I am planning to drain and flush the coolant on my 99 ML 430. I believe this is recommended every 3 years.

Are there any drain plugs and vents on the engine block that I should look for? I've done this before on my 300E and there is or are vent plugs for draining the coolant and bleeding the air out, as well as topping off the engine block with coolant. I will also be replacing the thermostat (integrated with the housing) and radiator hoses with this task. I would appreciate additional suggestions and comments. THANK YOU.

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Josemin


88 MB 300E
88 MB 560SEL
99 MB ML 430

The block drain I use is on the right side of the block, you can get to it easiest by removing the right front wheel, then use a long extension right on top of the frame rail. The drain is just loosened, you don't need to completely remove it.
There is a drain on the radiator, it's harder to get to than the block drain, hard to get anything on it to loosen it, even harder if there is a brush guard. But I always use it, it's the lowest spot on the radiator. The drain is on the right (passengers) side side tank down on the bottom, facing the front of the truck, not towards the rear. Just inside the front bumper skin.
Gilly

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Thanks again, Gilly. Appreciate the info.

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Josemin


88 MB 300E
88 MB 560SEL
99 MB ML 430

I should have also mentioned that you use an allen socket to loosen it, the tip of the allen socket goes into the hex shaped hole that the coolant drains out of, so just loosen the drain a turn or two, then remove the socket and the coolant will come out.
If you wait long enough with the refill procedure, no special "burping" procedure will be required, the air comes out pretty well all by itself. Hardest part is draining the radiator, have to work pretty hard at that radiator drain. Requires 1/4-1/2 turn counter-clockwise, then the part you are turning needs to be pulled forward out of the radiator to drain, it takes awhile to all drain out, not the best idea or location.

Gilly

ps I think it's a 6mm allen on the block drain. I tried doing the left drain block after draining it all out of the right side, I had no extra coolant come out the left side. Left side seems harder to get at, had to remove a heat shield or something.

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You're right, I looked at the drain plug in the block, it is manageable to get to it. On the other hand, the drain plug on the radiator is hard to get to.

Is there also another vent on top of the block to get the trapped air out, that also serve as the fill hole to top off the coolant?

Once I open and take out the the thermostat and housing, the air goes inside the block, isn't? Or is it possible to 'bleed' the air out by starting the engine and let the coolant fill in the block cavities then top off the radiator with coolant.

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Josemin


88 MB 300E
88 MB 560SEL
99 MB ML 430

Nope, no hole or bleeder screw for air, just leave the cap off the coolant tank. If you wait awhile, maybe a half hour, it will burp very little if any.
Gilly

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