NorCal124

Ok, I've now flushed my radiator, added cooling additive, installed a new fan switch, and installed a lower temp thermostat. I've seen some progressive results in my cooling but now I want to make my fan active at a lower temperature. Does anyone know how to go about doing that or what parts I need to get that done? I've heard there was a DIY thread on the topic but I am having difficulty finding it.

ksing44

There is a plug and play modification to have the fans come on at a lower temperature, but I have not tried it yet. See link below for detailed information about the DIY modification and the plug and play part you can buy.

http://pages.prodigy.net/jforgione/MB_CTS.html

Where did you get a lower temperature thermostat? My car has been running a little hotter since the dealer installed a new water pump and thermostat. Now my car typically runs around 90 to 95 degrees, but I liked it better when it ran around 85 degrees. I was thinking about trying to get a lower temperature thermostat, but I couldn't locate one and members of the forums were convincing me that Mercedes intended the car to run at my current operating temperature. They say Mercedes would have used a different thermostat, if they wanted it to run cooler. I am definitely not an expert, but I still don't like the idea of the motor being so hot. I also hate the way the temperature goes up when sitting in traffic. I think it would be great to have the fans come on before 110 degrees. I think it certainly wouldn't be a bad thing to have the fans kick in at say 100 degrees.

NorCal124

I bought it at the auto parts store where I work. Most places have them but you will most likely have to special order it. I bought the lowest temp thermostat they had, 160 degrees farenheit. I don't know how that translates into celcius but I see a big improvement in the cooling system. The car will get hot if you let it but for the most part it stays cooler longer.

oliverb

I also did not like the idea of my engine going above the 100 C mark in stop & go traffic. Found that the car also seemed to idle a little rougher as the temp increased. Other cars I have had seemed to have rock solid temp regulation with very little fluctuation between hot or cold days, heater or AC operation.

I have the MB stock thermostat, the 92 degree "Cool Harness" as described in the link above, and "Water Wetter. I have had the "Cool Harness" installed for more than two years. This is the third summer and I am very pleased with the results. At just about exactly 92 as seen on the dash gauge the fans come on. Engine temp. never goes above 100 - even on 95 degree days with AC on in stop-n-go traffic! I could have made my own but didn't have the time then. I think the 95 degree "Cool harness" would also be a good choice - fans wouldn't come on quite as soon or as often.

The "Water Wetter" was added just under two years ago with the last flush and refill. The concept makes sense to me. Have recently seen posted comments that "Water Wetter" has some oil in it that coats the inside of the passages and that this might somehow not be desirable. Have not confirmed this with the manufacturer. The post said that "Purple Ice" does the same without the oil additive. I have not researched "Purple Ice" for comparison.

ofer

I PUT A 1.2K OHM 1% 1/4W RESISTORS ACCORDING TO THE INSTRUCTIONS
AT THE WEB SITE http://pages.prodigy.net/jforgione/MB_CTS.html
AND IT JUST PRFECT. THE TEMP. IS AROUND 95 CENTIGRADE EVEN IN A
43 CENTIGRADE DAY.
IT'S JUST GREAT AND TAKE 15 MINUTES JOB WITH SOLDERING IRON.
MB RECOMMEND THAT THE IDEAL WORKING MOTOR TEMP. IS 90 CENTIGRADE.

ML55CLA45

he guys... is replacement of the thermastat an easy DIY.... is their any links... pictures.... part numbers and any advice on how to do so?

-Thanks
charles

ofer

the replacement of the thermostat is a easy job. just three screws,
taking up the thermostat cover and pull up the thermostat.
put inside the housing the new thermostat, put a new rounded rubber at
the thermostat cover and thats it.
dont forget to take out the air, by turning the air screw at the top of the
thermostat cover.
i put a replacement thermostat of 78 centigrade.(the MB orginal was 87 centigrade).

ALL THE THERMOSTAT JOB MUST BE DONE WHEN THE ENGINE IS COLD.

ML55CLA45

thanks.... but where exactly can i find the therm... i have no clue... where to start... my car is a 94 e320

-thanks

cap'n jasper

One important tip.....only use MB coolant.

shadowgriffen

with all due respect, may I ask why it is so imperative to add MB coolant only?

AMGDave

Mercedes coolant ONLY... also Zerex G-05, which is the same formula. Full details are in this PDF file (0.6MB)...

http://www.w124performance.com/docs/..._Confusion.pdf

Also, installing a low-temp thermostat is a REALLY BAD idea. The thermostat does not reduce engine temps above 100C, it simply sets the MINIMUM operating temperature. If you are getting temps at 80C or below on the gauge you are wearing your engine prematurely, wasting fuel, and losing horsepower. Optimum temps are (IMO) in the 85-95C range. Usually there are other reasons why temps are high... dirty condenser or radiator fins, crud between the rad & condenser, bad radiator (cold spots), or bad fan clutch. If you have an M104 or M119 engine, you can use JimF's modification to run th electric fans sooner, this works great, I have that mod on my E500. Doesn't work on OM60x or M103 engines though (these have simple, fixed-temp on/off switches).

On a side note, aftermarket thermostats have been known to be flaky and sometimes provide abnormal temps, in more than one case an OE/dealer thermostat reduced temps compared to a new aftermarket (but OEM!) unit from Behr/Wahler. Don't ask me why...

Holson

Even in the hottest days this summer, as long as I had my A/C on the water temp gauge never touched 100*C.

It's got MB coolant and some water wetter.

Once the A/C is off, the needle seems to hover at 100* or slightly less unless I start moving.

I'm guessing the fact that the aux. fans are on at low speed when the AC is on helps cool it down.

What's weird is that, the fans used to come on at high speeds once in a while (Above 115* or somewhere around there). After I had the coolant flushed and added water wetter, it never did again. In fact, I never heard the fans come on at high speed after the first year I owned it.

oliverb

AMGDave;
"If you have an M104 or M119 engine, you can use JimF's modification to run th electric fans sooner, this works great, I have that mod on my E500. Doesn't work on OM60x or M103 engines though (these have simple, fixed-temp on/off switches)."

I have this modification on my 1990 300E 2.6 (M103) and it certainly does work! Fans come on earlier and run until temp again drops below set point - in my case 92 degrees. Don't know about earlier years.
OliverB

neanderthal

the system is pressurised. that raises the boiling point of water. so does using coolant/ antifreeze. why people are so fixated on the temps being near 100 i dont know.

the engineers in germany knew what they were doing. leave it alone, unless you know better than they do. in which case, why arent YOU working there?

before i had my head rebuilt i used to just watch the gauge, and when it got past 115 is when id turn on the heater full blast for a minute or two, and itwould settle back down. now that the head has been done i check the level and thats it. the temp sometimes gets to 110 (its been really hot in southern california lately) but the fans kick in and it cools down.

now if your cooling system is marginal, please feel free to ignore me. if its predominantly warm where you live use more water than antifreeze, and your car should be ok. water dissipates heat but antifreeze does not.

AMGDave

Hmmm... perhaps that doesn't apply to earlier years. That's REALLY strange, though. On the early 124's (gas OR diesel), the electric fan is only triggered on low speed by refrigerant pressure, and triggered on high speed by a thermal switch that engages at 105°C (and this is not a resistance-type sensor). I was fairly certain the change to the temp-sensing fan trigger (instead of a simple switch) did not arrive until the CAN (control area network) computer setups, which were used on M104/M119 engines in the W124. Might need to look at the electrical schematics again...

ashman

The only modification I have done to my cooling system was a new radiator a few years ago. everything else in it is stock, and the needle rarely gets over 100 degrees.

Mostly it hovers just over 80 degrees probably around 83-85.

I run one gallon of mb coolant and the rest is water.

Even with the AC on, and idling in traffic it still stays around 100c sometimes a hair over 100c, but once driving it goes back down to normal.

I don;t think using different thermostats is a good idea. in the long run.

If you are experiencing high temps, this is most likely due to one of the following or a combination.

1. Incorrect mixture of coolant and water (I.E. too much coolant or not the right kind. I only use the mb coolant.)
2. Old radiator which has built up some clogging restricting the flow of the fluid.
3. Water pump is not pumping enough fluid
4. Thermostat is getting old and not opening enough
5. Electric fans are not operating properly.

If all those are working right and everything is in order, you should be fine on temperatures.

But if one or more of them is not working right, then you will probably see abnormally higher temperatures.

you should change your coolant every one to 2 years. I change mine every 1.5 years, and all is well.

Even int he hot weather we have had lately here in so cal, my temp has not been affected by more than a few degrees.

AshMan

NorCal124

Out of curiosity, does anyone know if green coolant can be mixed with the "mb" brand coolant despite color difference?

RobertG

You should never mix coolant with other types.That can create acids and damage parts.

AMGDave

Sounds like someone did not read the PDF file that I posted a link to (see above).

ML55CLA45

as stated earlier in this post... ive been having some cooling problems... it had been suggested that i change my thermostat since its still the original....

well it turns out that when i got my radiator changed at the dealer... they freaking installed my aux fans wrong.... the fans were blowing out... and not in........

thanks for all your guys help-
carino

AMGDave

ROTFLMAO!!!!

cap'n jasper

Got an even better PDF file from a UK forum.
ONLY USE MB COOLANT

NorCal124

the reason i ask is because when i purchased my car it came w/ the standard green coolant. even if i throughly flush the green fluid and refill it w/ the red mb coolant i still run the risk of it mixing. my initial thought was that the green coolant will suffice since, to my knowledge, there was no red coolant in 87' (year of my mb).

AMGDave

Cap'n, THANK you, that was the article I was originally thinking of, but I couldn't find on my own website (how embarassing). That one is specifically about MB coolant. The article I linked to before is a generic article on various different coolants. I have since located my copy of the MB article... same PDF as your link, but it may load faster since it's on this side of the pond:

http://www.w124performance.com/docs/...ze_article.pdf

I don't know what year Mercedes first started using their special formula but it was at least since the early 90's if not the 80's. Also, it's not red (or blue), the proper stuff is a very light yellow/gold/amber color.