Review on 🔧 Optimized Expansion Tank Cap by URO Parts - 17137516004 by Paul Varnado

I wanted to post this to help someone in my position. I drive a 5 with M54 engine. As with all M54 cars, the cooling system needs an overhaul from time to time. With a circulation of 250,000, everything will be replaced. After replacing all of the cooling elements, I noticed that I was running out of coolant, which was not the case before. I checked every hose, nut, bolt and connection. No luck. The most important thing to check for coolant leaks is a white coating. It's dried coolant. I couldn't find anything. Of course, when you go online and research something, you always find the worst. Every forum lists the cylinder head gasket. It was really hard for me to believe it was like that. Before the overhaul of the cooling system there were no problems, the engine did not overheat. Since I thought it might be, I just swapped everything out. I waited for the engine to warm up and noticed coolant dripping under the expansion tank. I was also able to remove the cap while the machine was running and the pressure wouldn't release. This cured my head gasket and determined that the system was not pressurized properly. Before going down this route, I replaced the new cap with an OEM cap. What do you know, the problem is solved. Now the system holds pressure and no leaks. The price difference is minimal. The best way to check that the system is holding pressure is to pinch the upper radiator hose. At temperature this hose should be tight. After about 3 hours of cooling, it should feel softer again. I have used uroparts in the past with great success. They offer great customer service and affordable prices to keep our old BMWs going. However, I would choose OEM for this part due to the minimal price difference. I hope this helps someone else before the head gasket is rebuilt.