BimmerFest BMW Forum banner

My radiator floating level indicator seems to be MIA (where does it go?)

62K views 36 replies 13 participants last post by  bluebee 
#1 ·
Where does the floating coolant-level indicator go?

I didn't remove it; but it seems to not be in the radiator under the cap.

Where do these things go?

 

Attachments

See less See more
2
#2 ·
Same happened to me at BMW dealer after service on cooling system...I complained, but never got it resolved...I waited until my next cooling system overhaul a few years later and replaced everything, including the expansion tank with new and resolved it. I would replace the entire tank and stick, rather than just the stick alone...not worth the trouble to get in there otherwise....either way, you have to remove the tank IIRC. I doubt the level sensor works at all without the stick present...at least that is my guess. I never had any issues for the 3.5 years or so I went without it.
 
#3 ·
Would be a good idea to replace the tank and radiator, et al.

When my tank split open, at 88k, I did a cooling system overhaul.

I opened up the tank and found that the float assembly was actually rotting away and crumbling, and the float was in the bottom of the tank.
 
#4 ·
The float and the level sensor are not connected...as edjack mentions...his float had "rotted away". When you open the expansion tank's lid and the float is missing, it means that it has broken off and has sunk down into the expansion tank. And that part is NOT sold separately (unlike the level sensor).

Time to replace (the entire expansion tank)...for peace of mind. If the float has given up due to time/stress/temperature/age...then the expansion tank itself will probably not be far behind. :)
 
#7 ·
When you open the expansion tank's lid and the float is missing, it means that it has broken off and has sunk down into the expansion tank. And that part is NOT sold separately (unlike the level sensor).
I appreciate all your help but I'm a bit confused (mainly because I was expecting this to be easy but it got complicated instantly). :(

Are you saying the float rotted away so buying a new leveling switch won't solve anything?

I see #20 in the realoem diagram below is the "LEVELLING SWITCH RADIATOR" (BMW PN: 61318360876, $32.46).

Is that what I'm missing? And, is it attached to another thing (the float?) which isn't sold separately?

What part does the "float" come with then?

 

Attachments

#6 ·
Edjack is right

I had this same problem. I poked around and put off getting it fixed. Last week my radiator cracked and the tank was in serious trouble. Luckily I was parked at the time, and had enough coolant to limp to the mechanics. Get it fixed sooner than later.
 
#9 ·
If you buy an expansion tank it will come with the sensor and stick. eac tuning sells the entire thing for $67. The problem with cooling system stuff is when to stop, as it leads down the path of replacing everything. I would wait until you are prepared to do the entire system...dealing with just the expansion tank, and only to fix the stick is not worth it imo.
 
#12 ·
The leveling switch is on the outside of the tank.
I'm confused by the (new to me) terminology.

I'm deducing there are three parts (maybe four) considered here:
- A float (which seems to come with & inside the expansion tank)
- A visual stick (which seems to attach to the float to provide a visual indication of fluid level)
- A "leveling switch" which seems to be independently electronic to tell the computer what the level of the radiator fluid is.

Is this tri-part assumption above correct?
 
#13 ·
Donna, the float & stick are tied together.
The levelling switch is the level "sensor". You should be able to reuse this one.

As mentioned above, when the you "loose" the"visual" float stick (now I talk 2 parts, but you actually see only one part - the stick), the float and stick have parted.
This is a dangerous situation - the plastic has started to crumble.
There were some posts in the past that state if you change the coolant every 2 years with fresh coolant, the plastic parts will last longer. Not sure about this statement, but I did this and so far only my thermostat failed (stuck open) 2 or 3 years ago. And yes, I know I am due for a complete overhaul, which should include the motormounts to prevent braking the neck of the new radiator.
 
#14 · (Edited)
the float & stick are tied together ...
The levelling switch is the level "sensor".
I'm slowly getting it ... I think ... what I "thought" was a stick was actually #20 in the realoem diagram which is not a stick. All my prior assumptions were based on that incorrect assumption! :(

The realoem diagram actually confused me because it doesn't seem to show the float and stick, only the level sensor, which looks like, a little bit, a float and a stick so now I'm slowly realizing they are probably two separate things (the level sensor at the bottom and the float-stick assembly at the top).

Do I have this right yet?

1. The float & stick are inside the expansion tank (at the top, not at the bottom).???yes/no???

2. Both the float and the stick come attached with and inside an expansion tank when new. ???yes/no???

3. The stick can (apparently) be replaced separately but not the float, so, if the float is gone, the only solution is a new expansion tank. ???yes/no???

4. The float-stick combination is (apparently) not electronic; it's mechanical only and visual only. ???yes/no???

5. In my case, the float, over time, apparently separated from the stick, hence I can no longer ascertain the coolant level by the floating stick.

6. Meanwhile, there is a (totally independent?) screwed-in electronic level sensor on the bottom of that very same expansion tank which is sold separately from the expansion tank (and can be re-used when replacing the expansion tank). ???yes/no???

7. Finally, the solution, for me, is to replace the expansion tank because it comes with a float and a stick (of course, I may decide to replace "more" than just the tank ... but for the purpose of this thread, all that is warranted is the expansion tank. Right? ???yes/no???
 
#18 · (Edited)
There is one sentence in that article that surprises me, which is:

I am fairly sure this sensor works as follows: the coolant level float in the tank contains a metallic "donut", and this sensor must use this (via magnetic field, Hall Effect or ???) to determine the proximity of the float to the sensor. When the coolant level gets low, the float gets closer and closer to the sensor, until the low-coolant alert is triggered...

This implies (but does not prove) that the visual mechanical float is somehow electro-magnetically tied to the electrical level sensor!

So, the bad news is that I can assume that a low-coolant level won't accurately be noticed by the E39 computer ... making replacement of the expansion tank all the more urgent.

Since I don't want the job to get too big for me ... what are the minimum key parts to replace (I noticed "motor mounts" were discussed above, for example)...

PS: This pic from one of my old (March 2008) threads below proves that I used to have that floating stick!
 
#20 · (Edited)
Q: What have you changed in the cooling system so far?
A: Nothing but adding fluid when needed.

Q: And what's the mileage today?
A: 88K miles

Q: Did you flush the coolant every 2 years?
A: Never flushed it ever.

Note: This pic from the March 2008 thread, shows the floating stick was intact at that time but it was slightly off center (which is apparently the first clue it's going bad!).
 
#21 · (Edited)
This goes against my grain ... but in the spirit of doing the right thing ... I'm resigned to the fact that, at 88k miles, I need to do a major overhaul of my bimmer (2002 525i):

DRIVE SYSTEM:
- alternator & serpentine belts (old ones are cracked)
- both mechanical tensioners (something is making a cold-idle noise)
- idler pulley (cold-start noise might be coming from here)
- roller (cold-start noise might be coming from here)
Note: Generally I try to prove a part bad before replacing but I don't really want to rip this stuff out twice as it's my only transportation.

COOLING SYSTEM:
- expansion tank (level float & stick disintegrated somehow)
- radiator (may as well replace it with the expansion tank)
- upper & lower hoses (may as well replace it with the work involved)
- thermostat (may as well with the work involved)
- thermostat housing (may as well with the work involved)
- water pump (may as well with the work involved)
- bleed screws (might replace them with brass screws)
- coolant replacement & bleed procedure
Note: Generally I replace only what's bad but everyone says it's better to replace in the garage than on the road.

SPECIAL TOOLS:
- 32mm thin (8mm thick) crescent wrench for fan nut
- 45mm spacing (4mm thick) pulley nut counterhold tool
Note: Most say you can get away w/o these tools but generally having the right tools is better than not having them.

This is already a bigger job than I ever wanted it to be ... but I may as well ask ... did I miss anything that has to come off anyway that should be replaced?
 
#22 · (Edited)
- 2 hoses from the expansion tank.

- top hose from the expansion tank nipple to the radiator that sits under the fan shroud (15)

- lower hose temp sensor because your cannot find a replacement O-ring and if
you don't replace the sensor, they leak.

- Get the small hose OEM hose clamps (16) for the small hose between the radiator and the
expansion tank nipple. The better fuel line clamps will not fit on the expansion tank nipple
(will fit on the radiator nipple) The cheap worm gear clamps don't clamp well and often
leak. (I know this for fact as I did mine 2 weeks ago) You will need the special crimp tool
for the OEM clamps.

- Buy an extra clip that secures the expansion tank to the shroud. (13) This is the clip the
bleeder screw sits in the middle of. They often break and are cheap.

- I would not buy the leveling switch. They come out easily and should not fail.
They are a magnetic reed switch sealed in glass. It looks fragile but take care in handling and
reuse it.
 
#24 ·
Hi Bluebee.
There are two main hoses that go into your engine from your radiator. The Upper and Lower hoses... Replace both of them, bcuz they have plastic fittings/connectors and they stress with heat over a long periods of time. If this is your car's first major coolant overhaul, then replace it all in one shot. It is easy, but very time consuming, - you should be able to do this within 4-6 hours by yourself, as a first timer. Here's what I've done to mine less than 3 yrs ago. I have replaced the radiator, the expansion tank and overflow tubing which runs over the radiator's exterior and under the fan shroud, also replaced the fan shroud and it's smaller coolant hoses (the fan shroud dry rots/cracks/flakes easily, and it holds other smaller coolant hoses in place), replaced my fan clutch and fan blades (cuz that also dry rots too), my thermostat also (integrated with housing, 1 part all together), my water pump, the coolant.... - And if you feel up to it, replace the idler pulley, the tension pulley, and the serpentine belts (the main belt and the A/C belt). I got most of my stuff thru ebay. I have seen the upper and lower radiator hoses on ebay for $30 a piece for your 525i. The only thing I got from the dealer was the fan shroud... But I now see them on ebay for 50-60 bucks... You may need a fan clutch tool to hold the pulley as you turn the fan clutch nut to loosen it. Most of the time, I can loosen the fan clutch without that special tool - just by going under the car, pulling the serpentine belt tightly with my hand, - while I use a flat adjustable wrench to turn the nut clockwise to loosen it. From there, with your hand, just spin the fan blades clockwise until the fan clutch comes off. To tighten the fan clutch you have to line up the threads just right, and then spin the nut/fan blades counter-clockwise, slowly and evenly, - until it catches. Then you can spin the fan clutch on, by the blades, until it stops. Dont forget to tighten it back up. Since the engine rotates against the fan clutches threads - you wont have to tighten it too much. I always remove the fan clutch first after i take off the serp. belt, and then replace it last followed by the serp. belt, when i need to remove the radiator, or work on the pulleys, water pump, thermostat, etc.... It's just makes makes more room to work with.... One more hint - the lower radiator hose may be hard to pull off, once you have released the securing clip on it (dont forget to unplug the sensor attached to it first). It always gives me grief when i have to take it off. But it will come off ..... :)
 
#25 ·
+1, all great advice except the recommended sourcing (eBay). I have seen too many posts regarding substandard no-name parts (granted mostly suspension) from eBay that have questionable lifespans. The critical nature of the cooling system makes this even more important. My view is that if you are going to DIY, you will have saved substantial money (> 50%) over having a shop perform the work. You will have also invested significant time and effort. The savings you get with an eBay part vs. a branded part is simply not worth the additional risk and uncertainty. Just my .02.
 
#27 ·
Fudman - I hear you loud and clear. I'm very skeptical about buying thru ebay too... And your right about the suspension components. I don't like to go there. However I research where the parts are being made and shipped from... I NEVER buy anything that says "shipped from china", and I also see where the part has originated from. If I'm not convinced, then I keep searching. I bought my Bilsteins and Vogtand springs thru ebay, and 3 yrs later, they work great. Pretty much I go to the dealer to buy electrical parts. Those I'm very scared to buy after-market. BUT, if they are Bosch, Bremi, or other German brands, and I can find them on ebay cheaper, and "new"? - Well guess what? I'm there... I bought a Bosch 140amp alternator, on ebay, for 210 USD... The same EXACT alternator at the dealer costs over 350 bucks. Check this out. If possible, be-friend a BMW dealer parts specialist. I did. You will be amazed on how many parts are after-market parts, and that BMW endorses or "stamps" their name on it and double charge you for that. BMW does not make their "genuine parts", - Bosch, Bremi, and other companies do. I just found out that the BMW cars here in the USA are using GM/Chevy transmissions, if you were to replace the factory OEM. lol I dont know if that is exactly true, but this came from a lead BMW tech that i know... I'm telling you. The thing is, dont get too caught up on the whole "BMW genuine parts" thing. You'll just end up wasting money.
The coolant system parts that Bluebee needs to replace, - I have already replaced on my car - aftermarket. I bought everything from ebay, except the fan shroud; and only bcuz i didnt know better at that time. Till this day, "knocking on wood", I haven't had a problem with my cooling system.

Bluebee - I forgot to mention, dont forget to bleed your cooling system once you complete your work, and before you drive off in your car. You dont want to blow a brand new hose, or radiator!!!!
 
#28 ·
dont forget to bleed your cooling system once you complete your work, and before you drive off in your car. You dont want to blow a brand new hose, or radiator!!!!
For reference (for others reading this), bleeding & refilling procedures are here:
- Bleeding the cooling system (1) (2) (3)
- How to refill M52/M54 coolant DIY (cn90)
- Coolants recommended by BMW and users (1)

BTW, an interesting coolant level anomaly was reported yesterday here:
- Check coolant light, coolant is tad low, but "bobber is full up
 
#29 ·
#30 ·
Just for the record, today someone opened a thread for the same problem:
- Expansion Tank W/O the Float??

Note: If we cross link constantly, then people, when they do their search, will be able to find the information they need more easily. They can start where we left off ... and then add value ... standing on our shoulders.

 
#31 ·
Just today, someone asked how to properly fill the expansion tank when the bobber is missing:
> E39 (1997 - 2003) > Expansion tank level indicator.
Hi there. Just found out that the float level in the expansion tank of my 2001 525i has somehow disappeared inside the tank. Obviously I need to order one, but, in the meantime can anyone measure what the water level from the top of the cap should be so that I can check my coolant level. Much obliged.
 
#32 ·
I'm the culprit this time. Sometimes we can get get confused by our shared language. I reached for the keyboard before a thorough search - sorry. You call it a bobber we say a float, and there are many similar circumstances. I used this same post in a UK forum. What I was really hoping for was someone to measure water level from the top of the radiator with a Stanley rule or tape measure or ruler or some other English word for a measuring device:confused:

The one most important thing about ALL of the forums is the great amount of help and advice and good humour. Many thanks to you all.:):):)
 
#33 ·
I'm going to guess that about six inches is a good number, based on looking at the pictures in this thread. But someone might measure it more exactly for you.

Assuming you get youre xact number, you could get a soda straw, mark off six inches from the bottom, and then align that mark with the top of the expansion tank.

Then, you could blow into the straw. If you feel air, you need to add fluid.
If you blow bubbles, then your fluid level is fine.

You might also be able to just dip a solid rod of plastic or steel down, and pull it back up to see if it is wet on the bottom.
 
#34 ·
It's hard to get an inch-wide rule down into the expansion tank, so, you'll need to use a straw or dowel to tell where the coolant is in most black opaque expansion tanks.

For the record, here's another thread that came to my attention today, with the same problem of a missing coolant level sensor bobber.

> E39 (1997 - 2003) > Coolant reservoir tank missing float stick!
 
#35 · (Edited)
BTW, I added these two links to the bestlinks, and, in doing so, found this humorous (to me) picture ...
- What to do when your expansion tank coolant level sensor float bobber stick is MIA missing in action (1) & how to retrofit a coolant level sensor to an E39 that doesn't have it (1)

What is the mistake?
a) Wrong color?
b) Improper bleeding?
c) Overfilling the coolant?

See also:
- What is the proper coolant level bobber stick height (1) & what to do when your expansion tank coolant level sensor float bobber stick is MIA missing in action (1) & where to find leaks when the CHECK COOLANT LEVEL is lit on the instrument cluster (1) & where does the coolant level sensor cable go (1) & what is the o-ring size for the coolant level sensor (1) & what is the temperature of the coolant when the thermostat opens under normal conditions (1) & how to modify the cooling system expansion tank 2 bar cap to 1.2 bar to vent at a lower pressure (1) & how to retrofit a coolant level sensor to an E39 that doesn't have it (1) & what is the most often recommended coolant (1) & tricks for efficient flushing (1) bleeding (1) and a coolant refilling DIY (1) & some behr/hella cooling system autopsy photos (1)
 
#37 ·
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top