1998 BMW 740 Temperture

You may have a bad radiator cap, I wish you would be more specific, is the vehicle using coolant? And if so, have you bled the air out of the system? Get back to me and tell me a little bit more.

Also the cooling system has plastic in it and it has a lifespan of 5-7 years. Inspect and pressure test the cooling system. That means the pressure cap too.

You failed to answer my questions, but I did get a new hint from your message "Water is going somewhere but I don't know where" I'm assuming now that you have to add cooled to it, if you don't see an obvious leak in your driveway, the only other place to coolant may be going, is inside your car, pull up the floor mats, take your hand and feel if the carpet is wet, I am not talking about the heater core, if the heater core is leaking it will drain down behind the transmission, it has a right and a left drain for the heater core, what I'm talking about is the junction block that feeds the heater cores located directly behind the engine on the firewall, it is aluminum with three hoses, for some reason on the 1998 BMW, the O-rings fail, or the junction block rots away, from people using the wrong coolant, so check that out and get back to me.

If the valley pan is leaking, you will need that book. I like the Robert Bentley publications, they are easy to understand.

Yes! But the factory OEM manual is way better and more precise, to walk you through it step by step, its just more money.

There is no factory repair manual, it is all on CD or online mate. The Bentley manual derives its info from the factory data base and it is what is recommended.

Sorry that's what I meant Dr. Hagerty, ( I was trying to back you up) the Bentley manual is so good, you think you are looking at the factory manual, because it is so good, they cost me about a $100.00 apiece. They are very explicit and very detailed, I have read so many posts on this site, I think I'm starting to suffer from, being nonspecific and very general ( I will not let that happen again). I apologize.