Flushing coolant on M60

[Alpinewhite]

Hi,

Do the drain plugs have any O-rings? How to make sure they will not leak after I done flushing. Should I buy some new fastners, O-rings, etc., for this job?

How long should I wait for the car to cool down before I start the job?

Thanks
Arun

[joshua43214]

The block drains have copper or aluminum sealing rings, its a good idea to replace them. the radiator drain has a built it seal and is re-usable. make sure the car is flat on the ground when you drain it, so raise it off the stands and set it on the ground for a few minutes. If the car has been properly maintained all you need to do is drain and fill, the residual amount of coolant left in the heater is fine. I have actualy known techs to save old coolant on well maintained cars to top up coolant on other cars during oil service. If the coolant is discolored, flush it with clean water, heater core and all.

If you flush the system, add 1/2 of cooling system capacity of pure coolant, then add water, this way you wont end up with weak coolant from adding50/50 mix to water.
If you don't flush, fill with 50/50
If the block doesnt't drain, poke a pocket screwdriver into the drain hole, its probably blocked with detritus, this is not abnormal.
My method for filling BMW's may be a bit different than others, remove the upper hose (left side hose) and stick it on the radiator, fill the radiator, then remove and stick in on the engine and fill the block, now put the hose back on as intended. this will ensure the cooling system has enough coolant to bathe the T-stat and eliminate the biggest air pockets.
The radiator drain is very very low torque, it takes very little torque to make the treads catch enough so it won't unscrew.
I always test drive a vehicle before I service it, so I flush them at operating temp, but for safety you should wait until you can lay your hand on the side of the engine block comfortably.
The proper amount of coolant is in your owners manual, use this information before a non BMW source(reprinted with BMW permission is non BMW).

[Alpinewhite]

My PO has put green stuff in there. That is the reason I want to flush it. I would like to flush the whole stuff and replace it with BMW coolant.

I understand it is not easy to remove the coolant in heater core. Is it OK if the green and blue mix?


make sure the car is flat on the ground when you drain it, so raise it off the stands and set it on the ground for a few minutes.

Does this mean I cant do the whole job by plcing the car in ramp?

Thanks
Arun

[Alpinewhite]

The block drains have copper or aluminum sealing rings, its a good idea to replace them.

what is the part number for these? Will the parts guy understand if I say sealing rings for drain plug?

My car is a 1995 530i

Thanks
Arun

[joshua43214]

The aftermarket parts guys will only be able to match up the old sealing rings. BMW can look it up by description.

Just drive the car off the ramp, let it sit for a moment to drain with engine off, drive it back up. It won't hurt anything to run the car long enough to drive it down with no coolant.

People needlessly complicate flushing heater cores, intruth, if your intention is to remove every trace of the old coolant, the heater is the least of your worries. Follow the three hoses from the heater and undo them, one is a common water source (right side I think) from engine, the other two come from the water valve via the aux water pump. run water at low pressure through the common hose ( loosly clamp a hose with vice grips) and then clamp the other two hoses back and forth until it runs clean. the idea is to bypass the water valve and spray it out as a separate part. you can flush straight through the aux pump.

Do not use the big heavy duty clamps sold at parts stores, they are hell on plastic fittings even when properly torqued. Use BMW clamps or something that is similar, tighten them just enough to make a small impression, run the car till the hoses soften from heat and tighten them a tad more. If you are stripping the threads on a BMW hose clamp, you are using way to much torque.

Flushing back through the cross over pipe behind the heads will get alot of the old stuff from the heads, but the water will the path of least resistance, which is back through the water pump. The only way I know to get it all out for sure is not a safe method for the inexperienced so I won't cover it. Just do the best you can. The slow way is to repeatedly fill the car with clean water and run til hot until it comes out clean. You could pop out the T-stat and attempt to blow water thruogh the pipe and hope it cleans both heads.