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I have '01 330xi and '01 530i. My 530i had a small coolant leak where I would find a small puddle of coolant on my garage floor. I too had a hard time finding the leak. I did a pressure test. Got to 15 psi and it would very slowly lose pressure. I determined that it was the thermostat because of small traces of coolant I thought I saw. I replaced the thermostat and water pump. Next day, same puddle. Turned out it was leaking from the plastic side of the radiator on the passenger side. I replaced the radiator and upper/lower hoses. My coolant pipes under the intake were changed about 20k miles ago and my expansion tank just 2 years or 2k miles (not my daily driver) ago so left those alone. I'm glad I replaced all those coolant system parts and the mechanic that did my reservoir used green fluid so i was glad to get that out of there too. At 240k miles and no history, there is no harm IMO of replacing the cooling system. If it fixes it, great. If not, hunt continues but at least you're good for another 60k miles on your coolant system.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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I had a leaky coolant level switch one time.
That would be a bad coolant expansion tank. The sensor has NO contact with coolant.

Matter of fact, the earliest E39's with the Low Cluster had no provision for a coolant level warning. Guess what, no sensor installed in the expansion tank either. No leaks...
 

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That would be a bad coolant expansion tank. The sensor has NO contact with coolant.

Matter of fact, the earliest E39's with the Low Cluster had no provision for a coolant level warning. Guess what, no sensor installed in the expansion tank either. No leaks...
Well, I did replace the expansion tank at the same time, and after reading up on it, you're undoubtedly correct.
 

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Discussion Starter · #25 ·
I took it to a shop and they said the heater inlet pipes are leaking. I plan on replacing those hoses and refresh the coolant system. It says on some of the posts to replace the manifold gasket as well. Do I need to this and the CCV system, too?
 

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I took it to a shop and they said the heater inlet pipes are leaking. I plan on replacing those hoses and refresh the coolant system. It says on some of the posts to replace the manifold gasket as well. Do I need to this and the CCV system, too?
Check the Links at tbe top of the page for article on intake removal and possible things to do. Yes to gasket, at your mileage and with no service record I d be doing most if you hope to keep the car.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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I took it to a shop and they said the heater inlet pipes are leaking. I plan on replacing those hoses and refresh the coolant system. It says on some of the posts to replace the manifold gasket as well. Do I need to this and the CCV system, too?
Unless the CCV system is less than a year old.... NOW is the perfect time to replace it!
 
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