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06-24-2010, 06:40 PM | #1 |
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Checking & adding engine coolant DIY
Hi Guys,
I thought I would create this simply DIY thread for checking and adding engine coolant. Somehow BMW has over engineer'd the expansion tank and level float. It is NOT as simple as one would think. I really don't know why they just did not make the expansion tank out of some opec plastic instead of non-see-thru black stuff! First off.... ALWAYS check your coolant with a COLD ENGINE!!! NOT HOT!!! Ok... here is my little thread... The black coolant expansion tank is located on the front passenger side of the car. as usual... the woners manual has been somewhat lacking - I think. Refering you to the coolant expansion tank directions. Here is a close up photo of the expnsion tank directions... (my coolant was a little low) The coolant expansion tank... lefty loosey.... There is a red float showing you the coolant level... use your finger to push the float level down and watch it "bob" back up to measure the coolant level in the tank... when the engine is COLD it should be LEVEL with the lip of the exp tank. Mine was slightly low. I choose NOT to add any fluid. IF you have to add any coolant... USE ONLY BMW approved coolant!!! |
06-24-2010, 11:32 PM | #2 |
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Nicely photographed as usual David. I'll have to check mine one of these days, but still < 5000 miles on the car...
Without having looked at mine for reference, that diagram stamped into the tank is confusing. Why do the large and small circles change places (height)? That would suggest that the top of the red plastic stick hinges in some way? Does it? Don't really understand looking at that diagram... ianc
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06-25-2010, 05:09 AM | #3 |
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Yea... I don't know why the two pics have a different looking float. I have not checked mine when its hot, for fear of burning myself! I always check it cold. I think that must be a mistake on the diagram regarding the float pic.
When I checked mine... I was kind of surprised that to find my coolant slightly low. I guess this is why some have their coolant light come on. I think our cars must use a little bit of coolant and oil - over time. My only other tip is to make sure the cap 'clicks" when you tighten it back up. |
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06-25-2010, 05:46 AM | #4 |
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Another tip - if the cap is a little difficult to open and close, add some rubber grease to the three o-rings. Keeps them fresh and makes opening and closes VERY easy.
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06-25-2010, 02:04 PM | #5 |
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The diagram on the expansion tank is confusing.
I interpret it to mean that when full the LOWER of the two bubbles on the floating stick should be level with the lip of the filler. That would mean that the HIGHER bubble would be above the level of the lip. That's what the diagram looks like to me - but who knows?? Jack |
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06-25-2010, 04:50 PM | #6 | |
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No, NO! First, you need to check the coolant level when the engine is COLD>! When you check the engine coolant when it is cold it will be at the MIN MARK. So... the top of the"float dip stick" should be FLUSH or LEVEL with the top of the exp tank threads. Don't get too caught up on what the dip stick diagram picture is... I think it is more important to see that the "float di stick" is not lower than the top of the threads of the tank. Like I said in my OP, mine was just SLIGHTLY low. I guess this is why BMW has given us a "low coolant level" warning light. |
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06-25-2010, 04:58 PM | #7 |
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I still don't get it.
Can you pull the red stick up and out of the tank? If so, what does it look like? what do the two circular areas of differing sizes on the stick in the diagram represent? ianc
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06-25-2010, 05:20 PM | #8 | |
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So... checking the coolant level when the engine is cold. The float should be flush(atleast, or higher) with the top of the expansion tank threads. IF the dip stick float is sitting lower than the top of teh threads... your coolant is too low. Atleast that is teh way it looks like it works to me. lol Maybe I should go look at my float tomorrow morning before I fire up the engine. |
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06-25-2010, 10:08 PM | #9 | |
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Will report back... ianc
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06-26-2010, 05:31 AM | #10 | |
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BMW has had it like this for a number of years now.
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06-26-2010, 11:29 AM | #12 |
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Ok... this morning I checked that little red float thing. No you can not pull it out of the res. You CAN move it up and down - and a little bit side to side.
So... it is just as I thought... you don't really need to over analize that diagram bmw puts on the res. Just know that when the float stick is BELLOW the cap threads... you will need to add some coolant mix. But if it is that low your YELLOW add coolant light will come on anyways. |
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06-26-2010, 05:01 PM | #13 |
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Yes, after looking at mine this AM, it's pretty simple. There are two little spheres cast into the stick.
If the top of the lower one is even with the top of the filler neck, you are at max. If the top of the upper one is even with the top of the filler nec, you are at min. If the top of the upper one is below the neck, add coolant to bring it to max. The thing that confused me is that they show the little spheres as two different sizes in the diagram. Why did they do that? ianc
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08-12-2010, 06:53 PM | #14 |
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My coolant light came on today and I'm having a quick look through this now. Seems simple enough but I wanted to check anyway. Thanks for the DIY
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08-13-2010, 04:28 AM | #16 |
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I picked up some BMW Coolant 1.5 litre for $16.25 and some cheap demineralised water $1.09 for 2 litres from the grocery store. I'll do a 50/50 mix in the morning.
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11-21-2010, 04:10 AM | #17 |
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Nice post.
I have read others say that if you do top-up your coolant you need to bleed as well. Is that the case? or is it simply add coolant and it's done. Should the engine be running when adding coolant? i have also read people say the heating should be fully on? Is that another false bit of info? Thanks again |
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12-31-2010, 09:24 AM | #19 | |
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I do not think you need to bleed the cooling system for a simple fluid top up. Maybe IF you had to add say a gallon(4+ liters) of coolant than, maybe. Same goes for putting the heater on full. IF you had to replace a coolant hose or water pump than that would be a different story. Dackel |
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01-03-2011, 11:16 AM | #20 |
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This might be a dumb question-- what is the significant difference between the BMW fluid and Prestone (green) and another orange/red anti-freeze?
Scott
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01-03-2011, 12:58 PM | #21 |
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After reading this thread, I had to look at mine.
With the instructions in this thread and looking at the diagram, it makes perfect sense. BTW, my car is just over 3 weeks old and the top of the red float is about 1/4" below the top (which I assume is where it was when I picked it up - can't believe I need coolant already). This would seem to indicate a low level, but is it really? Has anyone had this condition and added coolant? How much coolant did you actually add to bring it back to normal? (I realize that being only 1/4" below the top doesn't mean I would would be adding a cooresponding tiny amount.) |
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01-03-2011, 07:41 PM | #22 |
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