Re: Coolant Loss - 1989 735i (archive)

Remove the dipstick and examine the oil. If the oil is milky, there is coolant in the oil. If the oil looks right, don't worry. Also, look at the color of the coolant and check that there is no oil in it.

Check the left-hand side of the radiator. Sometimes, the radiator can develop small cracks at the top or even where the plastic tank attaches to the aluminum core. Also check where the transmission cooling lines screw into the tank.

Look at the underside of the water pump with a "mirror-on-a-stick". Failing water pumps leak coolant on the underside of the water pump housing.

Sprinkle baby powder or flour on the radiator hoses then take the car for a drive. Look at the hoses afterwards to see if there are any wet spots. Often, pin-hole leaks do not show up when the engine is not running.

There is an engine block drain plug on the lower right side (passenger side) of the block. The plug is supposed to have an aluminum crush washer. Mine didn't and coolant leaked from the drain plug. It took me weeks to find this one as the hot block evaporates the coolant so there were no puddles on the ground.

Let us know what you find.

Regards

Alex Lynch
1992 735i
1972 2002

I have to add about one quart of coolant every 300 to 400 miles. I have let the car idle for extended periods, no visable leaks. The is no vapor from the exhaust or anti-freeze smell. No wet carpets or any stray collant any where I can see. Should I pull spark plugs? What evidence of coolant burning would I see? Other ideas? The car has 183K miles. Thanks, Dave Johnson

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