Temperature needle has a mind of its own!!

[donlv01]

Hello everyone! thanks in advance for any help! I have a MB C350 and a few days ago my car started to act up! the temperature needle fluctuates it goes from 80 to 90! up down, up down none stop! after a while driving the temp goes up 90 to 100 up down...! the same way! at one point its even gotten as high as 115, while i was parked with the car on!! As soon as i started driving on the road the temp would go down to 90 and continue to fluctuate. when this is happening the a/c blows warm!! weird!! this only happens after a while of driving! i have no problems in the morning! the a/c is nice and cold! I checked the coolant level and it was abit low maybe an inch so i added water, but it made no difference!!! I have no idea whats going on!!?? Thanks again guys for the help!

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[RLE]

Originally Posted by donlv01

Hello everyone! thanks in advance for any help! I have a MB C350 and a few days ago my car started to act up! the temperature needle fluctuates it goes from 80 to 90! up down, up down none stop! after a while driving the temp goes up 90 to 100 up down...! the same way! at one point its even gotten as high as 115, while i was parked with the car on!! As soon as i started driving on the road the temp would go down to 90 and continue to fluctuate. when this is happening the a/c blows warm!! weird!! this only happens after a while of driving! i have no problems in the morning! the a/c is nice and cold! I checked the coolant level and it was abit low maybe an inch so i added water, but it made no difference!!! I have no idea whats going on!!?? Thanks again guys for the help!

It's a temp sensor someplace and not an engine defect. The dealer will diagnose and repair at the usual fees.

[xXHotelCrazyXx]

Are your electric fans coming on as they should when your AC is on?

[donlv01]

In the mornings the fans work, a/c works, everything works as it should, but the the needle starts jumpingup and down the fans don't turn on!?? Thanks RLE just wanted to see if anyone had this issue and if they new how much the dealer is going to over charge me... Lol

[xXHotelCrazyXx]

Have you checked to make sure your coolant is filled to the top of your radiator and your reservoir is at the proper level?

[donlv01]

The reservoir was a little low, so I added water I haven't checked the radiator! Let me check that right now thanks for the advise!

[xXHotelCrazyXx]

If air gets into the system and the system is unable to properly pressurize, this is a symptom. Also could be a head gasket.

[donlv01]

Dam I hope not! that sound really expensive!!! Hey to check the radiator coolant level do I have to take off all of the covers where the grill are?? beside the coolant level is there anything else i can check? How much should i more less expect to pay if i take it to the dealership?? And thanks "HotelCrazy"

[acr2001]

Originally Posted by donlv01

Dam I hope not! that sound really expensive!!! Hey to check the radiator coolant level do I have to take off all of the covers where the grill are?? beside the coolant level is there anything else i can check? How much should i more less expect to pay if i take it to the dealership?? And thanks "HotelCrazy"

Unless your coolant level was actually lower than normal (burning coolant) then it is unlikely that this is your problem.

You say it was an inch low. Do you mean it was an inch below the very top or was the coolant right at the top of the clear portion of the reservoir (below the black plastic)? It is supposed to be at that level, not all the way up at the top. Just trying to figure out if it was actually low. Either way, if you never check your coolant it might simply have been that low for years and unrelated.

Here is a photo of what I mean (although your reservoir is probably a different shape) http://www.autopartswarehouse.com/im...pm161312_1.jpg

If you're afraid of the dealer take it to an independent mechanic who has experience with these cars. If it is just the sensor (most likely) it won't be too expensive unless you get ripped off (the dealer usually rips people off!)

[keith100]

Originally Posted by donlv01

Hey to check the radiator coolant level do I have to take off all of the covers where the grill are??

Good question -where IS the rad cap Buried very deep somewhere I guess.

[keith100]

Originally Posted by donlv01

Hey to check the radiator coolant level do I have to take off all of the covers where the grill are??

Good question -where IS the rad cap Buried very deep somewhere I guess.

[donlv01]

actually thinking about it, it was only under the black part maybe a 1/4 inch i added only a little bit of water almost nothing! I just bought this car maybe like 8 months ago and this is the first issue i've had! the guy before me took good care of it, so i think, because he had all the maintenance logged in from mercedes dealerships since he bought the car... Either way ill take it to the dealership in a few weeks, ill use my crappy car for now! I was hoping it was an easy fix, just changing out a sensor or whatnot! Thanks guys for your help

[RLE]

Originally Posted by keith100

Good question -where IS the rad cap Buried very deep somewhere I guess.

VERY difficult to locate.

Right on top of the overflow reservoir on the right side inner fender. In front of the battery. OK, AFT OF RIGHT HEADLIGHT.

[donlv01]

So I called the dealership and i found out that the coolant temp sensor cost $8.00!!! with this news i decided to take in the car to swap the sensor but the labor was $178.00... i was thinking thats not that bad! but when i took it in the manager told me he was going to but the computer for free! just to make sure it was that sensor that was messed up! to my surprise it wasnt!!! it was actually the Coolant Fan!! the fan cost $535. and the labor is $225.00!!! FML!! the good part is that he atleast gave me a discount! im only going to pay $700. for everything!!! I guys im going to have to wait for the rims i wanted... oh well! id rather have my car running good than rolling on new rims!! thats guys for all the help!

[xXHotelCrazyXx]

Told ya to make sure those fans were coming on!

[RLE]

Originally Posted by xXHotelCrazyXx

Told ya to make sure those fans were coming on!

One big fan on the engine side of the radiator.

[xXHotelCrazyXx]

Thats what i meant fans...one big fan inside the radiator.