W124 Thermostat on way out?

[Charles Morgan]

I think it is, my E320 used to run consistently at 80c, except in heavy traffic, now it is running sometimes at about 70 then without any reason about 90. I assume this is not a job for an incompetent?

Everything else seems fine.

 

[grober]

2 possibilities your coolant temperature is really varying OR your coolant temperature sensor or connection are faulty. I would start by cleaning the coolant temperature sensor connection.

 

[Scott_F]

If the coolant hasn't been changed for a couple of years then it may not be a bad idea to change the thermostat as part of a routine coolant change and radiator flush.

 

[Smiley]

As graeme says the sensor can fail. The only cause for it going DOWN to 70 is either the thermostat or the sensor. Going up to 90 could be the sensor, the thermostat, slightly blocked rad or viscous fan.
Is it completely random or is it related to driving conditions. If completely random then my bet would be on the sensor or the wiring to it.

 

[Charles Morgan]

Thanks all. I would say it started being variable when my head gasket was changed in late January, but I put the lower temperature running down to the fact of changing it. The randomness is a much more recent thing.

 

[d w124]

Charles:If is the thermostat,you can change it yourself.Is very simple,just make sure you use some silicone when you put the new one
I can do it for you if you come round mine one sun

 

[Charles Morgan]

Thanks Dash. I'll see what the consensus brings and hopefully it will be in a position to sort.

The problem with it is that when you expect the temperature to rise, ie sitting in a jam, it does. But it doesn't then come down when you have a good period of normal traffic, which would normally send it back down to 80. However, I only noticed the above 80 bit yesterday before heavy traffic, the below 80 has been going on since the end of January.

 

[krimat2005]

they should run at about 87 deg as far as I know, so even 80 seems a bit low. mine sits nearly halfway between 80/100.

 

[Danny DeVito]

Silly maybe but is there enough coolant in it ??

 

[bolide]

I'd guess it's the gauge. Some of them do all manner of things. My favourite is oil pressure that pegs at 3 when you turn the ignition on... with the engine not turning

Nick Froome

 

[del320]

they should run at about 87 deg as far as I know, so even 80 seems a bit low. mine sits nearly halfway between 80/100.

I might not care to run the engine up to 6k, but, as some may remember, I left the car idling for three and a half hours last year!

The gauge was barely up to 80.

 

[GP801]

Ours runs at 80 degrees in current weather when under load, drops below 80 when taking it very easy. In summer going uphill with a load it will go up to approx 90 and then drop back to around 80 when less stressed.