735 freeze plug replacement

i have a coolent leak on the engine back passenger side suspect freez plug but cant see. How big of i job is it to replace? does the motor have to come out??

The 735 has an M30 engine and the block drain plug is located on the exhaust side under cylinder #6. You can visually inspect it for leaks from underneath. There's also a jumble of coolant hoses between the engine and the firewall on the (U.S.) driver's side. Remove the expansion tank to get at them.

If it's leaking buy a new one from the dealer. The procedure would be:
- Drain coolant from radiator into 3-gallon container.
- Drain coolant from block drain into 3-gallon container.
- Replace block drain with the new one.
- Replace radiator drain.
- Set heater controls to full warm.
- Fill slowly to allow air to escape.
- BLEED SYSTEM as follows:
- Add coolant to the expansion tank up to the COLD mark.
- Loosen bleeder screw on thermostat housing.
- Add coolant to expansion tank until it spills from bleeder screw.
- Tighten screw.
- After engine has cooled, recheck coolant level and add coolant if necessary.

Your '88 E32 doesn't have a rear cyl. head heater hose connection like the earlier cars, unfortunately the most likely cause for a leak, from there, on these, is the head gasket..........they'll also leak just ahead of cyl. #1.