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Discussion Starter · #1 ·
I purchased a 2005 330i ZHP automatic with 240k miles a few months ago. It's been leaking coolant. 1 quart every 250 miles (2 weeks) of driving. Engine is not over heating. I saw the low coolant light twice and added coolant. I now add it every other day instead of waiting for the light. I did a pressure test today and there was no pressure. No smoke out of the exhaust. Replaced the cap. Looking at the temp sensor and it seems to not be leaking. Could it be a small head gasket leak? I will do the test soon. I'm debating if I should do the whole level 3 cooling refresh. A friend said it might not solve the leak issue so wait. Thoughts on next steps?
 

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2006 BMW 330CIC ZHP
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A crack on the radiator tank? Do you see any "white stain marks"? If so, that's most likely coolant leaking from somewhere.
When was last maintenance done on the cooling system?
 

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2004 330Ci 115k miles
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Find the leak first, then decide what to do. If the coolant pressure test failed then coolant is going somewhere.
Might need to pull spark plugs and check for coolant inside the cylinders.
 

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2005 330xi Auto, 2006 330ci Vert Auto
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Check for leaks under the intake manifold where the hard coolant pipes are. Look for dried coolant on the "waffle" like area behind the oil filter housing and under the intake manifold.
 

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I purchased a 2005 330i ZHP automatic with 240k miles a few months ago. It's been leaking coolant. 1 quart every 250 miles (2 weeks) of driving. Engine is not over heating. I saw the low coolant light twice and added coolant. I now add it every other day instead of waiting for the light. I did a pressure test today and there was no pressure. No smoke out of the exhaust. Replaced the cap. Looking at the temp sensor and it seems to not be leaking. Could it be a small head gasket leak? I will do the test soon. I'm debating if I should do the whole level 3 cooling refresh. A friend said it might not solve the leak issue so wait. Thoughts on next steps?
Your first spend should be a UV light and UV dye trace fluid. See below.

I doubt it is the head gasket. There are lots of possibilities before you go there.
Radiator, hoses, pump shaft seal, expansion tank, expansion tank o rings. So go for the UV dye trace.

 

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+1 on the UV dye kit and dye from Amazon..Great way to spot a hard to find leak...Make sure you buy the dye for cooling systems, not oil...
 

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I won't argue with UV recommendation but I have to think that a quart of coolant is going to leave some big tracks. Best if you can look from below too. Assuming its not the gasket for now.
 

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I purchased a 2005 330i ZHP automatic with 240k miles a few months ago. It's been leaking coolant. 1 quart every 250 miles (2 weeks) of driving. Engine is not over heating. I saw the low coolant light twice and added coolant. I now add it every other day instead of waiting for the light. I did a pressure test today and there was no pressure. No smoke out of the exhaust. Replaced the cap. Looking at the temp sensor and it seems to not be leaking. Could it be a small head gasket leak? I will do the test soon. I'm debating if I should do the whole level 3 cooling refresh. A friend said it might not solve the leak issue so wait. Thoughts on next steps?
Here's a wild idea. You are not, by any chance, filling the expansion tank up to the top are you?? Because that would be overfilling it and the overfill would
be expelled from the cap when the engine gets to normal operating temperature when the coolant has expanded. Correct coolant level is about 6 inches from the top.
 

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Here's a wild idea. You are not, by any chance, filling the expansion tank up to the top are you?? Because that would be overfilling it and the overfill would
be expelled from the cap when the engine gets to normal operating temperature when the coolant has expanded. Correct coolant level is about 6 inches from the top.
Would that explain teh low coolant light?
 

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Would that explain teh low coolant light?
That might actually be caused by faulty level sensor. There's also the fact that quite a few people, myself included, have this intermittent coolant light problem
even after cooling system refresh including new sensor. I have my theories about that but it doesn't necessarily mean these things are related in the OP's case.
 

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Discussion Starter · #13 ·
A crack on the radiator tank? Do you see any "white stain marks"? If so, that's most likely coolant leaking from somewhere.
When was last maintenance done on the cooling system?
I see white stains. Don’t see a crack but will look again. I purchased the car from a seller who bought it at an auction. Carfax shows last time at a dealership 7 years ago.
 

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I see white stains. Don’t see a crack but will look again. I purchased the car from a seller who bought it at an auction. Carfax shows last time at a dealership 7 years ago.
Go for the UV. That way you will be able to see the latest stains. Distinguish new from old.
 

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Discussion Starter · #15 · (Edited)
I wait until the morning to pour the coolant. Almost near the maximum of the level sensor, so the floater is a bit over the top . When I did the pressure test, it wasn’t holding pressure. Maybe user error. I took these pictures. Don’t know the age of these. I’ve been pouring blue coolant but the stuff looks green. I’ll clean up the area. Try to do another pressure test. Question: would a level 3 refresh fix any and all possible leaks?
 

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When I did the pressure test, it wasn’t holding pressure. Maybe user error.
Nobody but only you can tell this. Learn to use the tester and the pressure should be above 15 psi at least when pumping the tool. At this pressure you should be able to see coolant drip out.
 

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I wait until the morning to pour the coolant. Almost near the maximum of the level sensor, so the floater is a bit over the top . When I did the pressure test, it wasn’t holding pressure. Maybe user error. I took these pictures. Don’t know the age of these. I’ve been pouring blue coolant but the stuff looks green. I’ll clean up the area. Try to do another pressure test. Question: would a level 3 refresh fix any and all possible leaks?
Honestly. Stop thinking about spending money until you have found the source. Just buy the UV kit. Make sure your system isn't overfilled and take it for a run. Use the lamp to see where it is leaking from.
 

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The UV test would be good, but I personally don't like dye if I can find the leak by doing some spot checks.

Do you recall the car starting up/driving with white smoke coming from the exhaust?

Do you have a cracked expansion tank? Look at this video for doing a pressure leak test. It's one of many 50skid videos.
 

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If those are drops of coolant, you have a good leak going. What does it look like from above? I'm thinking cracked tank or rad.
 

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Given the high amount of coolant stains on the left front side of the engine it's likely three things:

Expansion tank/radiator.
Radiator hose.
Coolant pipe (for the heater) under the intake manifold.

Pressure test, be patient and use a strong flashlight. Follow the wet trail upwards.
 
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