Great guide! It helped me a lot. Just finished. Same model, same year, 56KMiles. Same code, P0128. Car was clearly acting like thermostat stuck open.

One thing I did differently: Draining and saving coolant:

I didn't open red plug on the bottom, I was to lazy to jack-up the car and unscrew all these bolts on bottom protection cover. I figured out it should be possible to siphon coolant from the top. I had siphon from Harbor Freight.
harborfreight.com/fluid-siphon-pump-93290.html
First I cleared expansion tank. I snake siphon as deep into throat of tank as I can. After that I disconnect top return hose from the tank. It's thinner hose that splits from main thermostat hose. Close cap on the expansion tank, connect siphon to the thin hose (I was able to insert siphon hose directly into expansion return. Now prime siphon and help it to drain by blowing air into front nipple of the expansion thank (be creative). That's it. The rest of the process is exactly the same as in the guide above.


I was able to siphon full gallon of coolant, including content of the expansion tank. After that I've main hose disconnected from thermostat. Coolant was exactly at the bottom edge of open thermostat. Use siphon again to drain 2-3 ounces from thermostat. It appeared dry after that. After retracting thermostat be ready to siphon a little more. At this step I did spill a little, maybe 4-5 ounces. I consider it to be negligible. I was ready for it and used stack of paper towels to prevent it from leaking on belts and pulleys.

Took me two hours. It can be done in 30 minutes. MB estimate was "at least" 2.5 hours at $125 per hour. Part - $178. Also must buy new fluid. I'm sure there is more. I found original thermostat from different dealer for $148.
Autozone has wrong part, listed as W203, actually for W202.

It's a shame nobody has just a cartridge. It snaps out very easy. It would be $20 part, like the rest after market thermostats. Oh well, have to do it quick.

One more thing:
Comparing old and new thermostats, they both looks like half-open. Visually I can't find single difference. Yet , new one solved P0128.

Cheers yall!

 

i received this error code and the guy at autozone told me it is a low level coolat. should i assume it is safer to the thermostat?

 

What was the error code?

If the error message is "coolant low", buy some Zerex-G05 (or MB coolant) and add some. If you are only low little, you can add some distilled water, and that should take care of the problem.

 

p0128

 

P0128 indicates that the thermostat is not functioning properly (very likely stuck open). Replacing the thermostat should take care of the problem. Good news is that the part is relatively inexpensive and is relatively easy to replace.

 

P0128 indicates that the engine is failing to get up to normal operating temperature as regulated by the thermostat - usually caused by the thermostat being stuck open - the Benz failure mode for thermostats.

P0128 = Coolant Thermostat (Coolant Temperature Below
Thermostat Regulating Temperature)

Excuse me being pedantic.

 

I'm even pedantier:
must add to definition of P0128 "... in predetermined time", usually function of environmental temperature, predetermined by ECU code.
P0128 may also be caused by faulty temperature sensor. Observing temperature reading history it should be possible to determine if sensor is OK. Or, actually, it does not matter as thermostat assembly includes temperature sensor.

It is possible to get this code if coolant extremely low. As thermostat located at the top of the engine it is possible to have air pocket. In such situation engine may overheat when temperature reading staying low. But I expect that healthy engine, as soon as coolant start flowing, will have nice healthy burp.
After replacing thermostat I had like 15 ounces of coolant left. Run engine for about 20 minutes without cap - thermostat staying cold to the touch and no burp. I decided to do about 15 minutes of city driving, then cool down (DO NOT OPEN HOT COOLING SYSTEM). After that it become thirsty and swallowed leftovers. Now it works as expected and few days past still no code.

Cheers yall!

 

finished it. It helps if another person gives a hand while reinstalling serpentine belt. now i need to delete check engine light, is it possible to do in the display or is it necessary to use OBD scanner?

 

You need OBD or DAS tool. Error code ain't no maintenance warning, can't be cleared from dash.

 

all set now. guy at autozone said they are not allowed to clear lights but it was a one time favor.

 

Just did it today, I jacked up the front of the car to try to make the coolant flow to the back, still lost about a litre of coolant. Only took about 15 min but be carefull with the air intake as mine ripped when i tried to move it out of the way.. who knows why its made of paper. The part cost me $60 from my local auto parts store but its $37 at autohauz. Oh ya, the engine will tell you if the coolant is low, so if its throwing the code and not telling you to check coolant, and you are not getting good heat then its your thermostat

 

Freakin A. I tried to do this also and ripped the flimsy air intake. I gotta go run out and get this part also now. Is this part just the hose or the whole intake assembly?

 

Assuming you have M271 engine,.....

Mercedes Part# 271 090 03 82 "Air Guide Pipe" / Air Intake Hose
Its about $50 and includes the plastic at each end

Probably NOT a good idea to give into temptation and do a ghetto fix,.... using a PVC hose or aluminum pipe,.... the stock fabric seems to absorb moisture before it goes to the paper air filter.

 

Oh well I congratulated you on an excellent write-up and now I think it is my turn to use it....so instead of starting a new thread I am posting it here.

So here is my story, I have 2 C's a C230 2002 and a C280 4matic 2007. I drive the same distance on both ~9 miles to work. The c230 hits 80deg's in about 2 miles, but the C280 stays stuck at ~60-65degs and does not cross the 80deg mark at all so the drive to and from work in the C280 is freaking frigid...so my question to y'all; Is my thermostat on its way south?? Do I need a new thermostat...there is no CEl or any thing....no check engine light nothing...just that it will not go to 80degs for me to feel the cabin heating.....

please any advice is appreciated...

Javvy

 

ok here we go go found a video as well....diffrenet car but exactly the same process..


Cheers....now back to my question...anything??

Javvy

 

The CEL (Check Engine Light) is a function of thermostat and time. I mean if the temperature failed to reach (about 85 dec c) within Predetermined time it will create a Check engine light. So if you don't drive for that predetermined time you will not get that error.

 

aahh good point SK.....I guess I need to take it for a little bit longer drive for the CEL to pop....How much is this pre-determnind time..any idea??

Thanks for all the help....appreciate it...

Javvy

 

It will pop up soon, I noticed that on my car last month and after a week of driving sure enough the light came on. Go ahead and order the part, I got it online form Pelican Parts and it was about $30. Replacing it is very easy, just have to be careful not to spill antifreeze if you don't completely drain it (I didn't and lost about 1/4 of it.

Tim

 

just went to a hard drive during lunch and the CEL popped, so now on to ordering the parts...pelican parts humm....the cheapest I found was $85 for a wahler and a no name brand for $59.99 + $10 shipping no name brand...will check out pelican and see if I can find it for $30....Will be changing the belt too...I am at 100K so might as well replace the belt....

Thank you Sk and funnyent...

Javvy

 

Here is a link to the one I bought. Part number: 271-203-05-75-M2. On their website you can put in the exact model of your car just to make sure it will fit... I think it's the same though.

http://www.pelicanparts.com/catalog/..._pg1.htm#item2

Yeah it's probably a good idea to replace the belt if you're already going to be doing this.

Tim

 

thanks funnyet...but the parts are different, the one for the c230 car is 90deg and the one for the c280 is 100deg and they are completely different parts...thanks for the heads up; when the time comes to change it on my 2002 c230...;-)... way cheaper than the c280....

Picked up the thermostat for $59.99+$9.99 shipp and $15.03 for the belt from ebay....

thank you for all the help and info...

javvy

 

http://www.parts.com/parts/2002/Merc...iagram=5776080

 

thank you VVF, but the c230 AND c280 thermostat are 2 different parts. The C230 is a 90deg theromostat where as the C280 is a 100deg thermostat. Their conestruction and setup is also different..........thanks for the help...;-)

javvy

 

Javvy, if you are not planning to replace the drive belt, it'd be good to not get coolant on the belt. In the DIY, first step is listed as remove the coolant hose to the thermostat. That will result in coolant spilling on the drive belt. My suggestion is to first drop the belt and move it to side. Other than that step, I think it's pretty straightforward job.

Belts can last a long time; however, they START disintegrating soon after oil/coolant spills on the belt. You don't want the belt to break and wrap around the crank pulley while the engine is running.

 

Sorry man... I wasn't paying attention