Best way to bleed coolant system without a bleeder valve?

[haaken675]

Hey everyone. I finally have my turbo m52 swap running and am looking to actually make my first test drive hopefully tomorrow. I have had the car running multiple times for upwards of 10-15 minutes, but I just can't seem to get the coolant system to bleed properly. I know these cars are notoriously hard to bleed, I have had several e30's e36's, e46's, and e39's, but I just can't seem to get this one to bleed.

I have an m52b28 swapped into my car with a 3" triple pass radiator, heater core deleted, throttle body heater lines deleted, and a late model expansion tank. I have an new 80 degree thermostat installed as well as a new waterpump with aluminum thermostat housing.

Unfortunately with this setup there isn't a bleeder screw anywhere. Does anyone have any tips for getting the system bled? I am going to try and jack the front end up tomorrow and run it for a bit to see if that pushes the air out. I have read online that might work, but nothing else really useful. Is there a way to pressure bleed the system like you would do to brakes?

[Danny]

Undo the upper rad hose at the radiator and fill the coolant system from there. Reconnect the hose and start the car. Add coolant to the expansion tank and leave it open. Run the car with the heater on full blast. Squeeze the upper rad hose and you’ll see bubbles come out of the expansion tank. It’ll take a bit but you’ll get it bled. If you still have issues remove the thermostat and drill a small hole at the 12 o’clock position to aid with air passage.

[e30austin]

Fill the cooling system through the upper radiator hose. When full, reconnect it to radiator, and remove small hose leading from expansion tank to top of radiator. Fill expansion tank, until you have nothing but water coming out, no air bubbles. Start the car, elevate the front end and crank the heat on full blast, until engine reaches operating temperature.

And yes, as mentioned above, a 1/16" hole in the thermostat (no bigger) will help to alleviate any possible air pockets.

[haaken675]

I have actually done all of the suggested above aside from the drilling of a larger hole in the thermostat.

[Danny]

Just keep workin it. It’ll bleed. You could also enlist the help of someone to hold the rpms around 2k until you get the thermostat to pop open.

[haaken675]

That’s pretty much what I had to do with my e39. I guess I’ll jist have my wife sit in the car and whatch tunersrudio, afr gauge, and the temp gauge while I watch and check the cooling system. I don’t think she understands the concept of the thermostat opening and air bleeding out of the system, lol. I just got it running on megasquirt so I’m slightly paranoid about something going wrong if I don’t watch everything.

[ButtJuice]

Does putting the heater on full blast still work without a heater core?

[pazi88]

You only need to open completely the bleed screw on the radiator when you fill up the coolant system SLOWLY. When coolant comes from the bleedscrew hole instead of air, close it. Put/remove enough coolant that the radiator resevoir level is at the cold line and go for drive. When the car has cooled down after the first drive, you may need add some coolant, but the bleeding of the system is really this easy. If the method doesn't work, you have something wromg in your coolant system. For example if heater hoses are backwards, it causes lot of bleeding broblems.

EDIT ah ok. You didn't use radiator that is meant for m5x engine if it doesn't have bleed screw. No idea how you can easily bleed the system without it...

[haaken675]

Does putting the heater on full blast still work without a heater core?

No, it definitely does not work, lol. Especially when the heater box is completely removed along with the blower motor.

and also, the radiator I have is meant for an m5x motor. It is an all aluminum z3m radiator copy.

[Caperix]

Vacuum bleeders are getting cheaper if you have access to an air compressor. Just pull a vacuum on the whole system & open the fill valve, no bleeding needed.

[TobyB]

:loco:

I hear the pros use nitrogen...

t

[haaken675]

Vacuum bleeders are getting cheaper if you have access to an air compressor. Just pull a vacuum on the whole system & open the fill valve, no bleeding needed.

This is what I have been wondering about. I have searched and searched online and hunt come up with anyone vacuum or pressure bleeding the coolant system. I’m going to find a way to give it a try.

[haaken675]

Also, turns out I’m an idiot when using search key words, lol. I was so set on using the phrase “pressure bleed” that I always fake up with nothing. As soon as I typed in “vacuum bleed” it automatically recommended the coolant portion...

[e30austin]

A cooling system pressure tester will do ultimately the same thing. FYI.

[Caperix]

I've had better luck getting all the air out using vacuum then pressure. You can try filling the reservoir to the very top & letting it sit open overnight, sometimes that will let the air work it's way out.