overheating problems

[pluggers]

Just of late I have noticed that the engine water temp has been a bit funny.When I am driving along the temp is fine at about 82deg but when I slow down for traffic or join a queue for more than a couple of mins the temp starts to rise fairly quick and after about 5 min its nearly hitting the red and water is been ejected through the radiator cap vent.As soon as i move off into free flow traffic it goes down to normal operating temp (82deg).I have checked the internal heaters and they blow hot air when needed and there is water in the radiator Has anyone got any ideas.cheers

 

[jaymanek]

yeh sounds like you have a blocked radiator.
In traffic, temp will rise a bit, maybe up to 90, but any more and u have something wrong.

Not sure what type of fan you have, could be related to that i guess...

If you do need a radiator, get an MB one, its not much more expensive than from a local motor factor, and they are produced to a higher standard.

 

[pluggers]

I have got one of those viscous fans.Cant really tell if anything is wrong with it unless it isn't spinning fast enough.

Dont know about a blocked radiator im thinking if it was blocked there will be no flow through it, the heaters wouldn't get hot, and the engine would overheat even when driving

 

[andy_k]

our 230TE rises to just over 100 in traffic jams then the fans kick in (actually at 105 C) taking the temp back down to about 90, then the temp seems to cycle around those 2 marks until we get moving again.

That bit is normal according to the manual and Andy Gayle and most Mercs should behave in the same manner.

The fact that yours is blowing water out isn't normal and suggests to me one of a few things that are worth checking.

1, is the cap on the reservoir sealing properly?
2, is there a very slight leak on the reservoir?
3, are any of the hoses leaking?
4, is the coolant mix correct?

The reasons behind these questions is that it sounds as though the coolant in your system is boiling and expanding and being blown out of the system to relieve pressure.

If there's a leak anywhere then the system loses pressure and the coolant will boil at a lower temperature than normal.

So a quick check for even the smallest leak may solve your problem - I'd start with the cap on the reservoir they have a limited lifespan and are prone to failure on any pressurised system also it's the easiest/cheapest option to replace first

There's a very simple way to check your viscous fan is working

use the "carrot test"
Andy

 

[pluggers]

Carrot test. LOL Have i got to dice a carrot in the fan?Ill try it anyway

 

[andy_k]

yep - you get to dice a carrot.

it works a bit like this

1, start the engine and before it gets hot push a carrot into the fan blades - it should stop the blades spinning - withdraw the carrot

2, wait for the temp guage to get up to 105 (the point where the fan coupling engages) and push the carrot back in again (but not too far) - you should get instant diced carrot

3, when the temp of the engine drops again to below 90 try the carrot again - it should once again stop the fan.

Step 2 very graphically illustrates why you use a carrot and not your finger to test the fan.

If the carrot fails to stop the fan when the engine is cold then the coupling is seized and not working properly, if it stops it when the engine is hot - it's not working at all. In both cases you should replace it although the seized coupling is less urgent as the fan is engaged all the time.



Andy

 

[jaymanek]

Hi,

Basically if its a little blocked, you will still get the hot heaters etc, just not enough flow to keep it cool in traffic... Thats what happened with mine anyway.

Viscous fans - Accelerate and the fan should sound like a really deep whoosh....

Carrot test also good!...

 

[pluggers]

Just tryed the carrot trick got the engine up to temp,the carrot lives on so I tried the same thing again but at nearly 120deg and the carrot live's to fight another day or until it get used for dinner.Belive it or not when it was at 120deg the carrot stopped the fan and I was still able to spin the fan in the opposite direction for at least 5 revolutions before it started to turn in the correct direction!!!

Thanx for your input I shall now take the car in tomorrow and have a new unit fitted under warranty(thank god I extended my policy for another year)