HELP ??540i radiator leak, after expansion tank replacement?? HELP

[1995 540i]

Hey guys, so last month I had my 540i in the shop for regular oil change and what not. I had a radiator leak at the time and told they guy at the shop. He got back to me and said I would need a new expansion tank that mine was leaking and so I went ahead with the repair. I’ve had my car for a month now and it’s been so nice not having to top the car off with fluid before I drive somewhere. Well… I just left and went to the local store to pick something up. I shut the car off and I get the damn “coolant low” message. I turned the car off went in 2 get my stuff and get back in the car…no message on the way home? I opened the hood once I get back home (less then a mile from my home) and looked at the tank. The level of the fluid is low, pretty much at the bottom. Now im back to square 1 and I have a leak somewhere and don’t know where to begin to look for it. I did check my oil cap, no white residue. I done even know where to began to look since I though I had the problem fixed with a new expansion tank. The leak before was so bad I would have to fill it before I would travel anywhere. But now the leak seems smaller since I had replaced my expansion tank. Any ideas would be appreciated. Thanks…

[1995 540i]

Anyone???

[632 Regal]

Check where the main 2 radiator hoses go to the radiator. These radiators have plastic connections that crack and break usually where the hose clamps go. I didn't want to believe it myself but if you tighten the clamp it makes things worse. Mine I couldn't see any leaks, it evaporated before it dripped (dumped) water but when I was driving it was dumping. Also check along the sides where the tubes squeeze into the plastic tanks, saw that too. A new radiator isn't very expensive so if your oil cap isn't giving the tell tale signs on head gasket (pretty rare in a V8) then I would look to the radiator.

The hoses and belts are a maintenance item, all of them and this is the reason. Also check by the firewall where the hoses go to the heater core, it would usually make the floor wet on the passenger side (US cars) if the heater core is dumping.

Double check the expansion tank, that could be cracked and also check the hoses that connect to it. You have a simple problem here, take a look around.

[632 Regal]

PS: It is not unusual for the level to drop after driving a while, the V8 self bleeds and sucks more coolant as needed, perhaps just top it off a few times and see how it goes. This is not unusual by any means... yet.

[1995 540i]

ok thanks very much I will have to go out and look once this rain stops since I didnt park the car in the garage, I will get back to you and let u know if anything i find or come up with, the last thing I wana do it take it back to the shop but just might have to since i thought i had the problme fixed.

[1995 540i]

well just got in after a check, seems as if still no sign of a leak, the tube on the bottom right where the coolant leaves or comes into the tank had a little bit of coolant below the clamp, so i did tighten the clamp just a little more, other then that NO signs what so ever of any leaks from any hoses, I will hop in my other car and pick MORE coolant up sometime today (thought I was done with havin to do that) top it off and see what happens there after. Will keep you posted, many thanks for your responce and for your "what to look at & for tips"

[Tiger]

Just top it off and see if it leak anymore. You can add water for a little bit. You don't want coolant concentration too high anyway.

There are alot of places to leak in coolant system... waterpump, hoses, heater hoses, aux pump for heater and radiator. Alot of things leaks at 100,000+ miles.

Look for the telltale white spots... these are coolant leak spots and use your fingers to check all hoses for any wet spots.

There are alot of hidden hoses underneath that reservoir so unbolt that reservoir and move it slightly out of the way to see like 5 hoses.

[1995 540i]

well yes NO signs of any white stuff under my oil cap or anything of the sort. he only has 84k original miles so far, i top him off and took him "travis" for a spin, let him run for 5 mins after i got back. shut him down and check for leaks, nothing then and still nothing now, i will keep u guys posted in the next week or so and keep checkin every now and then at the fluid level and for leaks. again thanks for all your tips and yes i named my car travis...

[Tiger]

White spots... externally... meaning like if your water pump is leaking... and splashes everywhere... when dry... white spots on hoses... etc.

[1995 540i]

oh ok ill check those out as well. thanks