Coolant bleeding issue

[Leonstt]

Guys,

I have a problem trying to bleed my coolant system.
I flushed my cooling system today using compressed air and tried to get as much old coolant as possible out of the system. Everything went pretty well until I tried to bleed the system. My car is a 1990 E30 sedan with M52B28 swapped. The cooling system is using a remote expansion tank, located where the battery used to be (on the passenger side fire wall).

What I did to bleed the system is by filling the expansion tank to the brim and wait until the system sucks all the liquid. I left the cap off. However, after 5 min or so, I didn't see the coolant level drop and my temp gauge was hovering around 3/4. So i switched the engine off, then all the coolant was sucked in to the system.

Then i topped it back up and restart the engine and waited. Basically same procedure as before. But this time I notice that my coolant in the expansion tank was boiling like crazy and started to overflow. At this point my gauge was showing 3/4 again. So I swtched my engine off, again the coolant got sucked in. I didn't see any leaks anywhere. I let my car cool down.

Then, As I started the engine for the third time, the idle was pretty rough. Like its misfiring. But there was no smoke coming out of the exhaust. So I drove my car into the garage and immediately switched the engine off. At this stage, all my coolant in the tank was gone. All in the system. So I need to get more coolant and for the time being I'm not planning to start my car

I'm at lost right now. Anyone has the same experience as me? Mind sharing your thoughts as what cause my engine to misfire? Does air in the cooling system cause the engine to misfire?

[tomstin]

Typically with an E30 it is recommended to raise the front of the car, turn the heat on high and bleed the air with the bleeder screw. I'm not familiar with the B28 in an E30. I would remove the spark plugs and see if any are fouled. Maybe a compression test to be sure you didn't do any damage.

Why were flushing the coolant system? Was there a problem before you stated this project?

[ADEN]

Missfires happen when engine is really hot if you let it cool it should start fine otherwise you have a problem. Also check your oil and coolant for signs of mixing.

I found filling coolant after full drain from the expansion tank is useless and needs repeating until air is out and car overheats easily fisrt time.

I found that filling from the upper coolant hose attached to radiator is the best way to fill more than 90% of the system from the first time.

Open the hose and raise it up as far as you can then pour coolant (expansion tank cap off) until it is flooding from both hose and expansion tank then quickly install it back and tighten the clamp, then fill the expansion tank if needed then close cap tight and fire up the engine.

You're done.

If temp still going up then you must have left the car without coolant and the thermostat got rusted stuck.

You may remove it and do the hot water pot test in the kitchen ( google how) somtimes oil and some exercise can get it to work again if you can't afford one at the time.

Another thing to check for is the small hose in the neck of the expansion tank it should squirt coolant when cap off and engine reving if not then it is clogged and causing trapped air not to bleed from the system.

[cory58]

Did you open the bleeder valve on the thermostat housing?

[ADEN]

Did you open the bleeder valve on the thermostat housing?

Cory mentioned the most important thing in bleeding (thr bleeder screw) this should be opened will filling coolant until a steady stream of coolant flowing from it then tighten it well.

Start engine then wait until temp gauge in the middle rev the engine to 3k and hold it, open the bleeder again for like 30 seconds the close it.

You are Done.