coolant flush question

[noel.brownell]

I have a 72 4.5 and I am trying to flush the system. I pulled the thermostat and ran a hose into the same compartment and the water from the hose did not go through the motor, it just came straight out of the top of the housing that leads to the hose connecting to the top of the radiator. Any help on how to flush this system would be greatly appreciated.

[bill4247]

Well since you have the thermostat out you could take off the top large radiator hose run it to a bucket open the rad cap put a garden hose in and run the engine. The water should go thru the engine. If the thermostat was in you would have to use hot water to open it. I think above 100 F.

[MAF]

Go to the auto parts store, or I believe even the discount stores, and get a Prestone flush and Fill kit,(4.00).
You install a garden hose fitting in your heater hose,which remains on the car, and is capped up,(supplied in the kit).
Then you attach a garden hose/backflow preventer (all in the kit).attach your garden hose, and start the car, and run the hose/car until the deflector,(in the kit) runs clear water.You will literally see that clean water runs out.
You do all this with the radiator drain valve open, let all the water run out, close the radiator drain and add coolant until the garden hose connection shows the coolant running out.Put the cap back, on the fitting,and put on the radiator cap.
You have a clean radiator, block, heater core,and a 50% dilution of coolant.
I usually run a good flush treatment, for a day or two before I do the flush.This loosens all the crud, and cleans the surfaces inside.
If you want to be more Eco friendly,before you flush,drain the old coolant/flush into a tub,(I use one of those black plastic oil drain pans), and pour it into your toilet.The sewage treatment plants are set up to remove the ethelyne glycol, and this is a perfectly acceptable disposal method.Some auto parts stores accept used coolant too.
Not saying you need to use Prestone, when you finish the flush,you only have clean water, so use whatever you wish for the anti freeze.
I prefer to use Benz coolant,from the dealer.

[noel.brownell]

Thanks The radiator was just rotted out, and cleaned so I was worried that if I ran the car I could get a bunch of gunk in the radiator from the motor. I will flush with kit.

[meltedpanda]

take all the hoses off and run fluid in the radiator to flush then do likewise with the engine, I used compressed air to help the process
read this
Block plugs stuck, ideas for a good flush 450SL

[mercmad6.3]

Removing the thermostat does what you describe.the water no longer goes through the engine,just into the top of the water neck and back out.

Rather than buy stuff from a parts store,go to a merc dealer and buy 1 liter of their citrus flush. Replace the thermo or fabricate a disc that will allow the water to circulate through the block and again and use the flush as per instructions. There is a proper tool for this,the part number escapes me...Plus mercedes headgaskets don't like the acidic qualities of a lot of the flush products out there which is why I only use the mercedes product. Normally,the top hose is replaced with special hose that has a water connection. you run the car then turn on the connection,this replaces the citrus /dirt mix in the radiator while you idle it. The water circulates fully cleaning it properly.