[W126 Coupe] [W126 coupe] Engine Cooling System

[Dick Spellman]

Hi Yousef:

The radiators develop blockage in sections as they age, you can't 
overcome the lack of cooling in a partially fouled radiator.  Best just 
to replace it if its at end-of life (aprox. 10 years).
Replace the thermostat with the correct rating (not a cooler one) to 
avoid running in a rich fuel condition.  MB thermostat should be 83C not 
75C.  The engine needs to be at proper operating temp (83C).  When you 
replace the thermostat be sure the vent hole is at the high side of the 
motor that will allow any trapped air to escape and this is the correct 
position (orientation) required by MB.   Use only an MB tstat.
Rebuild or replace the visco fan clutch if it is not holding to 3500rpm 
as it should.
Make certain the electric fans function.  Test the fans, relays and temp 
sensors that kick them on.
That should do it.

-\Dick

  On 3/30/2011 6:39 AM, usef nazzal wrote:

> Hey All

> In previous mails Ive mentioned the topic regarding engine cooling 

> along with other topics. However, I would like to focus on Engine 

> cooling this time. I live in a country in which temperatures can reach 

> highs of 113F (most of the year) and lows of 59F (extreme cases 41F).. 

> I have recently bought a Euro 560SEC and i am in the process of 

> adjusting its cooling system in order to accomodate with the extremely 

> hot wether.

> my plan is as follows

> 1) change the Temperature Switch to a lower rating 80-85 C

> 2) Coolant: i know the recommended is 50\50 mix. However, ive heard of 

> owners changing to 60\40 and even 70\30 (Distilled\MB Coolant) plus 

> Water Wetter. I was thinking of going with 70\30 since am gonna need 

> more cooling than anti-freeze. Is this a good idea in my case? I know 

> that coolant increases the boiling point and has anti corroding 

> properties.

> 3) Thermostat: Mister McGoo (Bellamy) suggested replacing the 

> thermostat to a new one.. However i have a friend with some experience 

> with 560s suggested not to do so if its working fine  because 

> everytime he'd replace a thermostat on his 560s he'd end up with the 

> engine overheating.. so i am having my doubts.. Also when buying 

> thermostats, are they available at different ratings? and what would 

> those ratings be? which one would be best for my case?

> probably the answer to those questions would be to try it out and 

> see.. but i wouldnt wanna get in to more complex issues especially 

> with (3). Appreciate your help and suggestions.

> Regards

> Yousef

>

> -- 

> ---------------------------

> Yousef Nazzal