1996 BMW 5 Series 528i Automatic from Spain - Comments

With 82000 km and excellent care, but without prior problem, the temperature needle went a little above the middle marking. When I reached my destination, about 8 km from home, the needle was at ¾. I turned off the motor and at that precise moment the needle jumped to the red level, steam started pouring out of the radiator and the radiator exploded, all at the same time.

I had to change the radiator, its deposit and cap, the thermostat, water pump and the motor (cylinder) head was damaged.

Official Dealer needed one month waiting time to take care of repair.

Knowing that I was attentive to the indications of the temperature needle and I did not drive the car at any time with the needle even slightly above the 3/4 mark (and the ¾ mark was reached only at the very end of two very short trips), I must ask the following questions:

1) How many things went wrong at the same time to cause such a massive problem?

2) Is it normal for a BMW to have so many things go wrong with it without any warning?

3) Why did it overheat so much so quickly?

4) Why did the temperature indicator needle only jump to red at the last minute?

5) If there was excessive pressure on the circuit, why didn’t the radiator cap fly off or a hose break?

6) Is there or is there not a safety measure in place on this BMW to stop the motor before massive damage can be done? If so, why didn’t it function?

7) Why and at what point was the cylinder head damaged? Why both the radiator and the head?

8) Why such a long wait for an appointment at the official BMW garages?

9) If the mediocre After Sale service at BMW forces me to go to other garages for repairs, what about any BMW warranty? Why should I pay in the future an overprice for the BMW garage? What is the added value for the client both in terms of the BMW brand car and its garages?

10) And, worst of all, since I don’t know how this chain of events happened, and even the BMW mechanic seemed baffled and the mechanic that worked on the car can’t explain it, how can I be sure it won’t happen again?

I believe that what happened to my car may well be attributed to a defect in manufacturing or in design. What is just not acceptable is that the indicators and safety measures that should have been in place on this luxury car did not perform and warn me of the impending damage.

I believe this case is more of lack of preventive maintenance then BMW's fault. Try flushing the radiator at least ONCE year. I doubt in your case you even realized how. Preventive maintenance helps.

Thanks for your suggestion. I am not an expert in car mechanics, but I have never heard that flushing a radiator is part of the car maintenance. I will be more attentive now. Anyhow, if this is important, why isn't it done regularly at the official BMW garage?

Hi. Yeah, a really unpleasant thing happened to your car. I own a 1992 BMW 520i.

Flushing a radiator once per 1-2 years is good preventive measure for problems like this. Radiators often get "blocked" dust, grass and other dirt and air doesn't circulate properly in such cases, so the engine might overheat.

I think your thermostat had problems and didn't monitor the temperature correctly, that's why the needle jumped to the red mark and the same moment as the radiator exploded.

Now, the cylinder block head of BMW engines is made of aluminum, it is very sensitive to overheating and that's why it got damaged.

It's not "normal/usual" for a BMW to have such problems, overall these cars are very reliable. I think the chain of this events happened in such a manner: the thermostat was broken (you might have not noticed that) => the radiator got blocked with dirt => the engine overheated.

By the way, was the water pump functioning normally? And what was the antifreeze level, was it normal? Maybe there was some hole in the radiator and some cooling liquid just leaked out?

I believe it's the BMW fault because I have a BMW myself and the same problem is happing to me right now. I'm thinking it twice of buying another BMW...

I would tend to agree that it was the thermostat, but I doubt your radiator blocked up with gunk, unless there was a LOT of red sludge coming out. Most thermostats only last 2-4 years and 40-60K Km. They may not be reliable for giving you a good temperature reading after that point.

Of more concern is to regularly replace your radiator cap regularly. they come with a spring inside which is rated to a particular pressure, and will release at the designed pressure when not old, worn out or with a leaky rubber gasket in them.

Its likely that the thermostat wasn't perfect, and the radiator cap overpressured the cylinder block, which then blew out the head.

If you've bought a secondhand car, and never changed your radiator fluid, check that its not clear. If it is, it's probably got a radiator leak. Also clear fluid includes no anti-corrosives, and this contributes to head gaskets and aluminium heads and blocks wearing out, so clear fluid = bad. Don't mix fluids either, replace the lot with the proper stuff.