* E46 Cooling Guide (Information w/parts list/bleeding) *

I'm losing roughly 30 ounces of radiator fluid a week. This has been going on a few months. I've just been adding fluid weekly.

I really don't want to cough up @ $800 though... at least I replaced the water pump last year, so I don't have to buy everything...

If I'm losing that much fluid does that narrow down the guesses as to where the leak is at? I assumed it was the expansion tank.. but I dunno now.

A quart a week is lots.
Probably the expansion tank or radiator, or hose connections.
But at that rate you should be able to see where the leak is coming from with a decent inspection.
Get under the car and remove the bottom shield.

Are you topping off with anti-freeze or just water? (distilled)

Originally Posted by Stinger9

A quart a week is lots.
Probably the expansion tank or radiator, or hose connections.
But at that rate you should be able to see where the leak is coming from with a decent inspection.
Get under the car and remove the bottom shield.

Are you topping off with anti-freeze or just water? (distilled)

Yeah I need to get under there and check it out. I've been lazy with it. I have some time tomorrow where I can the exp tank and hose connections.

I have been using radiator fluid and hose water

Let us know what you find

Yeah I will.

When I was in "extreme PM mode" last summer I didn't care about dropping $800 bucks for a new cooling system. But now I don't know if I really should do it. Money isn't exactly tight, it just seems unrealistic. Uggh. haha

Originally Posted by sweetbro858

Yeah I will.

When I was in "extreme PM mode" last summer I didn't care about dropping $800 bucks for a new cooling system. But now I don't know if I really should do it. Money isn't exactly tight, it just seems unrealistic. Uggh. haha

So you didn't replace it all? Seals in the hoses and everything else break down over time. There goes your water.

Originally Posted by E46Mango

So you didn't replace it all? Seals in the hoses and everything else break down over time. There goes your water.

Nope. Will prob order everything through BMA

When I'm running the AC on a hot day and the fans are running really loud, is that also a sign of a withering cooling system? Or is it just because the outside temperature is over 90 degrees

Originally Posted by sweetbro858

Nope. Will prob order everything through BMA

When I'm running the AC on a hot day and the fans are running really loud, is that also a sign of a withering cooling system? Or is it just because the outside temperature is over 90 degrees

The fans will only come on when they need to. If you're idling on a hot day, they might need to. If you have air in the system and your car needs help cooling, they also might need to. Hard to say but I wouldn't worry about it.

Yeah for sure, I've always worried about it. It sounds as if I'm driving a huge SUV, not a little coupe.

Well my fans only come on at high speed (to the point where the sound can be noticed) when i've driven a canyon road up hill. basically 5 minutes straight of constant acceleration.

Originally Posted by sweetbro858

Yeah for sure, I've always worried about it. It sounds as if I'm driving a huge SUV, not a little coupe.

Maybe you have a loud fan. Check the fan for broken blades, or bad bearing.

So, I'm new to the forum and have been reading much of this thread. I'm a computer/web guy. I have built computers for fun, but when it comes to mechanical under-the-hood stuff, I can change the oil and filters, but admittedly that's where it stops for me with comfort level. This all sounds great and I get interested, but it also scares the hell out of me. Seems like I'd be nuts to even try this sort of thing on my own, not knowing where or how to begin.

Am I stuck just finding a local mechanic and paying the labor or am I nuts? Thanks.

You know yourself best. All of us started out knowing nothing. Some worked with others who taught them.
I just started reading and working on things. The cars teach you themselves if you have already read up on the project. Don't start with big jobs because nothing ever goes normal. Situations always come up where you'd better know a few tricks. We're all always learning more of them.
Best would be for you to have a friend who's ahead of you on the learning curve.

Ok, so this may be a little rant but I'm absolutely fed the hell up with bmws. I've had nothing but problems with the 4 I've owned. But for some reason I can not stop buying another! Am I crazy or just an enthusiast. Rhetorical question. Anyways back to the subject at hand. I own a 05' 330i Zhp. Two weeks ago I got a flat tire and a hose on my radiator bursted at the same time. All the coolant leaked out. Luckily my insurance covered this whole ordeal. When the shop diagnosed the problem they said I need an overhaul on the cooling system. I pretty much knew that was coming because I had to continually refill my coolant these last few months. So they replaced the radiator, misc. hoses, lft and rt radiator mounts, serp belt, fan blade, shroud, so basically a complete over haul of the cooling system. I just got my car back this Saturday and I was driving it down to San Diego from NorCal and I accelerated to pass a car on the freeway and then my coolant level light abruptly turns on then I look in my side view mirror and I see a massive trail of some liquid I believe is coolant and I was right. I has to get my car towed from LA to SD. Horrible, right? When i got to my house with the car I tried to see where the leak was and i poured water into the res. tank and the water leaks out real quick out of a hose that's directly connected to the radiator. I believe it's the water return hose. Not sure. The water is leaking from a hose directly under the expansion tank. I pour the water into the tank and it takes about a couple seconds to leak out of the fitting. And it's not leaking out of the expansion tank. It's leaking out of the radiator hose fitting. I drove the car for about 350 miles before it went out. And it happened when I gave it a hard acceleration. What could of caused this to happen? And from my description where does the leak sound like its coming from. I want to be some what knowledgable when I take my car in for repairs. I seriously can't stand auto repair shops. THEY ALL LIE! And thanks in advance for any feedback!*

Very hard to find a good shop that charges fairly and does good work. That's why most of us here do our own work.
Sounds like you got shoddy workmanship with improper connection of the hoses. You must take care to put them on properly. There is skill in every task.
Aside from your problem, sounds like you didn't do a new pump and thermostat?

Have you read the entire sticky on cooling system overhaul.
Did it on my car and never had one cooling problem in 96K miles.

Was the ET replaced too. You did not say.
This is the first place we all check for leaks.

Originally Posted by Sforza209

Ok, so this may be a little rant but I'm absolutely fed the hell up with bmws. I've had nothing but problems with the 4 I've owned. But for some reason I can not stop buying another! Am I crazy or just an enthusiast. Rhetorical question. Anyways back to the subject at hand. I own a 05' 330i Zhp. Two weeks ago I got a flat tire and a hose on my radiator bursted at the same time. All the coolant leaked out. Luckily my insurance covered this whole ordeal. When the shop diagnosed the problem they said I need an overhaul on the cooling system. I pretty much knew that was coming because I had to continually refill my coolant these last few months. So they replaced the radiator, misc. hoses, lft and rt radiator mounts, serp belt, fan blade, shroud, so basically a complete over haul of the cooling system. I just got my car back this Saturday and I was driving it down to San Diego from NorCal and I accelerated to pass a car on the freeway and then my coolant level light abruptly turns on then I look in my side view mirror and I see a massive trail of some liquid I believe is coolant and I was right. I has to get my car towed from LA to SD. Horrible, right? When i got to my house with the car I tried to see where the leak was and i poured water into the res. tank and the water leaks out real quick out of a hose that's directly connected to the radiator. I believe it's the water return hose. Not sure. The water is leaking from a hose directly under the expansion tank. I pour the water into the tank and it takes about a couple seconds to leak out of the fitting. And it's not leaking out of the expansion tank. It's leaking out of the radiator hose fitting. I drove the car for about 350 miles before it went out. And it happened when I gave it a hard acceleration. What could of caused this to happen? And from my description where does the leak sound like its coming from. I want to be some what knowledgable when I take my car in for repairs. I seriously can't stand auto repair shops. THEY ALL LIE! And thanks in advance for any feedback!*

The answer is in your own words. You *basically* did a complete cooling system. But did you do it all?

Here's the easy answer.

Did you replace everything on my list? If not, that's why.

Reading your posts for the first time, Mango. Great stuff, great information. Thanks! I've had my '02 330 CiC for a little over ten years now and have decided it's time to do a little maintenance, meanwhile things are getting old and breaking and I don't want (also can't afford) a new one. Picked mine up in Munich and still have the German plate in the front.

Anyway, I just have a few questions for you. Sorry if they sound kind of amateurish but hey, I'm an amateur! Plan on doing as much of the maintenance myself, as possible, and want to get it right. The first time.

*Do you always recommend changing the radiator? Mine shows no signs of staining or weeping. In fact, with just a little effort over the years, my engine compartment looks almost brand new. Amazing.

*What part did you get from Amazon and why?

*Assuming bleeding the system comes at the end, after installing all these parts, do you then refill the radiator, then put the car up on ramps, then bleed? If so, is it okay to run the engine long enough to get it up on ramps? And then should it be cold again before bleeding?

Thanks for all the information you provide on this site,

Steve

Radiator is cheap, so not much reason to avoid replacing it unless you gamble that they don't build them now like they used to!
And little reason to panic here, because the rad leaks come on slow rather than the major coolant dump that an ET or burst hose will cause, and thus endanger your engine.
A weeping radiator can always be swapped out later if you don't mind taking things all apart again after draining your coolant.
I say personal call.

Hey guys I'm new to this so if I do anything I should not than please tell me!! Anyway I have an e46 318ci coupe (year 2000) and the coolant was leaking out of the hose connector on the side of the block. I replaced this with a new part from my BMW dealer and the leak stopped on the block, but I'm still loosing the coolant, I can't see any leaks visually but it's going somewhere , the car is not overheating and is blowing hot air so I don't think it's the head, I'd love some help, it's a 1.9 petrol in case anyone asks, thanks

Originally Posted by sgoetz628

Reading your posts for the first time, Mango. Great stuff, great information. Thanks! I've had my '02 330 CiC for a little over ten years now and have decided it's time to do a little maintenance, meanwhile things are getting old and breaking and I don't want (also can't afford) a new one. Picked mine up in Munich and still have the German plate in the front.

Anyway, I just have a few questions for you. Sorry if they sound kind of amateurish but hey, I'm an amateur! Plan on doing as much of the maintenance myself, as possible, and want to get it right. The first time.

*Do you always recommend changing the radiator? Mine shows no signs of staining or weeping. In fact, with just a little effort over the years, my engine compartment looks almost brand new. Amazing.

*What part did you get from Amazon and why?

*Assuming bleeding the system comes at the end, after installing all these parts, do you then refill the radiator, then put the car up on ramps, then bleed? If so, is it okay to run the engine long enough to get it up on ramps? And then should it be cold again before bleeding?

Thanks for all the information you provide on this site,

Steve

My car had 157k miles on the clock and gave no "signs" of needed a new radiator. The temp gauge always stayed in the middle. I found the hidden OBC menu that shows the actual temp (in F) and discovered I was running higher than should be, but not enough to overheat. So I replaced as a PM as Mango and suggest. I could not believe what a difference it made running back at "normal" temp made. You can tell the engine is working better, more power than before especially at freeway speeds. You didn't say how many miles but I would replace along with the other parts recommended in this guide.
p.s. my radiator was not leaking but was caked in dirt. I can only image the internals.