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E46 '04 330Ci convertible 740K km
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It is important to have clear understanding of processes going on in coolant system. Nothing fails all of a sudden, there are certain things leading to faults. Not talking of issues caused by low quality parts. Soft failing thermostat, damaged fan clutch or radiator cells covered with dirt can significantly load cooling system by raising overall temperature = pressure in cooling system, and you can drive car with such issue for long time, not knowing that as temperature is within temperature gauge threshold, Then bursted ET or cracked radiator - and then complaints of stupid design, etc. Simple replacing damaged part without finding a cause will keep you running till next weakest element dies.
 

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Some knowledgeable people suggest 90k miles for rad preventative replacement. Others cite examples of them lasting much longer. Quite similar to the fuel pump life debate. As suggested above, there are a few variables that might affect rad life.
I believe in changing things at my convenience, not when the BMW gods decide its time. Much depends on your risk tolerance level and the consequences of having a sudden catastrophic failure on the highway. I drive my car to Florida every winter. I don't want to get stranded or left to the mercies of a dealer.. You may never go more than a short tow from home.

As I recall, to do the pump, I think its easier to pull the rad first. The hoses are undone anyway, the system is drained, so you're looking at the incremental cost of the rad. I understand budget constraints may apply, but in the US, that would be under 150 delivered. If your only parts source is the dealer however, then you may want to take a chance.

I'd be curious to know how a mechanic can determine they are in good condition. Just because they don't leak today doesn't mean they won't start acting up tomorrow. But YMMV.
 

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E39 E90 E46 F10
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^ Yes on having kept the radiator, yes on having replaced the expansion tank (the part was revised in 2007) but hit or miss on the water pump. I've had an OE, Graf, Duralast and Stewart pump in my car but only one of them made it past 50k.
 

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320i '04
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Discussion Starter #25
The main failure point of the radiator is leaking, either from a crack or at the plastic/aluminum joint.
Speaking of cracks, I just checked for visual wear on my current radiator. Noticed that at the lower end of the radiator it looks like it’s separated into two parts. Look at the red line I drew onto the picture. Kinda hard to se but it looks like one half of the radiator is further down than the other. Why the f is it separated??? Other than that it looks really beaten, up so I believe a replacement is due. But I won’t be replacing the mounting bracket since I already gone over my budget.
911179
 

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E46 '04 330Ci convertible 740K km
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It is not clear what pic shows, but if you decide to replace radiator, squeeze some more of your budget and replace mounting plate too. It is made of plastic, and it gets lot of load from coolant as well as from holding ATF heat exchanger and expansion tank, and as you know you probably not gonna replace it preventatively later, as it is same job as radiator replacement, so not doing it now pretty much means you gonna wait till it fails.
 

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320i '04
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Discussion Starter #29
That looks odd, but google e46 rad and look at the pictures.
Just took the radiator out of the car and well, the whole thing has started to sag. Just ordered a Nissens radiator along with at new mounting plate, since I now clearly can see it needs to be replaced.
911206
 

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320i '04
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Discussion Starter #31
Just in time I'd say. Is that The one your mechanic said was in good condition?
I’ve rarely let a mechanic look at my car since I do most work by myself. So it was my mistake to think it was in “good” condition.

But that the radiator was in such bad shape the car seller probably should have said :rolleyes:
 

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^ Yes on having kept the radiator, yes on having replaced the expansion tank (the part was revised in 2007) but hit or miss on the water pump.
Fair point. I now have the funds and will replace those parts* when the car goes in for its MOT and Inspection II in January.

* Water pump/radiator/any connecting hoses.
 

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'04 330ci 6MT
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Fair point. I now have the funds and will replace those parts* when the car goes in for its MOT and Inspection II in January.

* Water pump/radiator/any connecting hoses.
For the UK, i'd do the rad if it's bowed like in AntonSuu's pic. I'd do thermostat, pump, upper hose, lower hose, expansion tank and expansion tank cap at the same time if they're original or have been in for 100,000 miles or ten years. If a single item had failed prematurely and the rest of the system was fairly new still I'd just do that one item. That's just me though, and based on reading forums not being a mechanic.
 

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On my 330i my original radiator lasted 169K Miles until it developed a small leak in the area where the plastic tank is joined to the radiator. The rest of the components had failed at different times and I just replaced them when needed. I would take Mr. M Car's advise though. He works on BMWs for a living and has an Excellent reputation for his vast knowledge and with helping out others.
 

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2001 325ci
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FWIW, replaced my original radiator at 270500 miles (2016), just because damaged due to running over frozen turkeys on the freeway
 

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144k miles on my original radiator from 2001. Not going to bother changing it until it leaks or breaks.
 

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I did not replace my radiator when I did my tranny rebuild and replaced the expansion tank and hoses and regret not replacing the radiator. It is leaking due to a crack I more than likely caused. Just bought a Nissens and will be replacing the soft seals as well. I’d highly recommend replacing it.
 

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E39 E90 E46 F10
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Good to replace that. But that’s not sagging per se. That‘s moisture that gets trapped in the dirt between the fins and crystallizes (which expands in volume, pushing the fins down) at night.
 
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