Not So Cool Running  (Chet Hwilka 8/10/07)

For about the past year I've noticed my temp gauge running a little warm.  Typically, about any time of the year the operating temperature would run just over 80C (actually the needle would cover the top of the eight).  Now running down the interstate, the gauge would stay well above the line above 80C.  And if I had to stop in traffic for any period of time, it would creep up over 100C and not want to come down once I got rolling again.  One trip last summer I actually had to turn the heater on to help cool it down.
I had changed the thermostat a little while ago and I keep a 60/40 mix of MB Coolant.  
I figured since the temp did not go down even when I was cruising down the interstate and plenty of air was passing through the radiator, the fan clutch was OK.  It must be a clogged radiator.  So I bit the bullet and bought a new new from MB.  

I was a bit shocked when I pulled the old radiator out and looked inside to find it as clean as the new one.  I figured, well there's $350 down the tubes..

Old Radiator's inside

But, I put everything back together with the new radiator and took it up the road.  Temp appeared to run cooler, but it wasn't particularly hot out, so I still was convinced that that was it...
Well, this past week (8/6/07) here in New Jersey it's been very hot and the other day it hit 99F and the temp gauge never left the 80C mark just like the old days...  Even sitting in traffic the never got close to the mark above 80C...

It's amazing, how a radiator could look so clean and not perform as it was designed...

Disclaimer

The following procedure was done on my 1989 560 SEC and I can't say if this procedure will apply to other years and/or models.  This procedure worked for me and anyone else should use this writeup only as a reference.  
 

Procedure (Refer to Job# 20-420)

Replacing a radiator is a very simple process.  The worst part is dealing with the coolant and AT Fluid.  Simply drain the radiator by removing the plug, remove the upper/lower coolant hoses, remove the AT cooler hose (keeping them away from any dirt), removing the clips and sliding the radiator up and out.
Before installing the new radiator, use a shop vac to clean any dirt/debris from the A/C condenser.  Slide the new radiator in, making sure it seats properly, install the clips, make sure the shroud is centered properly, clip that in and reconnect all the hoses.   Fill with the same amount of coolant you took out and test it out, making sure there are not leaks.  Also don't forget to top off your AT fluid.
Note:  Inspected hoses and belts closely, if they look worn, replace them now while you have easy access to them.  Also examine the AT coolant hose before you removed them and replace if they appear to to be wet around the connections .

That's it..