Thermostat W123

[fatherpierre]

My 1985 W123 230E (gallery) runs, starts beautifully and gives great fuel economy. She does, however, show low temp on normal running and in these recent cold days doesn't put out much heat.

The temp guage on cold days doesn't get much past 60 with the heat on, and it only gets properly warm when left at idle for ages. I've had many 123s and they normally rest @ 85/90 but this settles at 60ish.

Simple thermo replacement? I also noticed the fan kicking in late one time - but this was on my drive home from buying, and have been lucky in that I don't sit in traffic where I live now!

No cack in oil/water; fan does work; FSH - blah blah blah. It has never reached temp (other than idling) even @ high speed.

Anthing other than thermo I should consider? Ta

 

[vijilants]

If it isn't reaching operating temperature, thermostat replacement would be the first thing to do.

 

[jaymanek]

yes change it.. they are cheap..

 

[fatherpierre]

How cheap???

Just looking through the masses of history and have found photo copies from a Haynes book re changing it, so the last owner obviously thought the same but didn't replace it.

 

[jaymanek]

well if the car has sat for any period, even a newish one can seize up...

Genuine MB one from MB £11.95

 

[fatherpierre]

Just looked on Eurocarparts and they are quoting £63????

 

[jaymanek]

huh! no way... mines a 200 but the same basic engine, cant be that much in it!

I bought mine from Mercedes Milton Keynes

 

[fatherpierre]

huh! no way... mines a 200 but the same basic engine, cant be that much in it!

I bought mine from Mercedes Milton Keynes

Maybe the £12 is for the thermo, and the £63 includes the whole housing???

Is it easy to change?

 

[Will]

It's easy if the bolts don't shear when you undo them.

Be careful!

Also, I'm pretty sure the thermostat top housing has been changed now - the original designs are plastic (?) and can become brittle with age.

Now there is a new, revised type made of metal. Not sure if this applies to all of the 102 engines though?

Will

 

[fatherpierre]

I might have a go at it over the weekend.

Thermos are about £6 from GSF by the look of it.

 

[jaymanek]

oh yes, wouldnt bother changing the whole housing... just be careful undoing the bolts... works better when its slightly warm.

 

[fatherpierre]

Cheers for the advice.

I'll have a tentative crack at it this weekend. I take it that it's pretty simple and quick? There's mention of draining fluids in the Hayne's book....... I don't like too technical

 

[jaymanek]

no need to drain.. of course when you undo the casing a bit will spill out but nothing to worry about...

Crack the bolts off slightly when its warm but dont remove the casing until its cooled down otherwise you could get some nasty burns due to the pressure!

I cant remember if there was a gasket between the surfaces, may be an idea to get this too..

 

[fatherpierre]

I think there was an O ring that you need to replace.

Thanks again for the advice.

 

[vijilants]

Careful when you retighten the the bolts / nuts after you replace the thermostat. It is very easy to overtighten it and when that happens, the threads will strip and then you have another problem on your hands.

 

[grober]

If that doesn't do it, some aluminium foil strategically placed to blank off a small section of lower radiator may help on very cold days but keep a watchful eye on the temperature gauge!

 

[fatherpierre]

If that doesn't do it then I'll wrap up warmer I think!

 

[stever]

I had exactly the same problem on my 230E, and changing the thermostat solved it. Be aware that the ECP doesn't look to be as well made as the MB one - given the low cost, probably best to get it from the main dealer.

 

[fatherpierre]

Main steeler it is then.

Ta