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i just replaced my thermo time switch. i didn't drain the coolant, i just plugged the hole with my thumb and then threaded the new thermo time switch in. then i just topped up the coolant in the bottle. i went for a test drive and noticed a higher than normal water temp on the gauge. when i shut her down i saw that coolant was coming from the drain hose that comes of the cap on the top of the over flow bottle.

my question is ( and i probably already know the answer but i thought i'd check with you guys any way) do i need to bleed the cooling system? do y'all think its running hot because i got some air in the system?

I found this somewhere ...some time ago - have not used it yet

There is a sure way to bleed the cooling system on 'big' six engines.
1. After repair is made (before adding coolant) remove bleeder screw and run
a small piece of wire down the hole to dislodge any mineral deposits..
2. Replace the screw, but leave valve 'open'.
3. Open heater control valve and add coolant until it begins to escape from
the bleeder hole.
4. Now close bleeder screw and replace the expansion tank cap and tighten.
5. Remove the small coolant line that runs from the radiator to the
expansion tank AT THE EXPANSION tank and hold it as high as you can.
6. Now attach another hose the expansion tank in place of the one you've
just removed. BLOW (gently!!) through this hose until coolant emerges from
the small elevated radiator hose.
7. Now remove the 'blow' hose and reconnect the small radiator hose to the
expansion tank..
8. Now top off the expansion tank to the full mark

Only dumb if you don't ask and crack the head.

Far as I know, the systems are self bleeding. Within reasonable parameters, or not to be stubbornly confused with pegging the needle waiting for it to happen.

Maybe after it cools back to zero, outside air temp, try again and see where the needle goes. If it still runs higher than where it did before the switch, it's going to be a contest of how much higher, when, maybe another cool down cycle, or doing the bleeding routine.

Besides the coolant puddle ( pet danger, etc.), you can just open the bolt until the flow is free of bubbles. Keep the reserve tank up to proper level in the process. Last stop before coolant flush and fill is jacking the car to make the bleeder the high spot.

You need to bleed after replacing switches. Generally when you replace the switches, you should open the cap on the reservoir and crack the bleeder just a bit.

You have air in the system, which is why you're losing coolant.

thanks for the replies, guys. yeah, its pretty much what i was thinking. now, if i can just get that bleeder screw to budge (its the slotted style) without breaking it. i'm letting it sit overnight after hitting it with some pb blaster. wish me luck.

the good news is that replacing the the thermo time switch appears to have solved my sputtering engine problem.

Well, there's some good news. Now the rest is a simple fix. Good luck!

i'm worried about the condition of the bleeder screw. its in rough shape, looks like its been stuck before. why would BMW spec a slotted screw for this part? seems stupid. i'll hit it with some torch heat before i try to open it.

under the radar wrote:i'm worried about the condition of the bleeder screw. its in rough shape, looks like its been stuck before. why would BMW spec a slotted screw for this part? seems stupid. i'll hit it with some torch heat before i try to open it.

They did a slotted screw, then an internal hex screw, then finally an 8mm hex.

under the radar wrote:i'm worried about the condition of the bleeder screw. its in rough shape, looks like its been stuck before. why would BMW spec a slotted screw for this part? seems stupid. i'll hit it with some torch heat before i try to open it.

PB blaster should do the trick. You can also had heat....as the housing is aluminum and the screw steel. The aluminum will expand faster than the steel and help out.

In the FAQ, there is an article about someone welding that old screw to a rod...but a serious hold with a good set of vice grips should do fine.

Make sure you have the 8mm replacement bleeder BEFORE you remove your old one. Back under my small shadetree. Greg

is the bleeder different than any old 8mm bolt?

under the radar wrote:is the bleeder different than any old 8mm bolt?

Yes....it is.

http://www.rmeuropean.com/Images/produc ... 95124A.jpg

You can also clamp a small vice grips or even just a pair of channellocks on the shaft of the bleeder screw as you're trying to unscrew it. Reinstall with anti seize. The later hex head is undeniably better, but I've never broken or stripped the slotted kind myself, and I've had a few out.

ok, so...of course, the screw broke, even after pb blaster and heat from a torch. but i was able to use a file to flatten the sides of the screw so i could get a good grip on it with some vicegrips. i got it to turn and eventually got it out. i chased the threads, cleaned every thing up and re-installed the bleeder with some anti seize. it works, until i the replacement hex style bleeder gets here. any ways, i was able to bleed the system and button evrything up and and go for a drive. temps on the gauge stayed cool while moving at highway speed but crept up to about the 1 o'clock position when idling or driving in traffic. when i got home, i was looking to see if any coolant had escaped though the cap vent hose, nope looked dry. but i could hear a slight gurgling hissing noise. there's a tiny hairline crack in my overflow bottle. D'OH! anyone wanna sell me a good bottle? or know a good source for a new one?

Autohaus has new bottles for about $130. They're not cheap. I have found a couple of nice ones in the yard, and might be able to hook you up with a marginally-nice one a local friend has.

I'll check with him and get back with you.