Coolant Replacement, minus the big air pockets :-)

[Setright]

Editted! Addition in bold:

 

 

Having replaced coolant on my boxers many times, I have been searching for the right way to get all the old fluid out and getting as much new fluid in, without having to burp the system for a week after I'm done. I think I have finally cracked it!

 

Draining

 

Drain the radiator as far as possible with the little "faucett", and then detach the lower hose from the radiator. (If you are like me, replace any coolant hoses that you remove, and use stainless steel clamps on the new ones)

Even more fluid will drain from the radiator, and some will drain from the engine block. Detach the upper hose from the radiator, and run clean water through the rad until it comes out of the bottom clear in color.

 

Now, I do not contest that the best way to flush the engine block is by unscrewing the two drain plugs, but these are often seized and could turn into a source of trouble if you strip the threads or if they won't seal tight when you screw them back in. SO, I jack up the rear of the car until the engine block is tilting slight forward, ie. wheels about 6 inches off the ground, unscrew the thermostat housing, and let the old fluid run out through the thermostat opening. (Needless to say, I replace the thermostat gasket)

Run clean water in through the upper hose until clear water comes out of the thermostat opening. Leave the car in this position until it stops dripping water.

 

Remove the expansion tank and flush it, there will be plenty of "snot" in the bottom of it! Rinse the hose too. Install the tank again and fill to the FULL mark.

 

 

Filling

 

Close up the bottom end of the cooling system, ie. thermostat and lower hose. If possible, perform the next phase on a slight incline, car pointing upward.

Get a funnel with about 10 inches of half-inch diameter hose on the end of it and slide this down the upper hose in toward the engine block. I do this because bending the upper rad hose causes it to collapse and that makes pouring coolant into it impossible. Pour your preferred coolant directly into the engine block. Pouring slowly, and pausing along the way will help keep air from being trapped inside the block. It should swallow at about two litres before it starts to rise and threaten to come out of the hose. At that point, attach the upper hose to the rad and continue to fill slowly through the rad cap hole. Once it seems full, start the engine, let it run for twenty seconds and shut it off again. This will dislodge the few air pockets that are unavoidable and the fluid level in the radiator should drop a little after the burp, top it off.

Start the engine again, and let it run until the radiator fan starts running, be patient! When then fan starts running, top off the level in the rad and install the radiator cap - and bleed screw if there is one. During the warm up, a small amount of coolant will spill over the rad filler neck, have a cloth to absorb it.

 

Take the car for a shortish run, just a few miles to get it fully warmed up, and park it on level ground. Check hoses for leaks of course, and let it cool. This will take a number of hours, overnight is good.

In the morning, note the level in the expansion tank, it will probably be a little lower than FULL. Fill to the FULL mark, and you're all set.

 

Obviously, you should check the level in the expansion tank for a few days afterward, but there shouldn't be any problems. Resist the temptation to open the rad cap, this will only interfere.

[friendly_jacek]

Is this applicable to newer cars (2000+)?

 

I wish this board had a sticky function!

[Setright]

Yes it is. The big secret is filling via the top hose and idling til the fan comes on.

[ShawnW]

Simpler:

 

Buy the funnel referenced in my prior post. Available many other places but cheapest here I think....http://www.sjdiscounttools.com/lis-22150.html This prevents spilling, burps the system and automatically removes air pockets.

 

To drain system, remove petcock and thermostat housing and remove thermostat. Remove radiator cap and replace with spill free funnel. Remove overflow bottle and dump out its contents and set the empty bottle onto the radiator again.

 

Replace thermostat and gasket with OEM and replace hoses.

 

To fill: Place heater selector on hot, and turn fan to 2nd speed. Fill system until spill free funnel has 4" of coolant stored in it and start engine. Idle engine until radiator fans come on and heat coming out of the vents is hot and observe that the temp gauge is not above the 1/2 mark. Place stopper in spill free funnel, remove it from the filler neck and drain remains into overflow bottle.

 

Coolant should be 50-50 mixture unless you never drive the car at a temp less than 32 degrees. Most people take their car somewhere cold in the course of a year.

[Setright]

Simpler if you have the gear available. And why pay for it?

 

 

The heater matrix always recieves coolant, there is no valve in it, so the only thing you achieve by having the cabin heater on is a longer warm up time.

 

Cabin heat exchangers had valves way back in the bad-old-days, and the output was very hard to control. That's why they have constant flow these days, with a flap to guide air through it.

[OB99W]

Buy the funnel referenced in my prior post. Available many other places but cheapest here I think....http://www.sjdiscounttools.com/lis-22150.html This prevents spilling, burps the system and automatically removes air pockets.

Thanks for the info, but the link as given results in:

Page Not Found

The page you were looking for has either been renamed or removed. Please use our search box at the top of the page to find the products you are looking for.

 

Seems there's a stray hyphen above. However, this seems to work:

http://www.sjdiscounttools.com/lis22150.html

 

--OB99W

[Scottbaru]

My BMW is completely conventional in comparison.

My 740 has an electric pump and valves, pulling coolant from the engine and routing it through two heater cores. Lots of little oddities in this car, but well done and nice to work on.

 

No mention of what coolant yet? Yeah, you can always default to OEM, but that tends to be $, and no dealers anywhere near me. Prestone's site says the phosphate in their coolants is a corrosion inhibitor, but tends to settle minerals out of the water. They say it's not recommended by euro manufacturers because they have hard water over there, but Prestone says it's ok over here. Huh? Anyway, they offer Dex-Cool, phosphate and silicate free. It was designed for GM, but GM now recognizes that it does more damage than good, bummer. Lots of info on Dex-Cool damage on the web. I'm running it in three of my four cars, guess it's time to change some coolant. Zerex has some good coolants, recommended by BMW and enthusiasts. I don't know who carries it, haven't looked yet, but that'll be my next coolant.

 

I always run distilled water with my coolant, but rarely can I get all the hose water out. Even with opening the block drain and blasting with air, I usually come up a gallon short on what I should be getting in there. I always put in half the capacity of coolant first, then water, so I know I have a 50/50 mix.