Timm's BMW V8 E31/E32/E38/E39 Successfully filling and bleeding the cooling system in 10 steps

Bleeding the M60, M62 and M62TUB engines seems to cause all sorts of problems - but it shouldn't. The most important thing to bear in mind is that the operating temperature is above the boiling point of the coolant. It only stays a liquid because the system is under pressure - and if you release that pressure (by removing the filler cap) the coolant will boil and force air into the system. This is the main reason for failure to bleed successfully. The system pressure is set by the filler cap - it has a 2-Bar pressure- relief valve built into it. The expansion tank is designed to allow for coolant expansion and an air space for the coolant to expand into. If the system is over-filled, the excess is ejected under the cap. Here's a routine that has always worked for me on the 7 BMW V8's I've owned: Use a 50/50 mix of BMW coolant and ionised (or distilled) water to refill the system. If the cooling system was completely drained, the full 12- litres of coolant will be required. Follow this procedure for re-filling

1. Re-connect the battery if previously disconnected 2. Switch the ignition to position II, do NOT start the engine 3. Set the heater to 32C on both sides, fan at lowest speed (but not OFF) 4. Loosen the bleed-screw two turns 5. Pour the coolant into the expansion tank, if the coolant reaches the neck of the bottle fit the cap and tighten the bleed-screw, squeeze the top hose a few times, remove the cap and loosen the bleed- screw 6. Once you have at least 6 litres in the system, start the engine and position the car facing up an incline (or drive on to a pair of ramps) 7. Stop the engine, then return the ignition to position II, re-fill the expansion tank fully (up to the neck). Squeeze the top hose a few times, at this point the coolant should be circulating via the auxiliary pump and coolant should be seen entering the expansion bottle from the small-bore pipe into the neck of the expansion bottle. If the coolant is not circulating, squeeze the top-hose and while squashed fill the expansion tank right up to the brim, release the top-hose. Repeat until the coolant circulates. 8. Refit the cap, tighten the bleed-screw and start the engine, if the heater matrix has been drained rev the engine to 3000 RPM as this pushes the coolant through - loosen the vent-screw at regular intervals to release any air: 9. Allow the engine to reach operating temperature while ensuring the 'Low coolant' warning does not show on the instrument cluster. Only top up the fluid if the warning is shown, stop the engine when re- filling. 10. Once the engine has reached operating temperature, switch the engine off and check for any leaks. Only attempt to get the coolant level exactly right when the engine is fully cool (at least 8-hours)

If you follow the procedure above there should be no problems with over-heating. Do not attempt to add coolant when the engine is running, it will only introduce more air into the system. The V8's tick-over coolant temperature is 105C - 110C which is over the boiling-point of the coolant, if you leave the expansion cap off while the engine is running the coolant will boil out and you may damage the engine. Only adjust the level when the engine is cold (eight- hours after the engine has been run). Only use BMW anti-freeze at a 50/50 mix. If you cannot manage to bleed the system - read this for repair instructions

Use Silicone Grease to lubricate the bleeding screw o-ring