Cooling leak dilemma

[///BMW Junkie]

1) I got code that my charge cooler pump is running dry. Checked charge cooler expansion tank and it was very low so I topped it off

2) Checked after a few days, and it was low again. This time also checked the main expansion tank and it was low as well

3) Took the car to the dealer, it's passed the pressure test and was told there is a very small leak within the charge cooler (l did my research before going in and lots of leaking coolers came up. I mentioned this to the dealer since I was not seeing any coolant on the floor or engine bay)

4) Here's where it gets interesting. It's been about a month and a few hundred miles since I took the car home. I ordered a CSF cooler which I haven't installed yet. Reason being is during this time, the charge cooler tank has remained at the same level, and the main expansion tank is still continuously dropping.

If my charge cooler is leaking, would it have an effect on the main expansion tank? I thought they are separate systems.

[damageprone]

They found that it was leaking and didn't replace it for you? Are you no longer under warranty? This has been a well documented issue and should be replaced if still under warranty.

[///BMW Junkie]

Originally Posted by damageprone

They found that it was leaking and didn't replace it for you? Are you no longer under warranty? This has been a well documented issue and should be replaced if still under warranty.

Out of warranty @ 53K miles.

[Poiseuille]

you said in your OP that you did some research into i-tank issues and disappearing coolant. did you run across the expression 'hydrolock' when you did that?
anyway, you need to change out that tank ASAP before you bend a rod, or worse.
also, the dealer who let you out the door knowing that tank was leaking is a cannibal. please go somewhere else for service/repairs.
good luck.

[///BMW Junkie]

Originally Posted by Poiseuille

you said in your OP that you did some research into i-tank issues and disappearing coolant. did you run across the expression 'hydrolock' when you did that?
anyway, you need to change out that tank ASAP before you bend a rod, or worse.
also, the dealer who let you out the door knowing that tank was leaking is a cannibal. please go somewhere else for service/repairs.
good luck.

By i-tank you're referring to the main expansion tank?

[Poiseuille]

Originally Posted by ///FastEuro

By i-tank you're referring to the main expansion tank?

sorry about the sloppy marker==>

[Poiseuille]

just now noticed a word in my post which is confusing: in the second paragraph the word 'tank' should have been intercooler. The small tank at the back of the actual intercooler is where you check for coolant level. in your OP you mentioned that your dealer told you that the leak was within the intercooler itself.

[///BMW Junkie]

I'm starting to feel my car was perhaps misdiagnosed and the charge cooler is fine as it's holding fluid. My main expansion tank on the other hand looks like this. Thoughts?

[///BMW Junkie]

Originally Posted by Poiseuille

just now noticed a word in my post which is confusing: in the second paragraph the word 'tank' should have been intercooler. The small tank at the back of the actual intercooler is where you check for coolant level. in your OP you mentioned that your dealer told you that the leak was within the intercooler itself.

Gotcha, thanks for clarifying. Please see my latest post. Thoughts?

[Poiseuille]

Originally Posted by ///FastEuro

I'm starting to feel my car was perhaps misdiagnosed and the charge cooler is fine as it's holding fluid. My main expansion tank on the other hand looks like this. Thoughts?

the white powder is from evaporated coolant, so it's the tank that's leaking.
change the tank but then keep a sharp eye on the coolant level (daily at first) until you're satisfied that the intercooler is not involved.

regarding expansion tanks in general:
they are an infamous weak point in BMW cooling systems, have been for decades.
over the years I've changed out nine expansion tanks on various cars of mine. you'll be interested to learn that every one of those failed tanks passed a pressure test.
imo BMW radiators and expansion tanks are routine maintenance items with a credible lifespan of 65-70K miles, depending on conditions.

[damageprone]

Originally Posted by ///FastEuro

Out of warranty @ 53K miles.

Got you. Some members have asked for a good will repair as you’re not that far off. But otherwise you already have a replacement.

[///BMW Junkie]

Originally Posted by damageprone

Got you. Some members have asked for a good will repair as you're not that far off. But otherwise you already have a replacement.

I do but if my cooler is not leaking, I'm thinking to return the CSF and use the money towards the crank hub upgrade. Nevertheless, I want to be sure.

CSF cooler is a great part, personally since I don't track or drive the car too hard - I would rather keep my OEM contingent it's not leaking.

[Beemerm3]

So u should change the tank n from there see if u leak. At least the tank is a cheap fix.

[1hotrod]

I had the same problem, with the expansion tank leaking, which caused problems starting and holding idle. I am assuming the spark plugs were being drowned out, and bmw warrantie it.

About 15k when it happened,

[Unixed]

Originally Posted by Poiseuille

the white powder is from evaporated coolant, so it's the tank that's leaking.
change the tank but then keep a sharp eye on the coolant level (daily at first) until you're satisfied that the intercooler is not involved.

regarding expansion tanks in general:
they are an infamous weak point in BMW cooling systems, have been for decades.
over the years I've changed out nine expansion tanks on various cars of mine. you'll be interested to learn that every one of those failed tanks passed a pressure test.
imo BMW radiators and expansion tanks are routine maintenance items with a credible lifespan of 65-70K miles, depending on conditions.

Originally Posted by Poiseuille

Regarding expansion tanks in general:
they are an infamous weak point in BMW cooling systems

My expansion tank needs to be replaced. Dealer is quoting $809.28 to replace it. Seems crazy. Anyone know a reasonable cost?

[Poiseuille]

Originally Posted by Unixed

My expansion tank needs to be replaced. Dealer is quoting $809.28 to replace it. Seems crazy. Anyone know a reasonable cost?

main tank or IC tank? btw, how many miles on your car?

[Beemerm3]

I watched a video where the guy swapped csf coolers. It's mostly clips. And swapping smaller pieces. It shouldn't take too long.

[wdskukm3]

Looks like the expansion tank is leaking which is common. Change both the charge cooler and the expansion tank the same time that way you only need to fill the coolant once. Good luck

[BzsBimmer]

Originally Posted by Unixed

My expansion tank needs to be replaced. Dealer is quoting $809.28 to replace it. Seems crazy. Anyone know a reasonable cost?

Bmwpartpros has PN 17132284600 for $126 not incl tax and shipping. Doubtful if you need the brackets, bolts, and cap as those should just be carry overs.

Looks simple enough. Need to drain coolant from main radiator and fill with 50/50 and follow the DIY on bleeding (it’s self bleeding).

Hopefully that’s “reasonable” enough for you. You could buy a tool set, ramps, parts, coolant, and still have enough money left over for beer and blow.

[Pat M4]

You might have an internal intercooler leak like I had that needs to be fixed or it will cause misfires, hesistation, and can damage your intake getting coolant in the combustion chambers