engine and drivetrain How to bleed the cooling system

[B-Doon]

I just replaced the flex hose underneath the alt that goes from the water pump to the intake....when I pulled it off most of the coolant drained onto the engine and the garage floor.....so, now that everything is back together, do I need to "bleed" the cooling system after I refill the coolant? And if so, How????? I couldn't find a bleed screw on the thermostat....Ich brauche hilfe fur mein auto.

Brian

72 inka

[PSloan]

No, you shouldnt have to bleed it. Just top it off while the car is running with lukewarm 50/50 mix.

If you have never flushed it though, you may want to. There is a bolt under the exhaust manifold that is the drain.

[PSloan]

BTW - what did you decide to do about the rusty wheel arches??

[B-Doon]

I think she's too rusty to replace the arches...I got underneath and saw what appears to be rust extending into the inner wheel houses, quarter panels, and the shock towers....I'm going to POR-15 all the out of sight areas, make a fiberglass fix, and do a cheap repaint of the affected areas...there are so many other areas that need attention, it would be cheaper to get a rust free shell.....I've got small signs of damage all around from hail...something fell on the roof, a minor rear end hit, the front end was replaced in the 80's, rusty doors and quarters, and very crunchy rockers....come to think of it, why did I buy this thing...

Peace,

Brian

[PSloan]

Yeah sounds like a shell transplant is in line. The car looks great, though.

[Zenon]

I just replaced the flex hose underneath the alt that goes from the water pump to the intake....when I pulled it off most of the coolant drained onto the engine and the garage floor.....so, now that everything is back together, do I need to "bleed" the cooling system after I refill the coolant? And if so, How????? I couldn't find a bleed screw on the thermostat....Ich brauche hilfe fur mein auto.

Brian

72 inka

You may get lucky (raising the front of the car so the rad is the highest point when you fill is helpful) but my experience is that four out of five times you will have to bleed it, at least to get the heater working.

What I do is make sure the heater valve is wide open (heater set to hot), pressurize the system to 14lbs using a cooling system tester, then carefully loosen a hose clamp on the heater hose at the heater valve (the highest pont) and then maybe pinch the hose with pliers until it leaks. Any air will hiss out and escaping coolant will tend to look frothy until the air is cleared - then it will come out clearer and quieter. Sometimes I have to stop and re-pressurize if there was a lot of air, or repeat the procedure on the other heater hose where it meets the heater core.

You can also do this without a tester by letting the engine heat up to build pressure, but that might be bad for the engine if there is a major airlock and hard on you if you get scalded by hot coolant. You also don't get another chance until the engine cools down again.

regards,

Zenon

[SteveJ]

I have had good luck by drilling a small (1mm) hole in the diaphragm inside the thermostat housing. It is just enough to keep the air from being trapped down below. Otherwise you may have to massage the lower hose when things get hot, trying to get the thermostat to "break" free. Not fun when things get hot.

Later thermostats like those on an E30 already have a little bleed hole in them. The McCartney book has a little write up on drilling a bleed hole.

[Mike Self]

you can replace the drain bolt in the radiator with a drain cock; same with the block fitting. Either solder an appropriately sized drain cock into the radiator drain hole, or take one with SAE threads and re-thread to match the drain plug (8x1 metric threads, if I remember correctly). For this you may have to use an adapter.

As for the block, I took the original metric drain bolt to an auto parts store and found a brass drain cock that would thread in. Use Teflon tape, and the soft brass threads will conform to the metric block threads well enough so it won't leak. Oh--get drain cocks with nipples so you can slip a length of hose over 'em so the coolant will drain nicely into a bucket...

I've never had any luck finding metric drain cocks in the US.

cheers

mike

[Guest Anonymous]

you just open the radiator cap and squeeze some of your hose and u should start to see bubbles coming up in the radiator