skittles

sunny california started to get chilly recently. but my car went the other direction. every time im at idle/full stop my car strikes at the most 99 degrees. when im running it drops little by little to around 84 to 86 degrees. have you guys ever had this problem? what should i do? i had flushed my coolant also before summer 2009. water pump? air intake? thermostat? radiator cap? im clueless and been so pissed at this..

acr2001

Thermostat.

Glyn M Ruck

Thermostat should open at 87 degrees. Is your cooling fan operating? You could have a blown fuse, faulty fan or temperature sensor. Your temperature is rising the minute there is no air flow as I read it.

Have you used an OBDII scanner to check for stored codes?

TemjinX2

i agree its probably the themostate. You should check to see if the car fan spins at idle when its hot.

splinter

Don’t believe it’s the thermostat as it merely regulates the cooling system’s minimum operating temperature.

~100 degrees Celsius is an entirely normal coolant temperature for any modern engine. Note that the OE unit is only fully opened when in that vicinity. MB cleverly designed theirs to fail while stuck in the ‘cold’ position...manifesting in longer warm-ups.

That it cools to its lowest designed temperature only “when im running” conceivably points to insufficient airflow across the radiator. The fan is typically triggered by the ECU at around 100 degrees Celsius, unless the AC compressor has generated sufficient HVAC system pressure to command same. That’s why many may notice higher coolant temperatures during low-speed cruising in mild climatic conditions. I drive with EC switch lamp illuminated unless it’s sweltering or the windows are getting steamed from excess humidity.

Could be cooling system woes. We’ll need more info to help nail down a proper diagnostic path.
At what temperature does your fan engage?

edit: what Glyn said.

skittles

I use a Scanguage II, so the OBD never leaves my dashboard. thats how i get my accurate readings. and no, theres no codes. I will check fuses when theres some sunlight. i agree it might be an air/fan thing. that was my first hunch. air intake leak was second. and thermostat and water pump was third. what else should i look out for?

Edit: splinter. i havent really noticed the fan so much. i always listen to music. when exactly should it switch on?

skittles

ok. fuse for fan is ok. but doesnt turn on even when i turn on the a/c. relay maybe? how do i diagnose this?

skittles

anyone?

btw karo that esp prob is back... msg me when you get the star! ill drive to you!

TemjinX2

check the relay? maybe hook up the fan to a direct + source and see if it runs.

Glyn M Ruck

The fan is variable speed. My car sits with the temp gauge rock solid at around 90 deg C. If you take a run & then let the car idle with the aircon on it should heat soak & kick in the fan. If it does not you need to be checking fan itself, fan regulator, fuses etc.

skittles

glyn. do you mind posting a blow up on these parts. where they are located. im clueless. im not really driving my car now. im too scared to stall somewhere.

W203E35

Is it possible that the radiator is clogged? When you flushed your raditor did a lot of gunk come out?

The reason I say this is I had a buddy who had a Fod Explorer and his car would over heat (but mainly uphill not idle) and it ended up being that the radiator had gunk in there.

I guess the best way would be the push the car hard and see if temp goes up. I mean if it's clogged then it should go up in high loads not only when it's idling.

Are you sure it's only when you idle? When I get home tonight i'll try to do some research. See if the WIS has any documented problems of over heating.

Glyn M Ruck

These are all I have. The blower fuse is fuse number 51





100 is fan & controller

skittles

thanks glyn. its dark already so ill try to check tom. can i just jump the fan to the battery to test it out?

karo: you know how i drive bro. infact the more i push the car the colder the engine gets. pretty weird. temp only goes up at stoplights. and the ESP message is on everyday now..
and no. there was no gunk. was really clean. just a few particles.

TemjinX2

the bad esp could be a bad throttle actuator. your going to need to pull the codes to be sure.

Glyn M Ruck

Yes you can but disconnect it first or you could blow something.

skittles

BUMP.. neglected the car coz its been so busy.. but today something happened.. went to best buy, 15min drive. parked at 86 degrees took me 10 mins in there went back to the car ant it was 104 degrees.. after a few mins it started to drop back to 86 then the usual fluctuation from 86 when moving to 96 at idle. got home finally popped the hood. fan was spinning really really slow. i pushed it with my finger and it went faster.

SO! conclusion: we all know now its the fan. i just need to know if i can just replace the clutch or is there something else i should look into? or maybe the whole fan? advice ASAP! need this car, this holiday alot..

edit: cant seem to find the controller/clutch or even the fan anywhere. is this a dealer part? ALLmercedes.com has the whole assembly but its freakin $530.

Glyn M Ruck

There is no clutch. I suspect that they only sell the assembly but you need local help on that one.

skittles

eh? local help??? what you mean?

so glyn its 101% my fan right? not a temp sensor or anything else?

Glyn M Ruck

Sorry - I mean local help in maybe finding the parts peacemeal rather than the whole assembly.

No Glyn is not 101% sure it's the fan or controller. It's likely but it could be further back in the circuit. All we know for sure is that the fan is not behaving as it should. Now need to diagnose exactly why.

skittles

oh crap.. so it can be worse.. ill look into the controller first. are these things suppose to be MB only parts? or is there a generic controller?

edit: found this.. http://cgi.ebay.com/ebaymotors/MERCE...Q5fAccessories

if it still acts that way what is the possible next thing to do?

Glyn M Ruck

Check sender unit 146 in the diagram above. Disconnect fan & see if it will run independently from a power source to make sure that the motor is not burned out. Check fuse & SAM as best you can & wiring. Hopefully by elimination this will tell us it's the controller or whatever. I doubt you will find generic parts. Just try and get OE parts at a good price.

Ausmbtech

What engine do you have in your car? The M272 (new V6 has a variable thermostat which increases engine temp when it's cold outside and idling/low loads.

skittles

honestly glyn. im strait dumb and scared to try on how to test the fan. i dint some idle test now. it turn on at exactly 95 puts it down to 90 then shuts off. tired it with the A/C it turns on. but i think we all know that MB fans are one the loudest fans out there. i took a video. also cant find 146..

1st video: start up then fan the fan off.


1nd video: high temp, then fan kicks in.

skittles

M271 sir. but still dont think its the thermostat. observe my video.