funnyent

Hey All - I have a CEL and after about 10 minutes of driving, the temp on the car is still below 80 degrees C.

You think this is the common thermostat failure? I haven't had a chance to get the code pulled yet, been busy with work. Just hoping it's something cheap


Thanks,
Tim

Moviela

Code P2181? Thermostat would be my first choice. Next would be the temp sensor.

cvx

The problem could be partially jammed thermostat. Usually the temp. wont be anywhere near +80c with a completely broken thermostat. You can get the OEM 92c thermostat for about $70 / 50eur even from the dealer.

I had similar issue before and it took me over 1h of driving to go above +80. I replaced the main thermostat and the little thermostat (CDI engine has 2). I did not have any warnings/error on my onboard computer though.

Glyn M Ruck

If you can't read Benz codes the thermostat code would be a P0128

Thermostat starts opening at 87 deg C & should be fully open at 90 deg C. If thermostat is not operating correctly the car will run colder than this.

funnyent

Just had the code read, and that's the one! I found a DIY on here and it looks easy to replace thankfully.

I'm a college student and will have to drive home Monday, which is about a 3 hour drive before I can fix this. Will that damage the car or is it ok as long as I don't rev it too much?

Thanks for your help,
Tim

funnyent

So I got my replacement part today, quick question:

How much antifreeze am I going to lose if I don't drain it before I replace the thermostat? I had the antifreeze replaced when I bought the car only 2 years ago and don't want to have to drain it all out.

Tim

Glyn M Ruck

Strage, my post disappeared that said you could drive the car. One or two litres should be OK for top up.