Correctly bleeding cooling system ? 325i

[Mops]

Hello Guys.

Yesterday I left my car idling for about 10-15 minutes, and when I came back coolant temp was about 105 deg C as reported by aftermarket coolant temp (normally it runs 85-90). My car always run normal temp when drives, but always seem to run 5-10 deg hotter while stuck in traffic (i do that very relely). I do realize most likely thats cos of my stuffed fan (electric conversion on the way).

I've seen a coolant bleeding guide here, which I tried to follow recently when I was replacing timing belt and water pump. While I was at it I flushed the cooolant aswell.

Basicall the bleeding guide stated to undoo bleeding screw and wait until all bubles come out and only coolant comes out. So thats what I did on cold engine (no bubbles came out... coolant only). Then i started and let the engine warm up, I had hearing on and it was working good, I waited until the thermostat opened and it's all hot then i undid bleeding screw and no bubbles came out - just coolant. Convinced that it's correctly bleed I'm using the car now.

BUT !

Last nite I lost about a litre of coolant dorning that overheat and the reservior still showas all full, or maby minimal lost but IMHO it should be empty, as there was a big spill under the car.

Therefore I conclude my system is not correctly bled and that concernes me.

The other thing it.. .whats the biggest radiator I can install in E30 ? I think I'll need uprated cooling for the turbo conversion, so I can do that before I actually get a turbo.

[Simon]

When the cooling system is hot, it will show as being full in the tank due to the pressure, it will drop when left to cool.
Be very careful with the running temps on the 325i, never leave it get to the red on the guage, cracked heads are all to common on these.

Where was the coolant loss coming from? The overflow I assume due to the build up in pressure?

When you bled the system, did you open the cabin temp dial to hot? Does your car blow hot air? Try the bleeding proccess again, but try and park the car on a slight incline facing uphill, this should help.

Good luck!

[gcorky]

ditto m8 ,although my level is same hot or cold with no pressure biuld up in expansion,but it is a bitch to bleed often down to air in heater matrix but get there in the end .i too am going f.i

[Mops]

yeah, I had my cabin temp dial all the way to the hot. the stock gauge was showing just a tad over 3/4 when it was the hottest....

I have a theory that there's some blockage in the cooling system, as when driving it's not an issue. two things happen when driving... incerased natural air flow and incerased cooling system pressure due to water pump at higher revs. I bet thats the second one that is more of a factor in my case. An easy way to test it would be to let it warm up then rev it like 3k rpm's while standing and see what heppens. I didnt really have time/will to do it then, but as i got to 40 mph the temp slowly declined.

I havent told the whole sotry.. here is the more concerning part. when I saw it at high temp i immidiately shut off the engine. I whacked idiot passanger on the hear complaining he's not watching the gauges with the car running. 2 minutes later i wanted to leave. I turn the ignition, starter is trying to crank, but get stuck. sounded like it tries to turn but doesnt have enough power. that was really concerning. after 3 minutes, we got a bunch of bystanders to give me a pusch and I started from rolling 2nd gear first try. I never seen a siezed engine, BUT i was terrified it might be it. later on while driving on highway I had normal temps.

My another concern is that if there's air in some parts of the engine, there there's no water there hence no cooling.... co the gauage might be showing all good (temp at engine coolant outlet), while all different temps around the block.

I didnt located the leak at the time, but the alternator was wet, and generally the area unser thermostst... couldhave been leak through bleeding valve - i didnt do it up that hard.

Here's my plan:
drain whats in there (kinda sux, cos it's fresh coolant, but then again somewhat dirty), flush it good. Run just plain water (it's summer here on souther hemisphere, besides it never get's below 0 in auckland) for few days with some strong detergent/rad flush/etc. If any contamination spotted then flush and repeat again. Once happy with the progrss then refill with proper coolant.
Aparently 325i e30 takes 12 liters of coolant....
can somebody confirm ?

[MONSPORT42]

I found a good tip for bleeding is to undo the clear overflow reservoir from the car and lift it as far as it will go until system full and no bubbles showing and then refit it.. Essential to have engine running and heater on full blast to get the sytem full.