Radiator exploded, should I replace anything else?

[bluptgm3]

Pull the cap off the AC tensioner pulley. The idler/tensioner pulley fastener is used to de-tension the belt, similar to the Alternator/Water Pump belt tensioner. Applying tightening force to the fastener 'collapses' the tensioner, loosening the belt.

Are you outside the USA?
I've seen replacement end tanks online, but no one that I'm aware of replaces them here in USA.

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[Vintage42]

That's what the radiator shop did. They said it was not an age-related failure, but excessive pressure....

High pressure caused by overheating caused by thermostat failure caused the aged brittle plastic tank to split. Many do:
https://www.bimmerforums.com/forum/s...1#post29764581
A new tank would have held the pressure.

[rf900rkw]

Exactly. The coolant cap is set to 2 bar. This is not the operating pressure. This is the safety valve in case things go wrong, such as an overheat. It dumps before anything else can break. If the radiator split first, it is at fault. It could not stand to designed max pressure.

[JKuhn]

bluptgm3: Thanks for the info. And yes, I'm outside the USA. South Africa, to be exact.

Vintage42: I'll read through the thread a bit later, it's getting late here.

rf900rkw: Noted.

[Dakar Ole]

Have any pics of the broken thermostat? Seems weird.

[JKuhn]

Unfortunately not. The club member whacked it against a tree in an attempt to get the old hose off (the hose was stuck, and the shop didn't have those hoses).

But basically the washer at the end came off (it ended up in the radiator), and that larger ring (which holds the outer spring) stuck to the engine block.

[Vintage42]

... Vintage42: I'll read through the thread a bit later, it's getting late here...

Not a thread, just a post with a picture of another tank like yours.

[JKuhn]

Update:

I ordered a new lower radiator hose, but now I've heard it's on back order. So I patch fixed the old one (the o-ring was stretched and forced in, so the coupler cracked when we took it off the old thermostat). I'll fill the system tomorrow morning and see if it holds up. If so, I'll only drive short distances for the time being, and perform paranoid check-ups. If not, I'll buy an E46 hose and modify it to fit (it's getting very pricey though, so I'd prefer not to do that).

One question though, just to be sure. I removed the clutch fan to get to everything, and didn't put the blades back (the clutch itself is still there). Will the aux. fan be enough? And at what coolant temp should it come on (for testing, by using the car's diagnostic mode)? For what it's worth, temperatures here can go into the low 30's (Celcius) this time of the year, but currently the forecast for the next 12 days only show 25 and lower.

[Vintage42]

... I removed the clutch fan... Will the aux. fan be enough? And at what coolant temp should it come on... temperatures here can go into the low 30's (Celcius)...

That's 86F.
Clutch fan delete is a popular mod for the 6-cyl, so it must work.
My 4-cyl did not come with a clutch fan, and the electric fan works fine. It only comes on when idling in hot summer traffic. According the digital ScanGauge on my console, my normal running temperature is 206F and the electric fan comes on at 212F. It knocks the temp to around 200F in a 5 seconds, and the cycle starts again, until the car gets moving. The electric fan is not needed as long as the car is moving, even slowly.

[rf900rkw]

I am one of the biggest proponents of mechanical fan delete, and I will say that in your case it is NOT a good idea. Contrary to popular myth, the fan is not controlled by engine temp at all. It is controlled by radiator temp. The fan doesn't cool the engine, it cools the radiator. Thus, if there is a problem with the cooling system that limits flow through the radiator, the electric fan will not come on as the engine overheats because there is nothing for it to do; the radiator is cold. In the case of your crippled and bodged cooling system, I fear future overheats are inevitable and having the fan removed will only give you another false culprit.

[JKuhn]

Makes sense.

[JKuhn]

It's alive!!!!

I had to replace that hose, so I ended up buying an over-the-counter 320i/323i hose, and removed the radiator coupling. It's a bit on the long side, so I had to fold it slightly, but it lets enough water through, without spilling it all on the road.

[Vintage42]

I am one of the biggest proponents of mechanical fan delete, and I will say that in your case it is NOT a good idea...

Why can everybody else do it and not him? What would he need to do to just use the electric fan to cool the coolant?

[Wertles]

Why can everybody else do it and not him? What would he need to do to just use the electric fan to cool the coolant?

simple. The deleted fan works with a well functioning, up to par cooling system. This cooling system is in need of replacement, has patched together hoses and is being limped along at the present moment. There are many points of potential failure and having the fan on will help the system hold together at this time. On a well functioning cooling system, the fan is fairly useless and is the weakest point of the system. In this case, the rest of the cooling system is the weak point and can use any help it can get. Once everything else has been replaced, take the fan and throw it in the garbage.

[rf900rkw]

The OP may not be at the end of the road on cooling diagnosis. Now is not the time to add a fan delete to the variable table. When something goes wrong with a cooling system, coolant quits flowing through the radiator. Stuck thermostat, blown head gasket, big leak, doesn't matter, the end result is no coolant flow. With an electric fan, the fan will not come on since there is no heat in the radiator. With a mechanical fan, the fan will still be turning, lufting along pulling cold air over a cold radiator. With the mechanical fan in place, the diagnosis will go to "why did it overheat?". With just the electric fan, the common first step is "it overheated because the fan didn't come on" when the truth is the fan didn't come on because it was overheating.

[JKuhn]

Just to let you all know, everything seems fine so far. I also re-installed the clutch fan (without the shroud though, I was too lazy to take the radiator out again).

And regarding the hose I'm using, I simply removed the radiator side coupler (first cut it as close to the hose as possible, then carefully cut and collapse the part inside the hose), and put the hose on. Like I said, it's not a perfect fit as the part between the two bends is a bit on the long side, but it works (and it'll work for however long it takes to get the proper hose).

[bluptgm3]

The engine driven fan can be ineffective without the shroud, fan requires the shroud to direct/channel air flow.


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[JKuhn]

Won't it just be less effective without the shroud? I'd rather not take the radiator out again until I have the hose I ordered.

[MIKYZZ4]

You should be fine until the hose is available,
Just keep an eye on coolant temp gauge for temp abnormalities.

[JKuhn]

Will do.

I'll see how the car behaves the next few days (I do have the Mazda as a backup), but it seems there's a show in about a week, and it's a 400km round trip.

Also, I know the system can now stand up to the rated 2 bar, because the system was overfilled (I wasn't sure about how full it should be so I asked an independant BMW which I don't really trust to work on my cars), and it dumped most of the excess water without issues. I'll just take the rest out manually.

[Mr Bingley]

You probably shouldn't drive it until you have the correct parts and have it all put together properly. Like I said, you got lucky once...

[JKuhn]

I doubt the hose I'm using now will come off. I'd just prefer to have the right on on there, which will also flow a bit more freely. Plus I'm the type who's bothered by it not being the right hose.

Since it's mostly open road I doubt the shroud will be a problem, and I already know that it can handle smaller streets and some traffic.

EDIT: Before I went on the first post-repair test drive, I let it idle quite a while (without the engine fan though), and I couldn't even get it to the thermostat opening temp (just barely not). I ended up driving the car to get the thermostat to open (so I could test it).

[Sleepyhead97]

after you drive the car, and let it sit to cool down. Once Cool, do your hoses still have pressure in them? If so, its a headgasket problem.

[Mr Bingley]

I doubt the hose I'm using now will come off. I'd just prefer to have the right on on there, which will also flow a bit more freely. Plus I'm the type who's bothered by it not being the right hose.

No, you're the type to use the wrong hose which restricts flow, and drive it anyways, without a shroud, on a long trip, out of town. Not judging, just being clear about types.

[JKuhn]

after you drive the car, and let it sit to cool down. Once Cool, do your hoses still have pressure in them? If so, its a headgasket problem.

Nah, there's no abnormal pressure buildup. That was actually the second thing I checked (after leaks), and I checked it after every drive for a while (both with the car running and off).

Mr Bingley: I suppose you could see it that way. But as I said, the hose works well as it is. This one just needed to be bent a bit further to fit (not enough to cause a noteworthy restriction though). I won't drive it if I have doubts about whether the cooling system will work. Without the clutch fan it went up to 96 Celcius when pulling away (97 only once), around 94-95 when driving and as I said I couldn't even get the thermostat to open when I let it idle before the first drive. Those temps are according to the cluster diagnostic mode, and the thermostat is rated at 97.

And as I said, I'll drive the car more before I decide if I'll go with it (including a trip on the open road). And while this is also a Cars in the Park event (the only one I know is HUGE), this is a smaller one which according to the info I have cannot even compare to the one I'm used to. I'll definitely not drive it to a show where I'm expecting to get stuck in traffic (and if I do get stuck, I'll turn the diagnostic mode on and monitor the temp in real time).

I suppose I could put the shroud on, but I'd really rather not do it unless I have to. By my reasoning removing the radiator without a real need for it only increases the risk of something going wrong.