Mercedes C180 Coupe (Petrol) -Temperature Gauge

[Jackwong]

Hi All,

I am not an expert on cars at all , so wondered if you could help me.
I drive a Mercedes c-class coupe 2014 plate, and have had no problems with my car at all.

The engine temp has always been at 90 degrees when driving. on Friday I noticed it go up to the 100-120 mark and then back down to 90. It did this a couple of times on my journey back from work. It literally went up for a second and then down again. So it never stayed at 120 . Literally a matter of seconds.
I left it And checked the coolant tank under the bonnet. It was at the correct level.

Over the weekend I drove the car around town and had no issues. The second I go to circa 60 /70 mph the gauge goes up again and back down to 90. I hear the fan running at full cooling the engine down. No warning lights or anything on my dash.

I have booked in at Mercedes for next Thursday. I just didn’t know if anybody has had experience of this or know what it could be. This is the first issue with my car since I bought it 3 years ago.

 

[John Laidlaw]

Sounds like the thermostat ready to fail, oh and welcome to the forums

 

[Jackwong]

I was thinking that, but if it was a thermostat wouldn’t it be cool and not “overheating” as it says on the gauge. When Really it’s not?

thank you mate

 

[Steve@Avantgarde]

The thermostats are a common failure on this engine, we have replaced a few now, they break up inside.

 

[Jackwong]

The thermostats are a common failure on this engine, we have replaced a few now, they break up inside

thanks Steve,

but if it was a thermostat wouldn’t it be cooling and not “overheating”
I’m booked in on Thursday at merc £110,( for the diagnostic. How much would something like this cost to fix

 

[EmilysDad]

I was thinking that, but if it was a thermostat wouldn’t it be cool and not “overheating” as it says on the gauge. When Really it’s not?

thank you mate

depends whether fail open or closed

I'd refuse to pay a dealer that kind of money to diagnose a fault. (especially when Steve says they're a common failure)

 

[John Laidlaw]

^ this- a 2014 car would be better served at a Mercedes Independent specialist not main dealer with main dealer pricing. I'm not completely up to date but an 'indy' would charge in the region of £60/£65 for a diagnostic , although as Steve says there's probably no point anyway they'd change the thermostat...

 

[Mr Greedy]

I don't know about your car, but I have had this on another make of car immediately after a coolant change, which I attributed to airlocks. A quick blast up the road at 7000rpm for literally a handful of seconds and a hundred metres, and then topped the coolant up as some airlocks had obviously been shifted due to a drop in the coolant tank. Didn't see the rapid temperature fluctions again, which were exactly as you described.

Are you able to follow the coolant airlock bleed procedure for you engine if it's not 'just drive it' and immediately top up?

 

[Jackwong]

^ this- a 2014 car would be better served at a Mercedes Independent specialist not main dealer with main dealer pricing. I'm not completely up to date but an 'indy' would charge in the region of £60/£65 for a diagnostic , although as Steve says there's probably no point anyway they'd change the thermostat...

I’m very particular , I know it might cost more but I’d rather do it that way. I’m in on Thursday, I hope it’s in and out haha

 

[EmilysDad]

I’m very particular , I know it might cost more but I’d rather do it that way. I’m in on Thursday, I hope it’s in and out haha

anyone would think that you get better service at a dealer .....

 

[Jackwong]

anyone would think that you get better service at a dealer .....

It’s just a personal preference. I’ll let you know how I get on