I'm Bleeding Still

[angusbn]

So how many times did you have to bleed your M30 cooling system to get rid of the air pockets? I'm at 12 times now and counting and it's still running hot.

1989 535i M30

[Sixdown]

I did it twice and I was set. If you're having to do it 12 times, you probably aren't doing it right, or something is leaking air.

[genphreak]

So how many times did you have to bleed your M30 cooling system to get rid of the air pockets? I'm at 12 times now and counting and it's still running hot.

1989 535i M30
First time I did it I needed more courage; the head seemed to get too hot and I didn't want to drive it. Kept thinking I put something round the wrong way.

Never found a good procedure for a beginner; even started drilling the thermostats to get it to bleed quicker. Never do these days... but here's my procedure (hope it helps)

Tip: Always make sure the thermostat is spring side towards the engine (else it won't open till the engine is way too hot) and that all connections are clean and smooth. Deposits of oxidation and dried coolant around the hose ends should be properly cleaned. Don't overtighten connetions expecially on the plastic necks. ie on radiator hoses.


Always leave the cabin heater temp controls open to the max.
Always drain the block as well as the radator-always.
Plug both.
Fill system with coolant- only prestone, BMW, Mercedes, Saab, (Volvo?) blue. There is another one we can't get down here that is yellow like the Prestone. 2/3 water or 50/50 or as needed for your climate- if you have hard water in your area use more, but you don't need to knw that as you should be using distilled anyway (its often false economy trying to scrimp on a bimma...)
Open drain on water neck (or if a M50/M60/M70) on the radiator. Keep filling resovoir with coolant, but it inevitably fills and then holds its level without any coolant coming out of the bleeder.
Run engine with the bleeder open. Keep gradually filling with coolant
Eventually coolant comes from the bleeder. Close bleeder
Shut down.
Open the bleeder
Top up gradually, until clean stream of coolant is observed- no bubbles. Close bleeder
Run engine, watch system pressurise.
Look for leaks :) You did change every one of those bulging hoses didn't you?
Note if lower radiator hose gets hot, if under 25degrees this may take some time, and driving the car a short way will help.
Check all connections again.

Check after the next drive. Your coolant level will drop to between min and max if you've done the right thing (excsss will be expelled via the overflow). If you are having problems pressurising there's a leak which may blow coolant and/or steam, often only obvious if big enough or hot enough, but you cleaned all the fittings and hoses and gasket faces to insure against such troubles so this cannot happen :)

Oftentimes the cooling system will only allow the engine to overheat in traffic on a hot day with the AC on, remember in your Biimmer's book this is the best time for a break down :DDDD

[Rus]

There is definitely something wrong if you are having this much trouble bleeding the M30. I just rebuilt my cooling system and it took me all of 20 minutes to get it topped up and air-free. What I normally do is open the bleeder and start adding coolant to the reservoir. Eventually you'll see coolant come out of the bleeder. Close it and continue adding coolant. If you have a bleeder on one of the heater core lines, open it until coolant comes out of it too. I have an aftermarket heater hose with a bleeder, but you may not have this. Once the system is topped up, squeeze the top radiator hose energetically and watch for air to go into the reservoir. Top up if necessary. Now start the car and keep an eye on the level. Open the bleeder periodically to make sure there is no air collecting in the t-stat housing. Also keep an eye on the radiator overflow line. As the engine warms up, you should see a stream of coolant going into the expansion tank neck. If this isn't happening, check to see if that line is clear. Run your heater at max settings while you're doing the initial bleeding. Feel the heater hoses and make sure they are warm. Squeeze them to help get the air bubbles moving. Eventually you should see a steady stream of coolant going into the tank neck, heat from your heater and no air bubbles from the bleeder. At this point, check the level and either let the car cool down or put the tank cap on and go for a drive. Over the next few days you may have to top off the reservoir a bit. This is more or less how my car behaves and I've bled the system this way three or four times already. Don't let your engine run hot during the bleeding either. It should not be overheating when you're filling the system unless you have an air pocket somewhere. HTH

[BigKriss]

i keep the car idling after it's topped up with the heat on full. it never goes over 1/2 way (the coolant temp gauge) and looks okay,i take it for a short drive and it starts going near 3/4, then i pull over and let the coolant come through the bleed screw until no more air comes out. then i'm done. check in a few days or next drive so see if you need to put more coolant in.

[angusbn]

I think I'll get the car up on ramps and slowly add coolant to the until it pours out of the bleeder screw. Squeezing the upper rad hose is a good idea too. It's a PITA for sure.

[whiskychaser]

I have an aftermarket heater hose with a bleeder
I think this is a great mod.

[Rus]

I think this is a great mod.

Oh yes. I bought a hose without this nifty device built in and ended up saving the old valve and installing it into the new hose. The ~$40 diffference in price is augmented by the reusability of the bleeder piece.


I think I'll get the car up on ramps and slowly add coolant to the until it pours out of the bleeder screw. Squeezing the upper rad hose is a good idea too. It's a PITA for sure.

Angusbn,

I would suggest against getting the car on ramps to add coolant. I tried to do it this way about a week ago and couldn't get the radiator to fill up due to the angle. Pushed the car off of the ramps and voila! Bleeding the system has never been an issue with my car, to be honest. This last time I did it was the worst because of the ramps and some trapped air in the heater lines. A bit of frantic running around and squeezing hoses while operating the bleeders had things fixed up in about half an hour.