[k!dGhøstX_X]

E90 N55 owner here. I'm new to e90Post so my replies may take some time. My coolant level has been dipping a week or 2 after filling it up. I removed the undercarriage cover and pressure tested the expansion tank to check for leaks. Found coolant gushing out of the area marked on the attached image. This is on the driver side of the radiator/intercooler system. I removed the intercooler to check what the issue was and found no faults, no broken seals, no cracked plastic, nothing visible. Went ahead and re-installed it, but now it's bugging me. What could've caused the leak? Is the intercooler just old (it is the OEM one from 2011) and can that cause backups of coolant/leaks, or is it another issue? :/

[StradaRedlands]

Could it simply be the radiator core is giving it up and separating from the plastic?

[Andystobbs]

Book into a garage.

[k!dGhøstX_X]

So the red circles in the picture are where the coolant was gushing out at around 15psi pressure testing. The metal is the intercooler's corner.
I dont see leaking coming from anywhere else, no signs of dried residue, nothing.
Would that still be a radiator plastic issue?

[lowrydr310]

There's no coolant in the intercooler.

It's probably leaky radiator end cap seams, exactly how my two year old replacement Behr radiator failed. I replaced with another Behr, 4 years later it's not leaking.

[StradaRedlands]

Originally Posted by k!dGhøstX_X

So the red circles in the picture are where the coolant was gushing out at around 15psi pressure testing. The metal is the intercooler's corner.
I dont see leaking coming from anywhere else, no signs of dried residue, nothing.
Would that still be a radiator plastic issue?

The radiator is aluminum sandwiched in plastic, and the plastic gives up after so many heat cycles. It could be an O-ring on one of the hoses, but I think the radiator itself is a good guess.

And yes, intercooler is just compressed air that is being cooled, no fluid involved.

[k!dGhøstX_X]

Originally Posted by StradaRedlands

The radiator is aluminum sandwiched in plastic, and the plastic gives up after so many heat cycles. It could be an O-ring on one of the hoses, but I think the radiator itself is a good guess.

And yes, intercooler is just compressed air that is being cooled, no fluid involved.

Ohh ok ok. I'll have to check the radiator then. Probably will replace within the next month. Thank you!

As a follow-up question, how do you know if your intercooler is air-to-air or air-to-water?

[k!dGhøstX_X]

Originally Posted by lowrydr310

There's no coolant in the intercooler.

It's probably leaky radiator end cap seams, exactly how my two year old replacement Behr radiator failed. I replaced with another Behr, 4 years later it's not leaking.

Will look into Behr. I'm thinking about replacing it within the next month. Much appreciated

[Andystobbs]

Originally Posted by k!dGhøstX_X

Ohh ok ok. I'll have to check the radiator then. Probably will replace within the next month. Thank you!

As a follow-up question, how do you know if your intercooler is air-to-air or air-to-water?

If it's air to air it sits right at the front of the car in the air stream, is generally massive, looks like the kind of contraption thats optimised to dissapate heat to the surrounding atmosphere by virtue of a billion fins designed to increase surface area and has no pipes other than the air pipes.

You're in over your head.

[TheMidnightNarwhal]

Originally Posted by Andystobbs

Book into a garage.

That's not what we do around here

[Andystobbs]

Sometimes I get cars in my garage that would have been far better off if enthusiastic but reckless owners just left them well alone.

I'm all for having a go at stuff but I probably won't be offering to help with an appendectomy without knowing a thing about it.

[TheMidnightNarwhal]

Originally Posted by Andystobbs

Sometimes I get cars in my garage that would have been far better off if enthusiastic but feckless owners just left them well alone.

I'm all for having a go at stuff but I probably won't be offering to help with an appendectomy without knowing a thing about it.

Yeah I think you are freaking a bit much. I used to be like this person when I started learning and look where I am now. You all start somewhere and ask questions and you learn as you go. Mechanic work is not rocket science. Sure some people will cheap repair it out but that doesn't mean anyone who DIYs does that.

[StradaRedlands]

Originally Posted by k!dGhøstX_X

Will look into Behr. I'm thinking about replacing it within the next month. Much appreciated

Originally Posted by k!dGhøstX_X

Ohh ok ok. I'll have to check the radiator then. Probably will replace within the next month. Thank you!

As a follow-up question, how do you know if your intercooler is air-to-air or air-to-water?

All air, nothing wet. Most people upgrade with the VRSF chargepipe and intercooler at some point

Radiator replacement is a breeze on E90... go for it! FYI, Behr has some negative experiences posted here. Probably fine, but most everyone likes Nissens or if you want to put out a few more $$$, get the CSF all aluminum heirloom quality unit!

Do at least the upper and lower hose while you're there. As well as the Mickey Mouse flange, as well as the... well, it never ends.

[k!dGhøstX_X]

Originally Posted by TheMidnightNarwhal

That's not what we do around here

This is exactly right! Wouldn't be much of a passion if it doesn't make you sweat, think, and curse out loud a ton �� Thank you for being kind and informative. I know this is a lot to learn but i knew coming here for help would be the right guiding tool!

[k!dGhøstX_X]

Originally Posted by StradaRedlands

All air, nothing wet. Most people upgrade with the VRSF chargepipe and intercooler at some point

Radiator replacement is a breeze on E90... go for it! FYI, Behr has some negative experiences posted here. Probably fine, but most everyone likes Nissens or if you want to put out a few more $$$, get the CSF all aluminum heirloom quality unit!

Do at least the upper and lower hose while you're there. As well as the Mickey Mouse flange, as well as the... well, it never ends.

Oh boy some work ahead, should keep me busy this summer XD I cannot wait, these cars are just a beauty to drive (and care for)

Thanks for the recommendations and tips. I believe the charge pipe has been switched to an aluminum one, but the upper and lower hoses definitely need replacement. CSF...I've heard of that brand! Will check them out

[ldepason54]

Probably need new radiator. Stock ones can not hold pressure well after so much cycle. If you are going to go ahead and replace it. I suggest just going with full aluminum radiator that way you won’t have to worry about it again.

[TheMidnightNarwhal]

Originally Posted by k!dGhøstX_X

This is exactly right! Wouldn't be much of a passion if it doesn't make you sweat, think, and curse out loud a ton �� Thank you for being kind and informative. I know this is a lot to learn but i knew coming here for help would be the right guiding tool!

No worries. I feel you, I was faced with the same "If you need to ask you shouldn't do it" type of comments when I started 5 years ago. And now I can remove my camshafts and re-assemble my top end with no issues.

[lowrydr310]

Originally Posted by TheMidnightNarwhal

No worries. I feel you, I was faced with the same "If you need to ask you shouldn't do it" type of comments when I started 5 years ago. And now I can remove my camshafts and re-assemble my top end with no issues.

This is precisely why this community is awesome. Any time people ask me about buying an old BMW I say go for it, as long as you're willing to learn and get your hands dirty.

Owning an E90 is no different than owning any other old car. In fact it's better in some cases because all the repairs and maintenance steps are well documented, and in my experience E90 parts are often less expensive than parts for other makes/models. I'm talking OEM equivalent parts, like the same manufacturer that makes BMW parts with the logos not printed or just ground off, they're only slightly more expensive than the no-name junk from the auto parts store. I also own several Hondas and it's either Genuine Honda parts ($$$) or the no name auto parts store junk.