Joe,
I've been thinking that the A/C condenser sitting in front of the radiator is a problem and that MB did not design the early cooling system with enough overhead to handle the added load of A/C in hot climates - sounds like you've found a solution to this with a 3 row offset core radiator.
Brad,
Understood - hope it was of some assistance - I realize you'd already done the flush, that's not really what I was banging on about - but just a different method when you find some serious junk in the block. You followed the factory procedure and that is exactly how I did my 560, when I replaced the radiator on it back in 2009.
I learned from that time, that one flush was not enough to clean the alloy block, so I did it 3 times. But when it came time to do the SLC, and especially after I had all the strange temp issues, I decided to substitute the radiator, after doing the first flush and then driving around and watching the temp go right up to the 200º mark. So for me, it was a done deal. I wasn't going to waste the extra $ on mb citric acid, and knew I would need bulk amount, so I found a home-bre place nearby and bought 5kg for less than the cost of 500G from MB... heheh
I devised the swirl pot plan and an extended flush, because I had to remove the radiator as part of my diagnostic process. I only made the suggestion here in case someone experiences the same issues in attempting to diagnose their cooling system issues.
Anyway, Like I said, I thought I had the problem licked..... but it turned out that despite all of the rad cleaning (I used progressively more concentrated HCl and ZnCl solutions to try and clean the cores out) and the flow appearing to be absolutely fine, the core itself was 80% blocked - after I cleaned it out.
But the AC condenser is not likely to be contributing much to your problem, unless the cooling fins are caked with junk, causing an almost complete loss of airflow. You can easily clean them though... first remove the aux fan, then you need to spray the core with some heavy duty degreaser and agitate with a brush - like a dustpan brush, following the fins. let it penetrate, and repeat if necessary.
I carefully rinsed mine with a pressure washer - (If doing this you have to be careful, as you can lay the fins over if you hit them at an angle other than straight on) after cleaning with the brush. I already had the radiator out, so it was no big deal. After that I used a compressor to spray air through the core to ensure it was clean. I wouldn't do this procedure with the radiator in though.
Also check a couple of other things. Check the AC pressure switch on the receiver drier, which operates the aux fan is working correctly and also that the temp sender is operating correctly.
That's about all I can think of that could still be contributing to the problem.
The reason I say this, is because my 72SLC was a very early model, with the fluid coupling 4 speed, separate oil cooler and trans cooler in the bottom tank of the 4 row radiator. Prior to observing the rapid change in cooling system performance, the car had done 3 hot summers with very minimal maintenance, giving no trouble.
One thing I will comment on though... is the use of non-genuine coolant.
I'm a bit sceptical about it's use now. I used Zerex G-05 in 3 of my cars, prior to having to completely overhaul cooling systems. The only car I never used it in (the 560SL, Stella) is the only car to never give me trouble with the cooling system. When I purchased that car in 2007, I bought a replacement radiator as it was leaking at the side of the core when I bought the car. I hardly drove it then.. In 2009 citric flushed it, dropped in the new rad, and new hoses. It's been perfectly fine since, only requiring routine maintenance (coolant change and new header tank cap).
Every MB I've used G-05 in, has within several months, required a hefty cooling system overhaul. I'm not implying G-05 is bad - but simply that every system It's been in, has required me to spend a lot more money on, than the car I have used genuine coolant in.
the 16v has caused me the most problems. What is really annoying though, is the fact that until I replaced the coolant with genuine (after the 3rd thermostat housing exploded-) I had problems. Genuine MB coolant was obtained on a saturday (from a damn dealer - $154 for 5 litres... bastards) and it's been a summer, interstate trips and no problems. go figure.... (this is still on my radar...)
The 2.6 had some strange issues with climbing temps. I replaced the thermostat, new header tank and cap and new hoses, did the flush, and it too still had climbing isues in neutral weather. note that the m103's are pretty good when it comes to temp management (201's and 124's are designed pretty well in that regard) but it was not until I changed out the coolant genuine stuff, that the unusual climbing disappeared.
Now this is not anecdotal. I carefully check these things, and I am not sure why the genuine coolant is so much more stable compared to another brand. But when you replace like for like, in a newly overhauled system, and after testing the aftermarket stuff in that system, flushing it and using genuine stuff and seeing the issue go away??? well I'm a sceptical fellow... So I continue to observe.
Bear in mind when I was diagnosing the temp issue in my SLC, I had prior to this, performed the flush, new koblenschmidt water pump, new thermostat & housing, all the hoses, header tank, tank cap, visco fan coupling as well. Tested the senders, tested the gauge... checked everything. Other than a leaking heater core, this was as far as I was prepared to go in my investigation (notwithstanding I did not see any leaking from the trans tunnel, so the core was good in my opinion).
So there you have it. Strange things are afoot at the Circle-K.
I'm still looking for some hard fact that proves what the difference is between MB coolant and G-05. But my hip pocket is saying the cost of the coolant so far, has outweighed the cost of replacing cooling system components in the other cars.
So I'm using genuine coolant. That is the only real difference now.
I can report that when doing the annual fluid flushes, that there is no slime, no white crystals and no discolouration. This is in the m104, the 16v and the 560.
As I no longer have the 201.029 (andrew has that now) and the SLC has gone to live with Craig B, I'm still confident both of those guys are going to have excellent cooling system reliability.
I now do the flush every 2 years on the cars as routine maintenance. Coolant is replaced at 12 month intervals to be on the safe side.
I do not have to remove the radiator... it's just that now I have the swirl pot, I find that is is a good idea to remove the radiator anyway. on the SL it's a 5 minute job. on the 124, it's a 20 minute job. on the 16v flushing the system is a one-day job. (price you pay for owning one).
Maybe I'm a bit OCD when it comes to cooling systems, but I gues anyone else here would be the same if they found out how much it costs in preventative maintenance as opposed to shelling out to replace bits on more than one model mercedes....
aye, there's the rub.