11-27-2015, 09:21 PM	#3
sankohuy First Lieutenant 44 Rep 385 Posts Drives: E92 335i Join Date: Oct 2012 Location: norcal iTrader: (0)	I had a small leak last month and the shop couldn't find it also. They even pressure test it for leaks and could not see the leak anywhere. Until I asked them to check my lower coolant hose, turns out, they found that it was my water pump that's cracked.
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11-27-2015, 10:45 PM	#6
agustincuenca First Lieutenant 154 Rep 342 Posts Drives: 2008 E90 335i; 2016 F80 M3 Join Date: Sep 2014 Location: S Louis iTrader: (0) Garage List 2016 BMW M3 [0.00] 2008 BMW 335i [0.00]	yes, it actually is. The expansion tank itself is made out of 2 pieces, but sold as one, and is where it may leak as it happened to me specially after running the car that builds up pressure which then sitting will make it fail. Unfortunately I don't have pictures now to point it out to you but I can do tomorrow, although I think it's worth looking at that piece on your situation and your given description..
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11-27-2015, 11:28 PM	#7
fzrider New Member 6 Rep 8 Posts Drives: 2011 335ix Space Grey Join Date: Mar 2015 Location: Salt Lake, UT iTrader: (0)	This is a very interesting idea, and very well could be the problem. How did you diagnose the expansion tank. Did you let it warm up to operating temperature and see it leaking at the seam? I was working with a cold engine so I would not have seen such a leak if it is caused by thermal expansion. Thanks for the help
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11-28-2015, 01:29 AM	#8
dawhiz Private 23 Rep 85 Posts Drives: 09 335xi RB/inlets/etc Join Date: Mar 2015 Location: ID iTrader: (0)	There is a bleed procedure to run the pump with the engine off.
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11-28-2015, 02:24 AM	#9
Gamboa989 Private First Class 9 Rep 106 Posts Drives: 2012 335i E92 Join Date: Nov 2012 Location: Cape Coral, Fl iTrader: (0) Garage List 2009 Bmw 328i [0.00]	Please keep us updated!! I have developed the same leak in my car about 4 days ago and it's getting worse. I think my leak is coming from the lip on the expansion tank but I am not 100% sure.
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11-28-2015, 08:09 PM	#10
Wires Brigadier General 1646 Rep 4,876 Posts Drives: 2016 340i xDrive Join Date: Apr 2008 Location: Calgary iTrader: (0)	Not sure if it's the same on these cars, but I had a similar issue on my 5.3L GM truck. It ended up being the bottom rad hose clamp (one of those clamps that you squeeze the ends with pliers, and it gets bigger). The clamp broke, but was fused to the hose. When I grabbed it with the pliers, it split in two. Replaced it, and it was fine. Once it got hot the pressure would blow out some coolant when I shut off the engine. Pretty frustrating since it was impossible to find.
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11-28-2015, 08:14 PM	#11
Eagle1oh7 Lieutenant Colonel 287 Rep 1,710 Posts Drives: '11 328i Sedan Join Date: Oct 2012 Location: Chula Vista CA iTrader: (0)	When was the last time you changed out your hoses? Maybe it's your expansion tank and water pump? __________________ DONE: Seibon CF Hood, M3 Rep, MSport rear w/DD CF Diffuser, M3 Rep Skirts, Seibon CSL trunklid, Forgestar F14 18s w/Michelin PSS, Eisenmann catback, AA Headers, BPC Stage 2, Charcoal Delete+revMotor+AFE Drop In filter FUTURE MODS: LED headlights, CF rooftop, M3 Suspension Conversion, Dinan CAI Mod
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11-28-2015, 10:28 PM	#12
hOlykamOtie* Second Lieutenant 35 Rep 263 Posts Drives: Honda Civic Join Date: Jul 2014 Location: Long Beach, CA iTrader: (1)	Check radiator also. That was the part that leaked coolant on my car a month ago. My mechanic replaced it! __________________ E90 330i \| M-Sport Conversion \| Apex ARC-8 18X9/9.5 \| General AS-05 Tires \| Koni Str.t / H&R Sport Kit \| Centric Carbon Rotors \| Akebono Ceramic Pads E82 135i \| M-Sport \| BMS DCI \| BMS Phx Racing CP \| MHI OEM Twins \| Ebay OCC \| Silicone VL \| G-Plus 5" FMIC \| Alzor Style 040 18X8/9 \| Barum Bravuris 3HM Tires
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11-28-2015, 10:46 PM	#13
Eagle1oh7 Lieutenant Colonel 287 Rep 1,710 Posts Drives: '11 328i Sedan Join Date: Oct 2012 Location: Chula Vista CA iTrader: (0)	How many miles do you have anyways? __________________ DONE: Seibon CF Hood, M3 Rep, MSport rear w/DD CF Diffuser, M3 Rep Skirts, Seibon CSL trunklid, Forgestar F14 18s w/Michelin PSS, Eisenmann catback, AA Headers, BPC Stage 2, Charcoal Delete+revMotor+AFE Drop In filter FUTURE MODS: LED headlights, CF rooftop, M3 Suspension Conversion, Dinan CAI Mod
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11-29-2015, 07:23 AM	#14
fzrider New Member 6 Rep 8 Posts Drives: 2011 335ix Space Grey Join Date: Mar 2015 Location: Salt Lake, UT iTrader: (0)	My car has 52,000 miles so I am just out of warranty. Since I could not find the leak with the pressure test, I am thinking it may be caused by things expanding when they get warm. I am going to get the car up to operating temp and then look for the leak.
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11-30-2015, 02:26 PM	#18
Cloudywolf Private First Class 15 Rep 133 Posts Drives: 2013 Z4 35i Join Date: Oct 2011 Location: Los Angeles, California iTrader: (1)	For me, my engine oil housing gasket deteriorated and the engine oil leaked into my coolant. I had to replace the expansion tank, coolant hoses, and sealant rings. I was still experiencing engine overheating issues. Like you, I was unsure if it could be either the water pump or thermo since I had replaced everything else. Ultimately I replaced both as a preventative measure
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12-01-2015, 02:27 PM	#19
trixdout Lieutenant 57 Rep 439 Posts Drives: '11 335xi 6mt Join Date: Apr 2014 Location: NNJ iTrader: (1)	The 2 halves where they are joined together is where I'm getting my leak. The joint is almost near the top. My tank is actually under low due to this. All that caused this was idling in my driveway for an extended period (like 30 minutes). Hasn't leaked since. __________________ LMB , M-Sport, JB4 Stg. 2, AR catless res. dp, ETS cp
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12-02-2015, 03:42 PM	#20
e90ca Captain 82 Rep 671 Posts Drives: 2011 335i M-Sport Join Date: Mar 2007 Location: Pleasanton, CA iTrader: (12)	I had a coolant leak issue as well and it turned out mine was leaking at the top of the tank near where the screws are. Replaced with a new coolant tank and the issue is gone. The tank part didn't cost much, i think it was about $60 bucks or so and just had to pay labor for the replacement and bleed procedure. __________________ 2011 335i with M-Sport Performance package, Carbon Fiber interior trim, gloss black kidney grills. 18" Apex Arc-8, JB4, ETS Charge pipe
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12-02-2015, 04:16 PM	#21
3s4u2 Beamer Mantic 82 Rep 1,191 Posts Drives: 2006 325i Prem Join Date: Apr 2008 Location: Texas iTrader: (0)	I have seen a few cracked water pumps lately... __________________ 2006 325i 2006 M5 2008 X5 4.8i 2014 X5 50i M-Pkg
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12-03-2015, 06:22 AM	#22
timothy2001 Major 849 Rep 1,180 Posts Drives: 2011 E92 M3 6MT ZCP Join Date: Oct 2014 Location: NE Florida iTrader: (0) Garage List 2011 M3 E92 [0.00]	My expansion tank was leaking at the seam, tough to diagnose as it was intermittent. Replace the tank, very easy to do yourself and problem solved. Appears this is somewhat common so this is a likely source of your leak.
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