Having issue with coolant and temp reading
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 428
Likes: 63
From: Auburn, GA
C250 2013
Having issue with coolant and temp reading
I experiencing an issue, here it is, see if anyone has suggestion.
I noticed a month ago some coolant spilled out of the reservoir tank but never has no issue with overheating.
So, I wiped all the spilled coolant, bought a new cap from the dealer and filled the tank to max level with distilled water. After 3 days of driving, there has no spill from the reservoir.
But, there have been an anomaly continuing to have which is still an issue, in the winter days specially, the temp gauge takes 15 minutes or more to get to the 85/90 mark on the dashboard. If I turn the ac to auto while the temp is climbing after starting up and driving the car, the needle starts to drop slowly but eventually gets back to 85/90 mark after a while.
I tested this with and without the AC on while driving on hwy or local using a scan tool and the max it reached was 110 degrees.
Is this the thermostat or the coolant temp sensor? Is the thermostat stuck open?
I noticed a month ago some coolant spilled out of the reservoir tank but never has no issue with overheating.
So, I wiped all the spilled coolant, bought a new cap from the dealer and filled the tank to max level with distilled water. After 3 days of driving, there has no spill from the reservoir.
But, there have been an anomaly continuing to have which is still an issue, in the winter days specially, the temp gauge takes 15 minutes or more to get to the 85/90 mark on the dashboard. If I turn the ac to auto while the temp is climbing after starting up and driving the car, the needle starts to drop slowly but eventually gets back to 85/90 mark after a while.
I tested this with and without the AC on while driving on hwy or local using a scan tool and the max it reached was 110 degrees.
Is this the thermostat or the coolant temp sensor? Is the thermostat stuck open?
Super Member
Joined: Jul 2016
Posts: 502
Likes: 81
From: Newcastle Upon Tyne
W204 C220CDI 2011
Syphon out the coolant from the header tank to minimise any loss. Keep it in a clean container so you can put it back.
This document is for an M272, is that what you have ?
This document is for an M272, is that what you have ?
Last edited by alecmascot; Dec 12, 2018 at 03:43 PM.
Thread Starter
Senior Member
Joined: Nov 2013
Posts: 428
Likes: 63
From: Auburn, GA
C250 2013
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Thread Starter
Senior Member
Joined: Nov 2013
Posts: 428
Likes: 63
From: Auburn, GA
C250 2013
Junior Member
Joined: Apr 2018
Posts: 22
Likes: 8
From: Canberra, Australia
2010 c250 cgi, 2001 Porsche Boxster S
I've replaced the thermostat in my c250. You don't need to remove the air hose between the filter and turbo, just disconnect it at the filter end, then you have enough room. From memory there are several hoses connected to the thermostat, plus a couple of electrical connectors. Reaching all the bolts is slightly tricky - a couple are hard to see.
I drained coolant at the radiator. It's slow, but you don't need to drain it all. If you drain into a clean container you can re-use it, otherwise it's an opportunity to refresh the coolant.
Good luck!
I drained coolant at the radiator. It's slow, but you don't need to drain it all. If you drain into a clean container you can re-use it, otherwise it's an opportunity to refresh the coolant.
Good luck!
