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radiator flush

9K views 13 replies 6 participants last post by  nowhereman 
#1 ·
to use or not to use is the question.
i will be changing coolant this weekend. what are members thoughts about using a coolant system cleaner/flush. but then doing a partial drain out ie removing fluid from radiator bottom and thermostat hose. and not opening the engine plugs?
cheers
 
#2 ·
For the most part, No cleaner is necessary. Remember Distilled water.I do four water changes, but let the car warm up, and let it pressurize with the heater at full for each water cycle.

While you add it, change you heater tee(if you have not changed it). Change your thermostat every couple years. Change the radiator petcock valve, and a new coolant recovery tank cap when you are done for sure...While you added, change the skinny tee hose assembly to the coolant recovery tank hose assembly if it has not been changed

Heater tee:

http://www.benzworld.org/forums/w140-s-class/1320788-evil-lurks-under-hood-really-devil.html

Recovery tee:

http://www.benzworld.org/forums/w140-s-class/1719760-another-coolant-fitting-breaks.html

Aftermarket coolant:

Valvoline.com > Products > Zerex > Antifreeze Zerex > Zerex G-05® Antifreeze / Coolant

Best of luck,

MArtin
 
#3 ·
:eek:
had no idea about the Tee
thanks for the link , there are 24+ pages ..
part # is 1408301696

does this problem occur in any particular year?
does the problem occur in a 129 500 , as i have no heard about this problem on that forum..

really appreciate that you bought this issue up..
will be replacing asap..
 
#4 ·
The tee is a killer on these late W140s. The only symptom is the low coolant light, and in matter of a minute on the highway your engine is toast-cooked!!The early cars have a metal tee.

Buy the tee from the dealer. No ebay or aftermarket here...

Silly me drove with a broken tee for about 1000 mile joy ride...They are good for 70 to 80k miles. Mine broke at 100k miles..

While draining your coolant, Check that your low coolant light works..

Best of luck,

Martin
 
#5 ·
Some people here have offered clean metal tee's for sale, try and get one of those and never worry again. I wish I had known before I sent my early parts cars to the scrapyard, I could have salvaged 2.

While you have the coolant out, I strongly recommend removing and inspecting your duovalve; mine was all gunked up. The heater sort of worked prior to draining but stopped shortly after. I had a nice clean one to replace it with, but could also have cleaned out the original one, I think.

My regime with a new acquisition now is to flush and inspect the system obsessively as I've had a couple of failures in the past that have left me stranded in the boondocks. For the 600SEL I did the following:

- Drained and refilled with tap water, added an acidic flush. (This is a 20 minute product)
- Drained and rinsed 3 times with tap water.
- Refilled with tap water and a long term alkaline flush. Drove it for a couple of weeks.
- Drained and flushed 5 times with distilled water.
- Refilled with 50/50 mix of Zerex-G05 and distilled water.

Also changed the top and bottom radiator hoses, they are cheap and usually need doing. I did that after the acid flush so I could check for leaks before putting the Zerex-G05 in.

Overkill, perhaps, but it's clean as a whistle now.

My low coolant switch was broken, stuck in the on position, but that was the magnet inside the coolant tank so I had to replace that.
 
#6 ·
Just drain the block. It is simple as there is a hex head bolt on each side. If you can't find them, you shouldn't be performing your own maintenance. Yes, distilled water at 50/50 to G05 (hybrid organic) coolant. Half the fluid is in the block. Asinine just to replace radiator capacity fluid only as the block fluid is mixed.
 
#8 ·
The normal service schedule is to drain the radiator and add a 50/50 premixed coolant. This is sufficient if the car has always been serviced on time and the manufacturer recommended coolant used. If you know that to be true, you can continue the practice.

If you are unsure of the vehicle history, (as I was), then the rinse and repeat process removes almost all of whatever is in there for a clean refill.

By this I mean, consider that what is in there initially was 100% crud. My car takes 20l and I can get 10l out via the radiator drain plug. I drain half, fill with clean water and run the car up to temperature with the heater on full for a while to have it circulate thoroughly and then let it cool a bit. That means it's now 50% crud. Next time it goes down to 25%, and by the 5th time it's about 3%, almost nothing. I drain again leaving 10l of nearly pure water and top up with 10l of Zerex-G05, giving me a 50/50 mix.
 
#9 ·
Finding the block drains isn't always the problem. On the S600 it looks suspiciously like the exhaust needs to be removed to get to the drain on the passenger side.

Doesn't anbody else give the system a flush with a hose pipe?

I haven't changed the coolant on my w140 myself (Last change was done by a specialist who also did the water pump) but will do this summer, but on other cars I've used a hose pipe prior to a chemical flush.

Remove top and bottom rad hoses, and insert a hose pipe in the top and let it run freely for 10 mins.

Same with the engine block, remove stat and undo block drains and let a hose pipe run freely for a while.

Finally, same thing with the heater core.

Citric acid is good cleaner if there is any scale/rust build up in the system. 500g of citric acid powder dissolved in hot water added a fresh water coolant fill and run the engine for 20 mins.

If you're trying to remove oil deposits after a head gasket, I've seen mechanics use laundry detergent to good effect. The "Automatic" variety for washing machines is low foaming, and apparently works a treat.

For the m104 MB sell a "Permanently opened thermostat" designed to be fitted for coolant flushing. No idea if something similar is available for the m119 and m120.

If you're using a chemical flush product, it's worth checking the concentration needed. Using the Forte coolant flush for exmaple requires 4 bottles for the correct concentration for the m120s 19L coolant capacity, which can get expensive.
 
#11 ·
I've tried using a hose to pressure flush in the past. Can't do that where I live now and I find my repeated filling method works just as well. The acid flush is for scale, the alkaline flush is for oil and organic contaminants. I've heard of detergent being used but I would never add something like that after an experience with another powder flushing agent that cost me an engine.

Orange coolants are usually OAT (Organic Acid). The MB one is HOAT (Hybrid Organic Acid) and they shouldn't be mixed. My flushing method will get rid of all the old stuff.
 
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