C230 coolant change facts and comments

[mpolli]

I could not find any specific info on this procedure for this car so I will post from my experience and anyone else can add comments if they wish. This procedure is for the 1998. I assume it is the same for 1999 also. Any other years I don't know for sure.

There are 2 drain locations: Radiator and block. The radiator drain is on the drivers side (US) of the car at the bottom of the radiator. There is a little nozzle where you can attach a 3/8" or 7/16" ID rubber/vinyl tube. 6" length is good if you are going to catch the liquid in a plastic milk jug (1 gal). There is a little red knob to open the valve and it uses a large blade screwdriver. You need to remove the engine under cover to get to this. The engine under cover is held with 4 screws. I used a 5/16" nutdriver for these but they are technically 8 mm.

I was able to drain 1 gallon of coolant from that drain location.

The second drain is the block drain. It also has a little nozzle on it but it takes a 1/2" tube. You will want that one longer, about 14" probably. That one loosens with a deep 19 mm socket or a 3/4" works good also. It is located exactly where you cannot reach it from top or from underneath and definitely not if the exhaust manifold is hot! It is located beneath the exhaust manifold between #3 and #4 cylinders. I was able to drain 1/2 gal from there. If anyone knows an easy way to get to that drain let me know!

That left 1 gallon still in the system. So I had to puzzle on how to get that out. I thought about maybe running the "rest" circ motor but could not get the connector off. I thought about maybe disconnecting other hoses. Finally I added a gallon of distilled water and ran the engine for a minute and then drained that out. It came out the same color as the other coolant, so I figured no matter how much water I added I would still have some old coolant in there. So I figured I had to choose between flushing it with the hose and leaving some tap water in there, or not flushing it and leaving some old coolant in there. I went with option "A". I put the hose in the filler hole and turned it on just as much as could drain out of the radiator drain. Then I ran the car with the drain open. I should add that I had removed the thermostat for this procedure as recommended by Haynes (put the housing back on with the thermostat removed). The water eventually ran clear, then the temp went up and then the water ran darker again. Keep in mind the thermostat was out so I don't have an explanation for this. Anyway, after a while I decided all the old coolant was out. So then I turned off the car and removed the garden hose.

Then I opened the block drain again, drained everything out then closed both drains and installed my new thermostat. Then I added a gallon of G-05 and 1/2 gal of distilled water. I drove around the block and the add coolant light came on so I added about a quart more. Thats it!