Re: Least Invasive Engine Coolant Change, 750iL (archive)

I'm trying to drain my cooling system. The Bentley manual says that the engine block drain plugs are below the no. 4 and 10 cyl. exhaust ports. But I still couldn't find them. I also searched the archives and couldn't find anything. Can anyone please help? Thanks.
Mark d
1990 750iL

Required Materials:
10 gallons distilled water
2 gallons of Prestone (or equivalent)
1 lower radiator hose and worm clamps
1 large pan to catch coolant
20 gallons of empty containers

1. To drain half of the coolant in the cooling system, remove the lower radiator hose. Don't try to save the hose. After removing the worm clamps I cut a few longitudinal slices at the ends of the hose so you can peel it off and not risk breaking the plastic fitting on the radiator. Put on the new hose and fill the system with distilled water.

Your system should be self bleeding. To make sure it is, see if you have a small tube coming off the top of the radiator on the drivers side that tees into another one coming off a housing on the block behind the radiator fan. This tube leads back to the radiator cap to automatically bleed the system.

Start the car and turn the heat on full hot. Wait for the upper hose to get hot. Stop the car and remove the lower hose radiator hose. Do this until the water coming out of the lower hose is clear. After draining the last time, (you may need a helper for this) leave the lower hose disconnected from the radiator. Begin filling the coolant reservoir with full strength prestone. You will notice clear water draining from the lower hose. When this turns green, connect the hose to the radiator and continue filling.

Good luck,

Scott

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