• Hi Guest !

    Welcome to the 500Eboard forum.

    Since its founding in late 2008, 500Eboard has become the leading resource on the Internet for all things related to the Mercedes-Benz 500E and E500. In recent years, we have also expanded to include the 400E and E420 models, which are directly related to the 500E/E500.

    We invite you to browse and take advantage of the information and resources here on the site. If you find helpful information, please register for full membership, and you'll find even more resources available. Feel free to ask questions, and make liberal use of the "Search" function to find answers.

    We hope you will become an active contributor to the community!

    Sincerely,
    500Eboard Management

Where is my coolant antifreeze taking its way??

mb280sel1985

E500E Enthusiast
Member
The past two weeks I've noticed the coolant level warning indicator lamp is lighting up.

Coolant temperature during driving is 80-85C, outside temp is around 25-35F.
Sometimes the coolant temperature needle goes down to 75-78C, but only when not giving throttle over some time.

Yesterday I checked the reservoir, and it was completely dry. I filled it up with 50/50 and had to use about 20 ounces.
But the light wouldn't go away even though the reservoir was full.

Today I drove about 2x25 miles with a resting period of 8 hours in between. No traces of liquid on the ground, or around reservoir.
I checked the reservoir - completely empty. I then filled up the reservoir with another 20 ounces of 50/50.

The light is still lit, even though I just topped off the reservoir.


(Note: the previous owner had to fill up the reservoir with about 50 ounces after sitting for two months)
 
Check under the front passenger compartment carpet pads. Perhaps your heater core is leaking. :skull:
 
Check under the front passenger compartment carpet pads. Perhaps your heater core is leaking. :skull:
Ok, do you mean inside the car under the passenger carpets?

I've noticed a sound from around the dashboard/firewall area, like flaps are opening/closing or something..

where is the heater core located, and how is it related to the coolant level?
 
That's massive coolant loss. Time to inspect the engine compartment closely for any traces of coolant leaks. Assuming you are using the correct MB antifreeze (or G-05), it leaves a chalky white residue at the leak area. Usually it's easy to locate. If nothing is visible up top, pull the lower plastic splash shield and inspect under the engine. And as Derf said, don't forget the heater core; although if the drain tubes are intact, this won't allow liquid onto the carpets inside the car, the tubes exit underneath above the transmission and would drip on top of the transmission. You'll only get liquid inside the car if the foam drain tubes have disintegrated.

Faster method: Fill the system and use a cooling system pressure tester to pressurize to 10psi and watch the gauge. Assuming the pressure drops, observe where the coolant is escaping.

Little known leak point: Check the windshield washer reservoir. If that fluid level is increasing, you found the leak, it's either a bad t-stat on the washer fluid heating coil, or bad O-rings for the t-stat. I've had to replace that t-stat on several cars.

:detective:
 
Little known leak point: Check the windshield washer reservoir. If that fluid level is increasing, you found the leak, it's either a bad t-stat on the washer fluid heating coil, or bad O-rings for the t-stat. I've had to replace that t-stat on several cars.

:detective:
really, is the widshield washer fluid line connected to the cooland line?

Is the t-stat on the washer fluid heating coil inside the windshield reservoir?

Are you talking about the regular termostat, when saying "the potential bad O-rings for the t-stat"?
The termostat was replaced 1 1/2 year ago - and flushed. Don't know what they put on, but I topped it off with blue/green MB bottle from dealer.

The windshield washer reservoir has a washer pump for the headlights, that I have temporarily cut the line to because it was leaking. It has been "clogged" just to avoid leaking windhield fluid.
 
The windshield washer bottle is heated with engine coolant. There is a thermostat inside to control the temperature of the washer fluid. When this t-stat or O-rings leak, it causes engine coolant / antifreeze to dump into the washer bottle.

FYI - the engine temp should never drop below 80°C. If you are seeing 75° at any time with the engine fully warmed up, either the engine thermostat is faulty, or the gauge is not reading accurately. The normal/proper antifreeze is yellow/gold, not blue/green, btw.... but that won't affect temperature readings.


:5150:
 
  • Like
Reactions: Eno
I would like that add that numerous sources have told me this car is a PITA get airless after a refill. Better fill it up completely, squeeze the radiator hoses, close the reservoir cap, start, rev a bit, shut off, re-check.

Also: driving with the warning light lit is - as far as I know - really dangerous.
 
I would like that add that numerous sources have told me this car is a PITA get airless after a refill. Better fill it up completely, squeeze the radiator hoses, close the reservoir cap, start, rev a bit, shut off, re-check.
After draining the system, re-fill via the upper radiator hose first - i.e., pour coolant directly into the engine block. You'll get about 5 quarts in that way (assuming the block was drained). Then reconnect the hose to the radiator, and pour the remaining 4-5 quarts in via the plastic tank. Fill it ALL the way to the metal neck at first, then cap it & go for a test drive until the t-stat opens, at which point the sytem will "burp" and the low coolant light may turn on. Top up the system normally and check it over the next couple hundred miles, it takes a few days for the level to settle out. And keep in mind the factory spec for system capacity is wrong, it's not 16 quarts, it's more like 12 quarts.



Also: driving with the warning light lit is - as far as I know - really dangerous.
In general this isn't a good idea (although unavoidable immediately after a system refill), but as long as there is still liquid in the tank, it shouldn't be dangerous. However if the tank is dry... THAT could be dangerous! I wouldn't drive it far at all in that condition without adding some coolant.


:wormhole:
 
FYI - the engine temp should never drop below 80°C. If you are seeing 75° at any time with the engine fully warmed up, either the engine thermostat is faulty, or the gauge is not reading accurately. The normal/proper antifreeze is yellow/gold, not blue/green, btw.... but that won't affect temperature readings.
:5150:

Could a leaking head gasket cause temperatures at 75° ?

I was assured by the dealer, that the antifreeze concentrate was for all Mercedes cars. I live in North Europe plus we have 5 months winter season up here. Dunno if that may come into play regarding type of fluid.
 
In general this isn't a good idea (although unavoidable immediately after a system refill), but as long as there is still liquid in the tank, it shouldn't be dangerous. However if the tank is dry... THAT could be dangerous! I wouldn't drive it far at all in that condition without adding some coolant.
:wormhole:
ok, but why is it dangerous? Isn't it just a matter of whether or not the engine temperature is kept down at normal operating temp?
Are there other important elements than the engine block, that are impacted by the coolant level?

Note: I guess "completely dry" was an over statement. There was barely visible fluid in the very very bottom of the reservoir outlet to the hose.

The really weird thing is that the coolant level warning lamp still was lit after topping it off. Isn't that strange though?
 
Reminder for myself: put the info gsxr just wrote down into another wiki entry: I think I've seen it numerous times before ;)

Another tip - which the Merc dealer used - was to temporary remove the coolant temp feeler on the top of the engine. You can let most of the trapped air out that way (I believe they only refilled half a liter afterwards).

[sub]Also: quarts? You USA dudes are so confusing in your terms. With the inches, feet, gallons, quarts, squared weather balloons per purple bubble, blahblah :P[/sub]
 
Could a leaking head gasket cause temperatures at 75° ?
Nope.


I was assured by the dealer, that the antifreeze concentrate was for all Mercedes cars. I live in North Europe plus we have 5 months winter season up here. Dunno if that may come into play regarding type of fluid.
It's possible that a newer MB antifreeze may be backwards compatible... but in general, the yellow/gold MB/G-05 stuff should be used.
 
ok, but why is it dangerous? Isn't it just a matter of whether or not the engine temperature is kept down at normal operating temp?
Are there other important elements than the engine block, that are impacted by the coolant level?
There is a risk of hot spots near the top of the engine, in the heads, if there isn't enough coolant to keep the water jacket submersed... could cause all kinds of bad things. The temp sensor is high enough that it may or may not stay in liquid and may not provide an accurate temp reading.



Note: I guess "completely dry" was an over statement. There was barely visible fluid in the very very bottom of the reservoir outlet to the hose.
OK, that's not as bad. :)


The really weird thing is that the coolant level warning lamp still was lit after topping it off. Isn't that strange though?
That would mostly likely be due to a faulty sensor, which should be replaced with a new OE/OEM sensor. If the tank is old & yellow, this is a good time to replace the tank and cap as well. Another possibility is that a wire is broken near the connector at the sensor.

:detective:
 
[sub]Also: quarts? You USA dudes are so confusing in your terms. With the inches, feet, gallons, quarts, squared weather balloons per purple bubble, blahblah :P[/sub]

I'm normally into metrics - 20 ounces = 0.6 liters - so I've topped off a total of 1.2 liters of 50/50 since yesterday.

So you believe I've got air trapped somewhere in the system? Or less air now I guess, since I keep having to top it off..

I really can't see any fluid leaks anywhere, but I will take it in for a complete check tomorrow.
 
There is a risk of hot spots near the top of the engine, in the heads, if there isn't enough coolant to keep the water jacket submersed... could cause all kinds of bad things. The temp sensor is high enough that it may or may not stay in liquid and may not provide an accurate temp reading.
:detective:

Ouch, that doesn't sound nice. Fyi I heard a ticking noise (300 ms interval) from the very back of the engine bay. Didn't sound like it came from the sides, but more from the area around where the ETA butterfly is connected to the throttle cable. Any relevance perhaps?
 
That would mostly likely be due to a faulty sensor, which should be replaced with a new OE/OEM sensor. If the tank is old & yellow, this is a good time to replace the tank and cap as well. Another possibility is that a wire is broken near the connector at the sensor.
:detective:

Anyone have part# for these at hand?

-faulty sensor, which should be replaced with a new OE/OEM sensor.
-old & yellow tank - obviously a new one :).

-other parts that go along? gaskets, etc..
 
I checked the windshield washer reservoir, and it is not contaminated with cooland fluid, so no leak there.

Today the reservoir was pretty much filled up with fluid, unlike the last two days..

I bet the sensor has been broken/intermittent over a longer period.
Could it just be the engine heat making the coolant/water evaporate slowly, and the sensor not hanging in there at all?

I'll keep checking the level the next few days to make sure. I would assume the level of fluid would go down every day, if the conditions are the exact same.. right? Then this would not be a leak, but a sensor not telling what's going on, until it finally broke completely - leaving the warning lamp constantly on - which then made me aware of the low level..
 
Expansion tank = 124-500-15-49
Level sender = 124-540-02-44
Radiator cap = 124-500-04-06

Photo of level sender below. Only get OE or OEM (Hella), do not use an aftermarket sender.

proxy.php
 
Washer t-stat pics:
 

Attachments

  • washer_t-stat0.jpg
    washer_t-stat0.jpg
    35.7 KB · Views: 35
  • washer_t-stat1.jpg
    washer_t-stat1.jpg
    173.1 KB · Views: 36
  • washer_t-stat2.jpg
    washer_t-stat2.jpg
    108.2 KB · Views: 22
  • washer_t-stat3.jpg
    washer_t-stat3.jpg
    76.3 KB · Views: 16
  • washer_t-stat4.jpg
    washer_t-stat4.jpg
    40.5 KB · Views: 15
The senders are very cheap to buy the factory unit. Get the O-ring (I believe the sender comes with the o-ring, but I ordered an extra one just in case), and it's advisable to also get a new circlip too. If your expansion tank is all brown, it's a good idea to replace it -- and the radiator expansion tank cap -- at the same time as they are inexpensive and dramatically improves the look of the car underhood. The sensor/sender and o-ring are the same parts used on the later W126 cars, too.

Kindly see this thread for more information.

Cheers,
Gerry
 
Forgot to post a photo of the 500E coolant tank, old vs new:

proxy.php
 
I don't want to hijack this thread, but I do have something that might be related: the windshield washer reservoir doesn't get heated at all. Should I just go ahead and order all these parts, just in case?

Also: does the "old" coolant tank have any value for those who want their car completely stock? Or is it a typical replace part?
 
Also: does the "old" coolant tank have any value for those who want their car completely stock? Or is it a typical replace part?
Just replaced mine yesterday! To be honest nothing wrong with it but just to make it look new:sniper:....sometimes i wonder why we do this when really we can save such cost for something that will go wrong instead. Just what you are experiencing, JB and many of us here, if you're not careful these cars can clean you out!!
 
Last edited:
I don't want to hijack this thread, but I do have something that might be related: the windshield washer reservoir doesn't get heated at all. Should I just go ahead and order all these parts, just in case? Also: does the "old" coolant tank have any value for those who want their car completely stock? Or is it a typical replace part?
Do you mean your washer reservoir never warms up, even in cold weather? Assuming all the plumbing is intact, that could be a bad washer t-stat as shown in the pics above. The original coolant tank is not worth saving, IMO, unless it was a no-miles concours show car. There is a silica pack inside the plastic tank that is sacrificial, i.e. the tank really should be replaced every 10 years or so even if it's not leaking.

:spend:
 
Do you mean your washer reservoir never warms up, even in cold weather?
Yep, was freezing a bit back, and I didn't have water to spray on the windshield :-/

Uh - what are those two large hoses coming out under the airbox on the passenger side
His gas installation :) There's more junk under the airbox, they even had to put a bit of cardboard around the MAF so it fits nicely on the airbox. Very interesting.
 
I should mention...if you buy a Meistersatz coolant level sensor from Autohaus, the o-ring that comes on it is too small to seal. It doesn't come with a country of origin on the sensor or packaging. A new OE O-ring will be required.
 
Yep, was freezing a bit back, and I didn't have water to spray on the windshield :-/

Oi...My water came so hot on the screen- i thought something is burning...by minus 12 :)

Uh - what are those two large hoses coming out under the airbox on the passenger side, in the photo below? They look like heater (coolant) hoses for something...?

I´ve got LPG. Maybe it´s from there...
 
I should mention...if you buy a Meistersatz...It doesn't come with a country of origin...

LOL! Meistersatz That's one helluva play on words. Gotta be Chinese origin. Credit for their sense of humor. The term can be defined many ways, including Master Fake!:seesaw:
 
Expansion tank = 124-500-15-49
Level sender = 124-540-02-44
Radiator cap = 124-500-04-06

Photo of level sender below. Only get OE or OEM (Hella), do not use an aftermarket sender.
So these I should replace:

Expansion tank = 124-500-15-49
Level sender = 124-540-02-44
Radiator cap = 124-500-04-06
Windshield t-stat = 126-830-07-84
termostat O-ring = 140-997-06-45

Any other parts I definitely should just go ahead and replace while I'm at it?
 
So these I should replace: Any other parts I definitely should just go ahead and replace while I'm at it?

Expansion tank = 124-500-15-49
Level sender = 124-540-02-44
Radiator cap = 124-500-04-06
Windshield t-stat = 126-830-07-84
termostat O-ring = 140-997-06-45 <-- NOTE: Quantity 2 required!

The only other item would be the engine thermostat, if it's more than 5-7 years old, or not OE (Wahler), or if your engine temps are below 80°C when fully warmed up. The upper radiator hose is another item that's good to replace every 10-15 years as it deals with the highest temps & pressure of all the cooling system hoses. Only get an OE/dealer upper radiator hose, btw, all the aftermarket hoses are shaped incorrectly and may rub the p/s reservoir.

:5150:
 
termostat O-ring = 140-997-06-45 <-- NOTE: Quantity 2 required!
Thanks for heads up!

The only other item would be the engine thermostat, if it's more than 5-7 years old, or not OE (Wahler), or if your engine temps are below 80°C when fully warmed up. The upper radiator hose is another item that's good to replace every 10-15 years as it deals with the highest temps & pressure of all the cooling system hoses. Only get an OE/dealer upper radiator hose, btw, all the aftermarket hoses are shaped incorrectly and may rub the p/s reservoir.

:5150:
The engine thermostat was replaced 1.5 years ago.

My engine temps are rarely below 80°C - but it occationally happens when I drive in slow downhill traffic and outside temps are 0°C to -5°C.

On the other hand I've had engine temps at break point for fans to kick in at 107°C. This is in heavy traffic at slow speeds 5-15 km/h. The engine temp almost never get above 90°C if the ASR light is OFF, but when it's ON it rises to 107°C fairly quickly 10-20 seconds.

The upper radiator hose; is it this one: 129-501-26-82? ..and is there 1 or 2 I'll need?
 

Attachments

  • imgdsply.JPG
    imgdsply.JPG
    19.1 KB · Views: 207
The upper radiator hose; is it this one: 129-501-26-82? ..and is there 1 or 2 I'll need?
That looks similar, but it's the wrong part number... you want to order 124-501-92-82 for the 500E upper radiator hose. Remember, only get OE "Genuine Mercedes" for this item. Actually, for everything in that list, only get Genuine MB parts. The sender and O-rings are available aftermarket but trust me, you don't want the aftermarket versions of those (except the Hella-brand level sender, which is ok). The tank and t-stat are not available aftermarket, they will be OE only. The radiator hose is $31 USD list price in USA, not sure what it will be in Europe.
 
gsxr: I saw you post in a different thread, that a new radiator is part# 124-500-03-02. Does this go for all 500E/E500's?

When should one replace the radiator. Is it a big job if it is done meanwhile doing this list?:

Expansion tank = 124-500-15-49
Level sender = 124-540-02-44
Radiator cap = 124-500-04-06
Windshield t-stat = 126-830-07-84
termostat O-ring = 140-997-06-45 (X2)
upper radiator hose = 124-501-92-82

Another thing - is it true the coolant auxilary pump causes high temps when heavy traffic if busted/bad?
Does the coolant auxilary pump have one part# for all years?
 
The coolant auxillary pump causes low cabin heat at idle when it goes bad. I dont believe it affects the coolant temp in any way. When mine went bad the only symptom was poor cabin heating at idle.

I am sure Dave/Gerry will get you a part #.

Andy
 
The windshield washer thermostat? It's inside the windshield washer tank.

See #27 on the attached diagram. It attaches to the bottom of the coiled piece that fits inside of the washer tank (which is where the hot coolant goes through to keep the washer fluid defrosted). You have to carefully extract the coiled mechanism from the tank to access the valve. Note also the two O-rings (#28 on the diagram) that Dave mentions above, which should also be replaced too !!

This part is applicable to all of our E500Es as well as other W124 models. For this particular situation, I happened to have the E320 wagon pulled up on my EPC, and it is installed on all E320 wagon (124.092) models after VIN ending in F184896.

It should be appropriate for ALL 500E and E500 (124.036) models produced.

Cheers,
Gerry
 

Attachments

  • tstat.jpg
    tstat.jpg
    69.6 KB · Views: 19
gsxr: I saw you post in a different thread, that a new radiator is part# 124-500-03-02. Does this go for all 500E/E500's?
Yes, that is the correct part number, it fits all years of 400E/500E, .034/.036.


When should one replace the radiator. Is it a big job if it is done meanwhile doing this list?:
Expansion tank = 124-500-15-49
Level sender = 124-540-02-44
Radiator cap = 124-500-04-06
Windshield t-stat = 126-830-07-84
termostat O-ring = 140-997-06-45 (X2)
upper radiator hose = 124-501-92-82
The radiator should be replaced if it is leaking, and it doesn't hurt to replace it proactively after 15-20 years even if it's not leaking. Replacing the radiator is a medium DIY, don't forget to clamp off the ATF cooler hoses or you'll have a big red puddle. While the radiator is out, clean the condenser fins with a brush and compressed air. And don't use more than 6 quarts of MB/G-05 antifreeze when re-filling the system, as the factory spec is wrong on the coolant capacity (think I've mentioned this multiple times, but just in case!).


Another thing - is it true the coolant auxilary pump causes high temps when heavy traffic if busted/bad? Does the coolant auxilary pump have one part# for all years?
Andy is correct - the aux pump only affects cabin heating performance at idle. Part number is 001-835-13-64 and it's a real nuisance to replace due to limited space to access the blasted thing. Same part number for all years.


:banana1:
 
Just to be sure, before I do this --- I should use approx 5 to 6 quarts of Mercedes yellow/gold antifreeze, mixed with approx 6 quarts of distilled water, when refilling the coolant system in this car?

What does a bottle of the Mercedes antifreeze cost, ballpark? Does it come in quarts or gallons?
 
Just to be sure, before I do this --- I should use approx 5 to 6 quarts of Mercedes yellow/gold antifreeze, mixed with approx 6 quarts of distilled water, when refilling the coolant system in this car?

What does a bottle of the Mercedes antifreeze cost, ballpark? Does it come in quarts or gallons?

There is good info here on how to refill and how much..... http://www.500eboard.com/forums/sho...drivers-and-pasangers-sides&p=31274#post31274


I just bought Zerex G05 for $13 a gallon ... Edit it was $16 a gallon
 
Last edited:
Just to be sure, before I do this --- I should use approx 5 to 6 quarts of Mercedes yellow/gold antifreeze, mixed with approx 6 quarts of distilled water, when refilling the coolant system in this car?
Basically, yes. It's handy to pre-mix to your desired percentage and pour in the already-mixed solution. If you live in a warm climate (that rarely if ever goes below freezing) you can use a slightly lower percentage, as long as you don't travel with the car to sub-freezing temps.


What does a bottle of the Mercedes antifreeze cost, ballpark? Does it come in quarts or gallons?
Typical is $15-$25 per gallon, depending on if you get Zerex G-05 (either 100% or 50/50 premix), or the Genuine MB stuff. The MB yellow antifreeze is p/n BQ-103-0002 and current MSRP is $23.50/gallon.

Note that MB recently replaced the yellow coolant to a new blue stuff (allegedly the same as BMW has been using for years), and you may not be able to get the yellow antifreeze from the MB dealer once their old stock is depleted. From the little I've read about the blue stuff, I personally would not use it in my cars. The blue is p/n BQ-103-0004, same price, $23.50/gallon MSRP.



Thanks, Karl! Skip to post # 13 in that thread.



I just bought Zerex G05 for $13 a galon
I paid $18 for a gallon recently at CarQuest. Note that G-05 comes in both 100% and 50/50 pre-mix, and the price is different... make sure you check the label carefully:

50/50 Pre-mix:
http://www.amazon.com/Zerex-ZXG05RU1-G-05-Antifreeze-Coolant/dp/B0033QQ4VW/

Full strength:
http://www.amazon.com/Zerex-ZXGO51-G-05-Antifreeze-Gallon/dp/B0033QNZZ0/
 
I think Stu Ritter qoutes in the W124 bible, that you should use "pottable water" and not distilled. The formulation is designed to balance with minerals from the tap water. He's a chemist and gave a short lecture on how not to use distilled water and why. Cannot remember it though...



Michael
 
I think Stu Ritter qoutes in the W124 bible, that you should use "pottable water" and not distilled. The formulation is designed to balance with minerals from the tap water. He's a chemist and gave a short lecture on how not to use distilled water and why. Cannot remember it though...



Michael

Potable water is just water that's safe to drink (e.g., tap water). That's good that he takes that position because I have never used distilled water since I realized that it was going to be very difficult getting all the tap (garden hose) water out of the block anyway after a cooling system flush. Besides, radiators are cheap.
 
Distilled water is fine, and older MB factory literature actually specified distilled water as being acceptable. HOWEVER. It MUST be used with antifreeze! You cannot use plain distilled water (obviously only in hot climates) as bad things will happen. The antifreeze acts as a chemical buffer for the distilled (pure) water. Soft water also isn't a good idea, I just use distilled, it's easy & cheap.

The blue antifreeze did not have a good record of reliability with plastic cooling system parts in BMW's. I think the blue stuff is G-48 and is nitrite-free, while the old yellow G-05 was low nitrite. There's no significant advantage that I can find for the blue stuff in our "old" cars, so I'm sticking with the yellow G-05.

:seesaw:
 
The Old-Skool pinkish-yellow (Zerex G05) MB coolant is now well over $20 a gallon. I bought some about a year ago at my stealer and about keeled over when I saw the bill.

I remember when it was around $12 ... not that long ago.

I always pre-mix it and keep it on hand. Once upon a time I was anal about using distilled water. Now I just use filtered water from my refrigerator's water dispenser !!

By the way, that Stu Ritter "Mercedes 124 Bible" should be taken with a grain of salt. Anything pertaining to an 034 or 036 - ALWAYS consult this site first !!

Cheers,
Gerry
 

Who has viewed this thread (Total: 1) View details

Back
Top