Why would BMW's need to have coolant topped off?

[Dick Schneiders]

In the latest Bimmer magazine, one of the tech questions had to do with possible leaking head gaskets on BMW's in general. The questioner was asking about several cars that he had come across recently that had head gasket replacements after the owners begun to smell the sweet odor of a coolant leak. He wanted to know if this was a typical weak point of bimmers. The answer from their tech editor was what I would have expected, that this is not a weak point but that it will happen. In the answer he discussed what could cause these failures and one of them was the use of non-BMW coolant or coolant that was not phosphate free, and also not changing the coolant on a regular basis. He also mentioned that head gasket failure would not be the first thing he would think about with the smell of coolant.

The only part of his answer that surprised me was when he said that the newer (I don't know if that includes our E34's) BMW's do require occasional coolant top-off. I have never heard that before. Is this really true? What would be the cause of this? Where does it go?

I have had just the hint of this smell in one of my 1991 525i's this winter, and suspect that there is a small leak somewhere in the heating system. However, I have been checking my coolant level regularly and have not had any problems with loss of coolant, and haven't really had that problem at any time with either of our 1991 525i's.

Thanks,

Dick Schneiders

[Terry B]

In the latest Bimmer magazine, one of the tech questions had to do with possible leaking head gaskets on BMW's in general. The questioner was asking about several cars that he had come across recently that had head gasket replacements after the owners begun to smell the sweet odor of a coolant leak. He wanted to know if this was a typical weak point of bimmers. The answer from their tech editor was what I would have expected, that this is not a weak point but that it will happen. In the answer he discussed what could cause these failures and one of them was the use of non-BMW coolant or coolant that was not phosphate free, and also not changing the coolant on a regular basis. He also mentioned that head gasket failure would not be the first thing he would think about with the smell of coolant.

The only part of his answer that surprised me was when he said that the newer (I don't know if that includes our E34's) BMW's do require occasional coolant top-off. I have never heard that before. Is this really true? What would be the cause of this? Where does it go?

I have had just the hint of this smell in one of my 1991 525i's this winter, and suspect that there is a small leak somewhere in the heating system. However, I have been checking my coolant level regularly and have not had any problems with loss of coolant, and haven't really had that problem at any time with either of our 1991 525i's.

Thanks,

Dick Schneiders

I have had similar problems - I have a 530 and a 540 and both have leaked (small amount) from the valley pan gasket...

Hope that helps somewhat.

Terry

[Bill R.]

safety valve so the heater doesn't blow in the event of an overpressurization and potentially scald someone in the car..
I suspect that the new cap pops off at a low enough pressure and enough volume that you tend to lose more coolant than the old one did..
And since this is just a coolant expansion tank, its not really a coolant recovery tank like those primitive american cars have then if the cap releases pressure its gone and you have to top off periodically. I notice this on mine and don't worry about it since its about 8 ounces every 3 months

In the latest Bimmer magazine, one of the tech questions had to do with possible leaking head gaskets on BMW's in general. The questioner was asking about several cars that he had come across recently that had head gasket replacements after the owners begun to smell the sweet odor of a coolant leak. He wanted to know if this was a typical weak point of bimmers. The answer from their tech editor was what I would have expected, that this is not a weak point but that it will happen. In the answer he discussed what could cause these failures and one of them was the use of non-BMW coolant or coolant that was not phosphate free, and also not changing the coolant on a regular basis. He also mentioned that head gasket failure would not be the first thing he would think about with the smell of coolant.

The only part of his answer that surprised me was when he said that the newer (I don't know if that includes our E34's) BMW's do require occasional coolant top-off. I have never heard that before. Is this really true? What would be the cause of this? Where does it go?

I have had just the hint of this smell in one of my 1991 525i's this winter, and suspect that there is a small leak somewhere in the heating system. However, I have been checking my coolant level regularly and have not had any problems with loss of coolant, and haven't really had that problem at any time with either of our 1991 525i's.

Thanks,

Dick Schneiders

[Dick Schneiders]

safety valve so the heater doesn't blow in the event of an overpressurization and potentially scald someone in the car..
I suspect that the new cap pops off at a low enough pressure and enough volume that you tend to lose more coolant than the old one did..
And since this is just a coolant expansion tank, its not really a coolant recovery tank like those primitive american cars have then if the cap releases pressure its gone and you have to top off periodically. I notice this on mine and don't worry about it since its about 8 ounces every 3 months

[KenB]

That's what I want to know...where does it go? just changed my coolant in the fall, used the blue BMW stuff, have not smelled anything or seen any indication of a leak anywhere. The "Coolant Level" "Owners Manual" message came on yesterday and this morning at cold start, then not again all day after warming up. Looks like it might be a couple ounces low...where did it go???

[Dick Schneiders]

it usually means that your coolant level sensor is starting to cause problems, not that you actually have a low coolant level. The coolant level has to drop most of the ways down to the bottom of the overflow tank before the coolant sensor really sends the message of low coolant, not for just a couple of ounces low. The sensor is a very inexpensive part and is quite easy to replace. Do a search on this here and you should come up with details of how to change it. Otherwise, I wouldn't worry about it too much. The messages will probably come more and more frequently and that is the point when I finally decided to change mine.

Dick Schneiders (2, 1991 525i's)

That's what I want to know...where does it go? just changed my coolant in the fall, used the blue BMW stuff, have not smelled anything or seen any indication of a leak anywhere. The "Coolant Level" "Owners Manual" message came on yesterday and this morning at cold start, then not again all day after warming up. Looks like it might be a couple ounces low...where did it go???

[Unregistered]

In the latest Bimmer magazine, one of the tech questions had to do with possible leaking head gaskets on BMW's in general. The questioner was asking about several cars that he had come across recently that had head gasket replacements after the owners begun to smell the sweet odor of a coolant leak. He wanted to know if this was a typical weak point of bimmers. The answer from their tech editor was what I would have expected, that this is not a weak point but that it will happen. In the answer he discussed what could cause these failures and one of them was the use of non-BMW coolant or coolant that was not phosphate free, and also not changing the coolant on a regular basis. He also mentioned that head gasket failure would not be the first thing he would think about with the smell of coolant.

The only part of his answer that surprised me was when he said that the newer (I don't know if that includes our E34's) BMW's do require occasional coolant top-off. I have never heard that before. Is this really true? What would be the cause of this? Where does it go?

I have had just the hint of this smell in one of my 1991 525i's this winter, and suspect that there is a small leak somewhere in the heating system. However, I have been checking my coolant level regularly and have not had any problems with loss of coolant, and haven't really had that problem at any time with either of our 1991 525i's.

Thanks,

Dick Schneiders

I have had this problem (1991 525si, M50 engine) for over 8 months, looses about a pint every 1000 miles. Needless to say I'm not using BMW antifreeze because of this. Went to a local radiator company who found a few bubbles in the water, the oil is clean. He recons it's common for the head to leak at the rear of the engine. Thinking of trying a small amount of radiator sealant to see if it stops but don't know if I should.... Otherwise I gues I'll just keep topping it up for now.