We had a 2017 BMW 330i customer come in with a coolant leak. The car was regularly losing coolant so it was brought to our shop for diagnosis. We had to figure out why it was consistently losing coolant.
For this type of diagnostics, we like to use a coolant pressure testing kit. The tool allows us to pump in air into the engine’s coolant system. Once the engine’s coolant system is pressurized the coolant will be forced to leak out from the seals that have failed. Then we will be able to visually inspect the different components in the engine and see where the coolant is indeed leaking from. And that’ll help us narrow down the location.
Once we set up the tool and we pressurized the system, we were able to find the source of the leak. The leak was back here buried in the back of the engine.
Here you can see carefully if you look carefully, you can see the bubbling from the coolant seeping out slowly. So we found the source of the coolant leak. Now, mind you, BMW engines are very compact and the engine bays are super cramped. So it does take a bit of disassembly to get over in there.
Here we found the culprit. This part that is leaking is oil filter housing. Here you can see that one of the coolant passages in the oil filter housing has failed. You can see the plastic is cracked, allowing the coolant to seep through and causing you to lose coolant. Now, this is one of the common problems with BMWs. The oil filter housing is made out of plastic. And on top of cooling the engine oil, it also has passages for the coolant to go through. And with it being made out of plastic, the heat cycles from the engine getting hot, getting cold, eventually make the plastic brittle and cause it to crack, causing problems.
This is an inherent problem with all BMW designs and they continue to make their oil filter housing out of plastic. So, the solution to fixing this coolant leak will be to replace the oil filter housing. We will replace the housing with a brand new housing, brand new seals and of course everything will be torqued to spec. Once all that is replaced and installed properly, this engine will be good for a long while.
If you have a European, Asian or domestic vehicle in need of maintenance, diagnostics, auto repair or collision auto bodywork, feel free to contact us at Tolima’s Auto Center , your one stop car repair shop in Long Island City, Queens.
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