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  • Writer's pictureTeam Vebo

Are you a gambler?

BMW, the ultimate driving machine is well known for its handling and performance. One very important aspect to take note of is the cooling system. Because the cooling system consist of multiple hoses secured by plastic clips, there is a need to check the hoses regularly and change it when it is in a bad shape or when your car reaches a certain mileage.

Maybe you’re wondering by now, what does this got to do with my BMW? It’s quite simple actually, would you gamble not changing the upper and lower radiator hoses that costs RM400 a pair and risk blowing an engine due to hose breakage. I’ve sure our readers are aware that blown engine = costly repair. Are you willing to be a gambler and take that risk?

Most BMW engine coolant system is supported by rubber hose, but why does it break? Here are the details of it.

Yes, most of the hose are made of rubber like Japanese car but BMW coolant hose are equipped with plastic connector at each end. Why plastic connector? This is because most of it are quick connector that is secured with clips or just secured with stainless steel hose clip.

Here are some sample pictures of the plastic connectors:

The hoses starts to deteriorate over the time as they are subjected to heat over 100 degrees Celsius and pressure between 30kPa to 200kPa when the engine is running. Over a long period of time, we notice that the hose started to leak and this is an early sign before the car breaks down due to overheating.

Old Vs New, brown color is the sign of plastic deteriorating.

When the seal started to give way, the coolant leaks out and crystalized when oxidised.

What happens when you do not pay attention to this?

You’ll be driving your BMW, suddenly, your iDrive will tell you that your coolant is insufficient(read our blog post “Coolant-level-low-message-and-how-to-avoid-costly-repairs” to learn how to deal with this). Within minutes, your engine will start to overheat and you’ll need to stop your car and wait for the tow truck.

Here’s an example where the hose parted. You’ll also note that the hose is swelling.

This is a close up image on how does the broken hose looks like. You can see the solid plastic had deteriorated and had now become brittle after a long period of high temperature and pressure exposure.

As you can see the job of removing the broken hose is still not yet complete, the broken remaining socket still stuck inside.

This is the comparison between broken hose and the new hose.

Broken Socket

Deteriorating plastic, high pressure and heat causes the parting. In this particular car, the high pressure was caused by a jammed thermostat

New Vs Old Thermostat Housing

New Vs Old Thermostat and Water Hose

As a conclusion, we recommend that the water hoses to be replaced when you begin to experience a leak or flaw in one of the hoses. If your BMW is over 4 years old or has more than 100,000 km, then it is a good time to have a trusted mechanic check the hoses and see if it needs replacing. If you primarily have highway miles, that is good estimated time frame, but if you frequently drive in stop and go traffic or in a city, then you may want to have the hoses looked at earlier.

So, are you a gambler?

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