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. banghead

[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... crazy

[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

[1995 540i]

well seems i still have a SMALL leak somewhere, i did notice however the leek seems to be more only when im running the AC, which makes not sense at all but just thougt id throw that out there. im going to just have to live with it, just keep some extra coolent in the trunk i guess, just wish i could find the problem and fix it. thanks for all your help guys!! if i find anything in the future with it, ill be sure to let you know just what it is or was...

[nk530]

Just something to check, this happened to me: The cross-pipe underneath the intake manifold that leads from the water pump in the front to a manifold bolted to the back of the engine that splits the flow to each bank of cylinders. It's a rigid aluminum pipe with o-rings on each end. In my case, the o-ring at the back of the motor was seeping coolant onto the top of the engine under the intake manifold. The coolant would evaporate off the hot engine and leave no trace other than the afore mentioned white spots (which you wouldn't see without taking off the intake manifold). I was able to diagnose it by shining a flashlight underneath the intake manifold and spotting a small puddle of coolant in the valley. It was also accompanied by a slight coolant smell in the cabin after leaving the car parked for a little while.

...Just a thought.
-Nate

[1995 540i]

Nate-

Hmm, I wont have the time tonite since I have shift at my firehouse but i will check on it Fri. for sure! Thanks and ill get back to you and let u know if I found thats my problem!! just might be...

[shogun]

only drops when aircon is on?
There are 2 drain holes left and right of the center console behind the carpet cover on each side, that is the drain for the moisture created by the aircon system.

That is moisture from evaporator and expansion valve


quote

EVAPORATOR

Located inside the vehicle, the evaporator serves as the heat absorption component. The evaporator provides several functions. Its primary duty is to remove heat from the inside of your vehicle.
A secondary benefit is dehumidification. As warmer air travels through the aluminum fins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. Dust and pollen passing through stick to its wet surfaces and drain off to the outside. On humid days you may have seen this as water dripping from the bottom of your vehicle. Rest assured this is perfectly normal.
The ideal temperature of the evaporator is 32 degree Fahrenheit or 0 degree Celsius. Refrigerant enters the bottom of the evaporator as a low pressure liquid. The warm air passing through the evaporator fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant begins to boil, it can absorb large amounts of heat. This heat is then carried off with the refrigerant to the outside of the vehicle. Several other components work in conjunction with the evaporator. As mentioned above, the ideal temperature for an evaporator coil is 32 degree F. Temperature and pressure regulating devices must be used to control its temperature. While there are many variations of devices used, their main functions are the same; keeping pressure in the evaporator low and keeping the evaporator from freezing; A frozen evaporator coil will not absorb as much heat.

unquote


Automotive Air Conditioning Systems (http://www.familycar.com/Classroom/ac1.htm)