Radiator flush after flush... the rusty water never stops - Page 2 - PeachParts Mercedes-Benz Forum

Mxfrank · #16 11-02-2014, 07:15 AM

Actually, I just didn't think this through. But it's nice to know there are some chemists out there. If the water was ultra pure, it would be pretty stable. What usually causes corrosion is dissolved oxygen.

But the main thought still holds...the problem is the amount of flushing, not whether the water is pure or tap.

leathermang · #17 11-02-2014, 07:25 AM

The problem is the lack of FLOW in the flushing process.... due to the small exit venues usually available... hence my recommendation to take out the freeze plugs and use a directed nozzle on a flexible hose to get down to the bottom of the coolant cavity...and a vacuum inserted will help with muck too heavy to bring to the freeze plug holes .
If you have something like a concrete vibrator with a flexible enough end.... ideal for loosening that built up and concreted sediment.

If someone wants LOW Oxygen water... collect the house AC drip.... also a good reason NOT to use that to water plants... the opposite of hydroponics... which adds oxygen like an aquarium pump does for fish survival...

VT220D · #18 11-02-2014, 08:21 PM

Quote:

Originally Posted by leathermang

The problem is the lack of FLOW in the flushing process.... due to the small exit venues usually available... hence my recommendation to take out the freeze plugs and use a directed nozzle on a flexible hose to get down to the bottom of the coolant cavity...and a vacuum inserted will help with muck too heavy to bring to the freeze plug holes .

I agree. This engine has a serious flow problem.

In my experience keeping a stock W115 at operating temperature is impossible. Every one I've had will hit operating temperature (175) and sink down to about 160. If I open the heater valves it will momentarily drop to 125. I tried numerous new and used thermostats with the same results. Once the thermostat opens during warm up it immediately closes again as a surge of cooled water passes through. However it doesn't close as tightly and 160 degrees is where it ends up. This is all verified with a Fluke non contact thermometer. The gauge is dead on.

This drove me nuts on two cars and three engines until I finally did what the factory did with the W123 and converted to a three stage thermostat and housing. Now I hit 175 and hold it - just like my W123. In my current W115 the only way I can go over thermostatic is 75 mph fully loaded uphill in hot weather. Under those conditions I might hit approximately 195 for a short while but it comes back down immediately. In addition to all this I have a deliberately under driven water pump and a 5 speed which further slows the pump. Now I have good heat and less smoke.

I only mention all this because a hot running W115 is completely outside my experience. I suspect you have a serious blockage in the engine or radiator. A cool running engine in this chassis is the norm. I wish I had a magic solution for you but I think opening everything you can and manually removing sludge is your only course of action. If you have access to an IR thermometer you could check your gauge calibration and sweep the engine for hot spots. That could tell you where the problem is. If you're worried about heater core damage from further flushing just bypass it. Either way I would keep after it. The blocked parts of your engine are well above the average temperature of the coolant.

dieselbenz1 · #19 11-02-2014, 10:24 PM

I have run 1 pound of citric acid in the cooling system heater fully on for 60 miles or 100km which maybe over several days and after a hose flush followed by 3 distilled water flushes I could not detect any further rust. This however were on 617 and 602 engines which both tended to get on the hot side but that treatment curred both engines. Perhaps your treatment using citric acid wasn't adequate just bringing it up to temp before flushing?

Junkman · #20 11-03-2014, 10:58 AM

Are you catching the run off?

Redneck method would be to drain coolant, remove the thermostat, replace tstat housing, fill radiator through the disconnected upper radiator hose, Have another hose to direct water coming from engine, start cold engine and run it until the escaping water looked clean while continuously filling radiator with a hose. Drain, reinstall thermostat, add Zerex to 50% of system capacity, top up with water of your choice, drink a beer.

Diesel911 · #21 11-03-2014, 12:15 PM

I am going to offer a different comment. When I was a Kid and Teen in Californa People used only Water in their Coolent System unless they were going up to the Moutains; someplace where they expected it to get below Freezing.

They also did not do perodic Flushes on their Coolant Systems so scaly Rust would build up inside of those Coolant Systems.

If the Engine already is full of Scaly Rust flushing the Coolant System only loosens it and you can keep getting loose particles of rust for years afterwards.

It was not until the 1970s that using Coolant instead of only Water took hold.

So if your Block is rusted that Rust is going to continue to come out of it for a long long time.
With a Engine in that Condition it is OK to Pull the Radiator and have that tanked to clean it and OK to flush it with Water but you don't want to put anything in it that is going to loosen the rust.

If perodic flushes had been done that that might have prevented heavy Rust build up but if Water had been used as the only Coolant it is going to be rusty in the Block.

Zulfiqar · #22 11-03-2014, 01:28 PM

you are never going to get this clean with the gravity drain method, what you need is to first remove the thermostat, and collect some bits and assortments from an auto parts store.

like a spare heater hose the prestone flush adapters that can accept a garden hose - remove a heater line and install your spare heater hose and cut it to install the adapter you bought, connect your hose to the hot side water line (washing machine line) and make sure hot water is flowing through. Open up the drains on the radiator and block

start the engine and flush it out till all you see coming out is clean water. You need a positive force behind the flush to get rid of this rusty water. Dont worry about the tiny amount of impurities in the tap water (unless you use well water) - if you are very strict on it you can blow air through the system to fully remove all water. Fill as you like.

vstech · #23 11-03-2014, 02:22 PM

At radiator shops they have a hose connector with an air fitting to massively bubble feed the block...amazing what comes out with bubble activated water

Shortsguy1 · #24 11-03-2014, 03:28 PM

Thanks everyone for the new suggestions and replies. So a few followups/replies:

1) The temperature at low or moderate loads is super stable, as it is well controlled by the thermostat. I don't see the wide swings that were described above. Only at high load is the cooling system not able to keep up
2) The earliest 220Ds did not have oil coolers. So the cooling load on my engine is greater than on later engines. This suggests that MB identified a cooling deficiency and addressed it with oil cooling.
3) The W115 FSM says "when driving under load, in the mountains and bumper to bumper traffic...the coolant temperature readout may rise to the red mark (just below 250F) without any fault on the engine." They even bolded the statement "without any fault on the engine." So just because my engine gets very hot does not indicate it is out of the realm of normalcy for w115s.
4) The W115 FSM also provides recipes for coolant/water mixtures and one of the options is ~35% antifreeze. Although all of their mixtures include an additional "anticorrosion oil"... whatever that is.
5) I don't think my engine has the normal freeze plugs of other later engines. All of the ports on the sides of the engine have 17 mm allen fittings in them. None of them are simply plugs like I think you see in the om617.

I decided to roll the dice and do a second full treatment (degrease, citric acid, rinse, rinse, rinse...). This time, I am putting it all through the heater core as well (keeping my fingers crossed). I just started that today so it will be a few days before I know the outcome. As an aside, I do use a hose to push water fast through the heater core and block. As mentioned, the flow under gravity is too slow to carry much sediment. I will post again in a few days with another photo of the rinse water and see if any progress was made.

Thanks again!

dieselbenz1 · #25 11-03-2014, 04:25 PM

When I flush with a hose I supply through a heater hose and plug the other end of the heater hose then watch as it comes out the top of the radiator whith the cap removed. I also pull the thermostat with all other points of exit blocked and watch it come out the block. This way you are certain of obtaining a good back wash. Pull as many hoses you wish one at a time and be careful you do not over pressurize the cooling system as you change flow directions.

Knuckleballerr · #26 11-05-2014, 01:57 AM

Quote:

Originally Posted by mannys9130

Mxfrank IS correct.

Distilled/RO water is very pure. Like, VERY pure. It tends to pull minerals out more readily than tap water (already loaded with minerals). Water is a very good polar solvent. It's not corrosive like Sodium Hydroxide, but it is corrosive in the literal sense of the word.

Engineer here. This is indeed true. I'd like to add pure water is indeed less corrosive than water with impurities; however the effect is still measurable and it can actually attack nearly anything; especially at high temps and pressures. I like to think of it as having an abrasive force rather than an corrosive force, causing the water to retain impurities as a result of this. So using distilled water has no major advantage.

Junkman · #27 11-05-2014, 01:16 PM

On a tangent:

Instructions that came with a new heater core for a Ford truck said to put a volt meter probe into the coolant and ground the other probe. Any measured voltage above .3 volts indicates electrolysis and the need to replace coolant.

leathermang · #28 11-05-2014, 01:28 PM

Quote:

Originally Posted by Junkman

On a tangent:

Instructions that came with a new heater core for a Ford truck said to put a volt meter probe into the coolant and ground the other probe. Any measured voltage above .3 volts indicates electrolysis and the need to replace coolant.

In post 13 when I said ' with regards to that situation can be checked by using an ohm meter... " that is what I was referring to.... which is from the Mercedes FSM....