Air bubble in coolant system, moment of stupidity

[kramerica5000]

So as I was flushing the coolant system this weekend, I had a moment of extreme stupidity and forgot to bleed the system for air.

I drove the car twice like this. The first time was for about 4-5miles or about 5-6min when the engine was cold. The second time I drove it (about 20min later engine warmed) is when I noticed the car getting hot after about 2-3 miles.  Before it hit the red I pulled over and shut it off. I opened the cap to the resevoir and some air bubbles came out. I drove it back without overheating.

So my question is, do you think that driving it 4-5 miles with an air bubble in the system could have damaged anything? Everything seems fine, but I am really worried that I overheated it on that first drive.

I'm so pissed at myself for being so stupid! AAARRRGGGHHH!!

[M42boy]

So as I was flushing the coolant system this weekend, I had a moment of extreme stupidity and forgot to bleed the system for air.

I drove the car twice like this. The first time was for about 4-5miles or about 5-6min when the engine was cold. The second time I drove it (about 20min later engine warmed) is when I noticed the car getting hot after about 2-3 miles.  Before it hit the red I pulled over and shut it off. I opened the cap to the resevoir and some air bubbles came out. I drove it back without overheating.

So my question is, do you think that driving it 4-5 miles with an air bubble in the system could have damaged anything? Everything seems fine, but I am really worried that I overheated it on that first drive.

I'm so pissed at myself for being so stupid! AAARRRGGGHHH!!

Don't sweat it.  As long as you don't overheat your motor, it's not a problem.  The air won't cause any issues.  Actually, driving the car probably forced all the air back into the reservoir.

The proper way to bleed the system of air is to seal up everything tight with new coolant in it, and run the car at idle and under load (2,000 rpm) for a few minutes till engine is warm... then back out the bleed vent screw at the top of the radiator (it's right next to the reservoir cap) untill bubbles come out.  Rev motor to 2,000 or so, and let bubbles and coolant drain.  Tighten it some more and repeat till you see just straight coolant coming out (no bubbles).  Top up and your done.  You may need to do this once more after a few days of driving to make sure the system is 100% purged, but you may have just done this.  

I don't reccemend opening up the coolant reservoir cap when the engine is so hot, as you could get scalded with hot coolant/water!  Just use the bleeder valve on the top of the expansion tank.

See write up here (save this site in your favorites too as it's a great resource!).  
http://www.esatclear.ie/~bpurcell/318ismaintenance.html#bleed

Hope this helps!

[kramerica5000]

Don't sweat it.  As long as you don't overheat your motor, it's not a problem.  The air won't cause any issues.  Actually, driving the car probably forced all the air back into the reservoir.

The proper way to bleed the system of air is to seal up everything tight with new coolant in it, and run the car at idle and under load (2,000 rpm) for a few minutes till engine is warm... then back out the bleed vent screw at the top of the radiator (it's right next to the reservoir cap) untill bubbles come out.  Rev motor to 2,000 or so, and let bubbles and coolant drain.  Tighten it some more and repeat till you see just straight coolant coming out (no bubbles).  Top up and your done.  You may need to do this once more after a few days of driving to make sure the system is 100% purged, but you may have just done this.  

I don't reccemend opening up the coolant reservoir cap when the engine is so hot, as you could get scalded with hot coolant/water!  Just use the bleeder valve on the top of the expansion tank.

See write up here (save this site in your favorites too as it's a great resource!).  
http://www.esatclear.ie/~bpurcell/318ismaintenance.html#bleed

Hope this helps!

Thanks for the reassurance. I did end up bleeding it correctly later on and I used the BP's site as the guide. The worse thing is that I printed out his whole maintenance section and read the guidlines for everything I did that day BUT the radiator flush. Yeah, I was careful about loosening the reservoir cap. I just loosened it a little to let the air come out. At the time I didn't know about the bleeder valve even though it was right there. Two weeks with the car; I better get smarter.

[M42boy]

At the time I didn't know about the bleeder valve even though it was right there. Two weeks with the car; I better get smarter.

Takes time man!  I bought my car and drove it all warn out for a few months before I did anything to it.  In fact, what you just did is exactly where I started.  Mine wouldn't warm up all the way (bad t-stat).  So I replaced it, the flange, flange gasket and did a radiator flush.  

Now all that coolant is back out of it again as the car sits in pieces on the garage floor.

Your car sounds almost exactly like mine.  I thought mine was perfect till I had it a while and found a whole laundry list of things to fix... and keep finding them.  But, that's part of the fun of BMW ownership I guess.  Constantly something to work on.  
Keeps me occupied!  

How is your suspension?  Mine was totally warn out.  Needed new shocks and most of the bushings were toast.

[kramerica5000]

Hey, I think I may have a similar problem. My car stays cool according to the gauge. It hovers just past the blue area. Is that where your's stayed? Where is it normally?

What happened that yours that its in pieces now?

Yeah, despite only having 87k miles, mine definitely has some issues. I'm still trying to sort out what needs working on. Last weekend, among other things, I had to replace the output seal on the diff. Today I noticed that I can't downshift into 2nd at higher speeds without grinding gears :eek:

The suspension is actually pretty tight as far as I can tell, but age takes its toll. Redoing it is definitely on the list.

Takes time man!  I bought my car and drove it all warn out for a few months before I did anything to it.  In fact, what you just did is exactly where I started.  Mine wouldn't warm up all the way (bad t-stat).  So I replaced it, the flange, flange gasket and did a radiator flush.  

Now all that coolant is back out of it again as the car sits in pieces on the garage floor.

Your car sounds almost exactly like mine.  I thought mine was perfect till I had it a while and found a whole laundry list of things to fix... and keep finding them.  But, that's part of the fun of BMW ownership I guess.  Constantly something to work on.  
Keeps me occupied!  

How is your suspension?  Mine was totally warn out.  Needed new shocks and most of the bushings were toast.

[e9nine]

Normal temp guage readings seem to be between 1/4 and 1/2 mark.

When downshifting to 2nd, even with synchros you sometimes have to rev-match. How fast are you going when you try downshift? What's the condition of your transmission mounts?

[kramerica5000]

I think I know what the problem is. I put mobil 1 synthetic gear oil in the tranny and I think the viscosity is too high for the synchronizer to work (my dad had the exact same problem with his miata, which is how I figured it out). I'm ordering some Redline GL-4 and will put it in this weekend, hopefully that should get it working right.

Normal temp guage readings seem to be between 1/4 and 1/2 mark.

When downshifting to 2nd, even with synchros you sometimes have to rev-match. How fast are you going when you try downshift? What's the condition of your transmission mounts?

[M42boy]

I think I know what the problem is. I put mobil 1 synthetic gear oil in the tranny and I think the viscosity is too high for the synchronizer to work (my dad had the exact same problem with his miata, which is how I figured it out). I'm ordering some Redline GL-4 and will put it in this weekend, hopefully that should get it working right.

My temp guage, now functioning properly, hovers just below the 1/2 mark.  Straight up and down is correct operating temp for most BMW's IMHO.  Only problem now is mine takes forever to reach full operating temp!  Not sure why it takes so long to warm up.

As far as the transmission, that definately sounds like a synchro problem.  Do a little research or make a few calls to make sure you are putting in the correct fluid.  I was under the impression it was Redline MTL or MT-90 that has the friction modifiers to work better with synchros.  Mobil 1 actually makes a racing fluid that has the same thing as well.  That's what's going in my case once it's all back in the car.  

This car is pretty easy to downshift with, but in the meantime, just double-clutch to match the revs in a low gear like that.  I had a Porsche 944 that was impossible for me to get in 2nd on the track with.  Part of it was my lack of heel-and-toe skills, and the other I think was a mechanical problem with the clutch and/or transmission.  But, it was a very low reduction gear, which didn't help.  :rolleyes:

[kramerica5000]

Yeah, mine never even reaches the 1/4 mark, no matter how long I drive it. I got a new t-stat on the way for this weekend.

I'll report back on whether or not the redline MTL helps. If it doesn't, I'll just get back into the habit of double clutching.

I picked up the Mobil 1 at Advanced Auto. It was pretty much the only thing they had. I don't think its the best stuff because I believe its GL-5, even though it doesn't say that on the label. I'm learning that this car is a little too picky to use just get anything.

My temp guage, now functioning properly, hovers just below the 1/2 mark.  Straight up and down is correct operating temp for most BMW's IMHO.  Only problem now is mine takes forever to reach full operating temp!  Not sure why it takes so long to warm up.

As far as the transmission, that definately sounds like a synchro problem.  Do a little research or make a few calls to make sure you are putting in the correct fluid.  I was under the impression it was Redline MTL or MT-90 that has the friction modifiers to work better with synchros.  Mobil 1 actually makes a racing fluid that has the same thing as well.  That's what's going in my case once it's all back in the car. ...

[M42boy]

Yeah, mine never even reaches the 1/4 mark, no matter how long I drive it. I got a new t-stat on the way for this weekend.

I'll report back on whether or not the redline MTL helps. If it doesn't, I'll just get back into the habit of double clutching.

I picked up the Mobil 1 at Advanced Auto. It was pretty much the only thing they had. I don't think its the best stuff because I believe its GL-5, even though it doesn't say that on the label. I'm learning that this car is a little too picky to use just get anything.

The T-stat job is really straightforward, but you may want to get a new coolant flange gasket first because you break that seal when you go to change the thermostat.  

I HIGHLY suggest taking time to remove the fan shroud and radiator fan first as it will make the job much easier.  I didn't, and it can be done with all that stuff in there, but was a pain to access those lower bolts.