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Originally Posted by spidertri  You should just save that as a word document Jesse, that way you don't have to retype it every time.  |
Lol, that's a good idea Dave, I think I'll do that
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Originally Posted by tylerwillingham I did actually watch the coolant boil out of the cap. I let the car run at idle for about 5 or more minutes. My fan was coming on without the air conditioning quite often. At least I think my air conditioning has been off. I can't feel anything coming out of the vents. But a previous owner also carelessly put the wrong sticker over my knob to control the speed of the fans. I have red to blue temperature control sticker where my sticker should be for the different types of AC. I'll take a picture later to explain that.
Anyway, yes I saw the coolant overflow from underneath the cap and I am missing a lot of fluid now. My thermostat housing also had a crack in it that I found once my dad and I removed the housing to change the thermostat. I have a new housing on the way from a local BMW dealer that will be here Tuesday (was supposed to come this morning) and the gasket for that housing so I can't really run the car until then.
But once I get that all together, you're saying just try to bleed it? And my puller fan should not actually come on anyway? And, if I got air in my coolant system that could be the result of my coolant boiling out of the reservoir? |
Well technically the fan should come on, but myself and a few others have noted that ours have never kicked on except when the A/C was running. A few people here have had the same problem and IIRC there's a thread discussing a way to rewire the fan so it wil come on. Honestly I think there's a factory flaw in the relay circuit, but the point I was trying to make was that if the rest of the system was working properly ie; water pump & thermostat, the fan shouldn't have to turn on unless you're stuck in traffic on a scorching summer afternoon.
I've heard of radiator caps failing which allows the coolant to expand and boil, but in your case I'm willing to bet it was the cracked thermostat housing or perhaps another leak somewhere which allowed air to collect in the system. If your car is '96 or newer(M44), it should have a plastic housing with an integrated thermostat. It's sold as a complete unit(thermostat+housing). '95's(M42's) came with aluminum housings and the thermostats are sold separately.
I'm the type of person that likes to find the root of the problem and start from there, but sometimes one thing leads you to another and the next thing you know you're on a goose chase, lol. Although I've never used it, you might try a coolant additive by Redline called "water wetter". This might be sort of "band aid" fix, but several people on this forum have recommended it as it's supposed to raise the boiling temperature of the coolant and reduce the surface tension or somehow encourage the air bubbles to escape during the bleeding process.
The bleeding process could be somewhat tricky and usually takes several attempts to relieve all of the air trapped in the system. In your case, bleeding the system is a must, since you're replacing the thermostat. Anytime you open the loop, it's recommended to bleed the system. I even recommend bleeding it if you're just topping the coolant off during a routine inspection.
In extreme cases of air-lock, you'll notice that the heater will not produce hot air. This is due to coolant not being able to circulate through the heater core. Make sure you follow the steps exactly as stated in the link I posted.