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Old 12-02-2002, 12:22 PM
Posts: n/a
Question Liquivac to change coolant?

I recently purchased a Liquivac (like a Topsider) so that I could do oil changes from above. I have a 1991 560 SEC that also needs a coolant change--the PO used the deadly green stuff.

Is there any way to drain the engine block from above with the Liquivac? I really want to avoid all the dripping and splashing that comes along with using the drain plugs.


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Old 12-02-2002, 12:44 PM
Ali Al-Chalabi's Avatar
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Join Date: Nov 2000
Location: Knoxville, TN
Posts: 1,837
Use the drain plugs for the coolant. There is one at the bottom of the radiator and one on the engine block.
Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record
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Old 12-02-2002, 01:08 PM
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Thanks, but I was looking to avoid using the plugs. That's why I asked about access from above.

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Old 12-02-2002, 01:41 PM
Mike Murrell's Avatar
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Join Date: Feb 2000
Posts: 2,574

As Ali pointed out, you have coolant in a number of distinct places.

A suction device might draw coolant from the radiator, but there would be no way for it to also pull from the engine and heater core.

You might try evacuating the radiator which is the messiest part of the project using your suction device(or some variation of it). The engine drain plug in many cases is easily accessible and no where near as messy to deal with. You open the plug and then quickly attach a length of hose that points downward into a pan that's been placed underneath the vehicle.

In the early fifties, there's was a commercial gadget that garage owners could use to remove coolant, but it only removed coolant from the radiator. While I do not condone it, even today you find alot of service facilities that only drain the radiator and not the overflow tank and engine block.
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
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Old 12-02-2002, 02:12 PM
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Even if the liquivac could empty the system, it is not like draining the oil. The system needs to be thoroughly flushed or it's like washing your feet, then putting on dirty socks.

Luckily on these cars, it is very easy to thoroughly flush everything. Remove the hose at the rear, drivers side of the head and the hose from the aux pump to flush the heater core. Open the drain plug at the rear of the engine below the exhaust manifold and then flush through the rear of the head to the drain plug. This is after draining the coolant via the drain cock in the block and the drain cock at the bottom right (passenger) side of the radiator.

Finish flushing by connecting a hose over the block drain and flush through to the drain cock on the radiator.

A thorough flushing and fresh antifreeze is very necessary on aluminum head cars. Mine was not done by the previous owner and the head corroded through. Luckily, my machinist welded it up for me.

Good luck,
Flush that coolant and change it often,
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Old 12-02-2002, 06:21 PM
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Thanks for the ideas. I understand the need to drain the block, radiator, and heater core. And I also understand the need to flush out the entire cooling system once the coolant is drained. But what do you guys do with the "flush water"? I can't very well just let it drain into the street, because our storm drainage goes directly into a local stream. That's the whole issue that got me thinking about the Liquivac. I thought that I could do repeated empty-fill cycles and dispose of the waste water properly, keeping it contained. This was assuming that I could gain access to the basal recesses of the block. I know that the radiator should be no problemo.

Still, it is interesting to see how other folks do their coolant changes.

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Old 12-02-2002, 08:59 PM
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Join Date: Sep 2002
Location: Kingsport, TN
Posts: 375
I admit that I was too scared to open some plugs at the engine, not knowing which one was the correct one on each side.
So I drained the radiator on the passenger side, which is very easy with gloves on and a quarter. The drain plug is actually staying in the radiator and you don't need to hold it or fish it out of the container. I used a large plastic pan to catch the roughly 7 liters of the 12.5 liter total of a 420 and disposed of it in the toilet. Press the hoses to get out more liquid.
Then I refilled with hot water and let the engine run until the thermostat opened. I also had the heat on so the heater core would get circulated through.
I did it a few times and then did the citric acid flush (15 minutes of 2500 engine rpms.)
Afterwards flushing with hot water again a few times (like 6 or 7 times. I calculated that I had the flush reduced to under 1 % of the volume). Then I filled it with MB antifreeze to get a 40% mix.
Yes, it took about 3 hours and my neighbors were wondering what I was doing...
Car runs at 86 to 92 now.
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Old 12-03-2002, 07:00 AM
Posts: n/a
Use drain pans to catch the coolant by placing them under the block drain plug and the radiator drain plug. Pour that into your old anti freeze jugs, milk jugs or whatever you can find and take it to the automotive department of your local Wal Mart for recovering.

The water that you use to flush the system, that drains down the driveway, will have only a miniscule amount of residual coolant.

If you are hung up on environmental extremism, then refill with the MB, non Ethylene Glycol coolant.

Good luck,
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Old 12-03-2002, 09:33 AM
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Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,316
Maybe I'm getting soft in my old age, but this is one job I would give to a dealer or a good independent shop. Makes sense when you consider the environmental issues of disposal, the relatively low cost of having it done and that wonderful feeling of coolant running down your arm.

My $.02.
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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Old 12-03-2002, 12:19 PM
Joseph_H's Avatar
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Join Date: Nov 2002
Location: Texas
Posts: 231
Your Recommendation

Do you know of an excellent independent MB shop in the Houston area (preferably North or NW of town)??
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Old 12-03-2002, 05:09 PM
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Yes. I use Bertini's. They are located on I-45 near The Woodlands. See my post under "Good MB Shops".

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