figured I'd post my own, coolant bleeding..

[bimmernut333]

I already posted this but figured I might get a quicker response posting my own thread so here goes... Since we're on the subject it'll be a good time for me to ask. On the Tstat housing where the bleed screw is there is that opening where the coolant comes out. I've debated on welding a nipple or hose barb over that opening so I could use some clear tubing and run it right back to the expansion bottle. My thoughts are I could run it as long as I'd want, be able to visually see there's no more air coming out and wouldn't be losing coolant down the front of my block.. it would rather recycle the coolant back into the system.. any thoughts? Would this work? If so why wouldn't BMW do this from the factory?

[jlevie]

You could do that, but it seems like a lot of work for very little gain. On average the bleed screw is going to be used every other year when the coolant is changed and the total spill from the screw is only going to be a ounce or two. If you are having to use the bleed screw more often, there is some problem that needs to be fixed. And if you are dumping much fluid from the bleed you aren't correctly bleeding the system.

[bimmernut333]

Well the engine that's currently in the car definitely has a leak somewhere in the system. However I have no clue where as there's no dripping or puddles and no mixing with the oil. I've just noticed every couple months or so i'll need to bleed it again. So I'm honesty not too worried about this engine but figured I could do this to my stroker engine while it's still on the stand just to simplify things in the future for me. I figure it would just alleviate and doubt about getting all the air out.

[jlevie]

If you are having to bleed the system periodically there is a small head gasket leak. Once full and bled there is no other way for air to get into the cooling system. A small leak can cause an inexplicable loss of coolant. The leak causes excess pressure in the cooling system and the cap lifts to vent release the pressure. When the cap lifts coolant is dumped overboard. If this happens when driving there will be no evidence of where the coolant went.

This is something that requires immediate attention. The pressure cycles will eventually cause a hose or radiator failure and all of the coolant can be dumped in seconds. Or in a worst case, the heater core could burst and dump hot coolant on your feet.

[5Toes]

E30.de recommends using a a bicycle intertube, cut open and tied on one end. Stretch it over the coolant expansion tank opening and pressurize the cooling system