W140 S320 Overheating help!

Ventolin

New Member
Joined
May 20, 2007
Messages
27
Car
W222 S500, W140 S320
Hi,

My S320 W140 started overheating one day - heard knocking sounds then bubbling / gurgling and noticed the temp had shot up to 120C. Pulled over and turned the engine off and let it cool down. Couldn't drive it for more than 3 minutes after that having to pull over and let the engine cool down for 10 minutes before making another 3 minute journey.

After some searching found that I should put the heating on full blast and that will help cool the engine.

Tested this today and sure enough was able to run the engine for about half an hour with the heater on full while idling.

I also thought there might be air bubbles so ran without the radiator cap on and squeezed the hoses to try and push any air out. All 3 visible big hoses were getting hot.

When I turned the heating off however, the temperature shot up after a couple of minutes until I turned the heating back on again.

The 2 auxillary fans at the front come on around 90C but even with these on the temp still shoots up.

There doesn't seem to be a water leak although I did top up the expansion tank with water on the day it happened (a few weeks ago) and topped it up a little today.

Can anyone please give me any suggestions as what to it might be? Trapped Air? Thermostat? Radiator clogged up? Water Pump? What should I check next?

I would love to take it down to PCS and have Olly and his team look after it, but I don't know if I will be able to drive the car all the way there given that I'm in SE London. Would it be possible with the heater on full blast?

Perhaps someone has a recommendation for a good indy in SE London that I might be able to drive to?

Thank you for any help in advance!

Vent
 

renault12ts

MB Club Veteran
Joined
Mar 5, 2009
Messages
16,163
Car
2005 W215 CL500.
The vanes of your water pump may be broken off.
 
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Ventolin

New Member
Joined
May 20, 2007
Messages
27
Car
W222 S500, W140 S320
Thanks guys, I will try replacing the thermostat first before investigating the water pump.

Are there any recommended parts sellers here I should get one from? I'd rather buy a genuine / equivalent from here than from Eurocarparts / GSF.

Best Regards,

Vent
 
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Ventolin

New Member
Joined
May 20, 2007
Messages
27
Car
W222 S500, W140 S320
Bought the Thermostat from Mercedes - £30...

Took the old one out and the rubber ring had disintegrated. Cleaned up the housing and put the new thermostat in. Took 2 hours in total, most of which was cleaning.

Car now reaches around 83C and stays there. Great!

Thanks for the help guys!

Best Regards,

Vent
 

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