Nine problems related to radiator have been reported for the 1998 BMW 540. The most recently reported issues are listed below.
White steam was coming from under the hood onto the front windshield. The steam was fogging the windshield, and causing poor visibility while driving 50-55 mph. Consumer was able to get the vehicle to a repair shop. Dealer informed the consumer that the upper neck connector of the radiator hose broke.
Various problems involving 1998 BMW 540ia which was brought used. BMW had been importing vehicles for sale, fitted with a radiator that had plastic ends as well as supply and return under approximately 21 p. S. I. These radiators suddenly ruptured under load while driving, causing the drivers to swerve on impulse at impact of the rupture. The radiator was likely to rupture at about 80k miles.
I was driving down a busy street one evening and as I came to a light, smoke started coming out of my hood. Fortunately it was in the evening and traffic was lighter than usual. I pulled into a parking lot off the side of the road. Having known others that this has happened to, I first checked the radiator and sure enough, there was a large crack down the side of the housing. I had the car towed home and purchased a new radiator from BMW of seattle the following morning. The new radiator was about $200, a few hours of my own labor and a few more hours detailing the engine pay and headlights which had radiator fluid all over them. Also from the experience of others who own e39 BMW 540s, I fully expect this to happen again in the next 50k miles. I also expect the expansion tank to go within the next few months.
2nd catastrophic radiator failure. Not a leak, the neck breaks off causing immediate loss of cooling. 1st radiator at 45k, 2nd at 92k. Based on other's experiences, this is very common for this model (and even longer life than many). Causes loss of vision due to amount of steam released. Less experienced driver may have difficulty controlling vehicle to get to side of road quickly to shut down. No way to predict the failure. Same issue with expansion tank. Both failures are on plastic parts.
Multiple coolant defects on the 1998 540. The car has now had 3 radiators, 3 thermastats, water tube seals replaced twice, and a water pump. The costs have been over $3,500. These leaks are not just expensive, they pose a real danger to causing personal injury and damage. The failure rate is known to be very high. . Read more...
Plastic neck of radiator on my '98 BMW 540ia broke completely and suddenly on highway. White smoke came out under the hood. Saw temp gauge climb up rapidly. Pulled over immediately. Towed to dealership for repair. No one was hurt luckily.
Engine cooling radiator hose fitting broke off. Lost all coolant on highway. Dealer replaced radiator under warranty and stated it is common failure on 540i BMW due to plastic parts not stong enough to resist temperature. Well documented on private web sites.
Radiator failure.
Radiator neck sheared off without warning while my wife was driving on freeway. Caused immediate loss of coolant and emergency stop. Car had to be towed.