Changing coolant

diesel dunk · Post by **diesel dunk** » Tue Nov 15, 2005 5:58 pm

Anyone know how much coolant a 1.6 1983 vanagon will hold, I am replacing the head gasket and need to drain some of the coolant and thougt I might as well replace it all, as oil has been getting in across the head - need any good tips on draining system and bleeding - is there a drain plug on the engine as well, as the hoses go up and down all over the van and the thermostat housing isn't the lowest point by far - also, anyone know if there is a good way to refill and bleed the whole system - thanks in advance.

idhoho · Post by **idhoho** » Thu Nov 17, 2005 12:29 pm

Not sure about the vanagon but a 1.6 Rabbit takes about a gallon of coolant. Drain it at the thermostat/water pump hose. Refill the block first by using the upper hose and a funnel. Then fill the tank & radiator. Let it run till coolant is circulating, watch the level and add coolant as needed until full.

libbybapa · Post by **libbybapa** » Thu Nov 17, 2005 2:33 pm

It was at least 2 gallons last time I did it. I think some of a 3rd went in, but my memory is foggy.

Park on an incline (not totally necessary, but helpful) with the nose up. Check that the bleeder valve is a bleeder bolt (a channel in cut vertically across the threads). If it isn't, then cut a channel in it being carful not to mar the sealing surface of the underside of the bolt head. leave the bleeder open. Move the heater controls to hot (they should already be there from when you drained it). Fill the overflow tank. Start the van with the cap off the overflow and let it warm up until the thermostat is open making sure you keep topping up. Then rev the engine up to 2000+ and you will see the level in the overflow drop significantly. With the hand that isn't revving the engine keep pouring coolant into the overflow until it is flowing out of the bleeder valve at the front and making a big mess. Then prior to letting the rpm's drop replace the cap on the overflow. Go tighten the bleeder.

After you have driven it a few different times, when it is hot just after driving, open the bleeder slightly. The pressure will force any residual air out of the radiator. When only coolant comes out then tighten the bleeder. That is a good routine check (each oil change). If there is a significant amount of air then do it again after driving it again. If every time you check there is a sgnificant amount of air, then find the problem and fix it.

Andrew

diesel dunk · Post by **diesel dunk** » Fri Nov 18, 2005 7:29 am

Thanks for response - are you on about the bleeder valve on the rad or should there be one on the engine somewhere - I really don't know very much about this. The rad is higher than the engine, so I am worried that air might get stuck in the top of the head.

libbybapa · Post by **libbybapa** » Fri Nov 18, 2005 9:18 am

Yes, the bleeder valve is on the top of the radiator. I'd say it was on the passenger side but your verbage gives me the impression you might be on the other side of the pond. 133mm head. Looks like a bolt, but should have a chanel along its threads.

Andrew

diesel dunk · Post by **diesel dunk** » Wed Nov 23, 2005 12:23 pm

Let me just clarify, because I'm a bit of a dumb ass, when I start this process there is nothing but air in the whole system, I top up from the expansion tank only (is this what you refer to as the overflow tank?) and air will be driven out of the system all at the radiator. I understand that air rises in water, but the direction of the pipes is very up and down, so even though the top of the radiator is the highest point overall, there are lots of other high points eg. the cylinder head, where air can get stuck, how does this escape - or am I just being realllllly thick???

libbybapa · Post by **libbybapa** » Thu Nov 24, 2005 1:34 am

Yes, with the bleeder valve open then all the air will exit via the bleeder if the precedure is performed the way I described. The force of the waterpump pumping the coolant will cause almost all bubbles to flow to the radiator or else back to the expansion tank. There may even still be some air that accumulates in the radiator after running it, and that is why I recommended opening the bleeder when hot to allow the pressure in the cooling system to push it out. Any bubbles that do not find their way to the radiator will find their way to the expansion tank and then get forced out to the burp tank.

Andrew

diesel dunk · Post by **diesel dunk** » Thu Nov 24, 2005 6:25 am

I think I've nearly got it. There's two tanks, right? Which one do you refer to as the overflow - is it the one with the pressurised cap (expansion tank) or just the normal colcant reservoir?

libbybapa · Post by **libbybapa** » Thu Nov 24, 2005 11:01 am

The expansion tank is the one only accessible with the engine cover open. Yes, it has the pressure tank. The one accessible by the license plate door I call the burp tank.
You add coolant to the expansion tank while you rev it. Once it starts spilling out the bleeder valve in the radiator, before releasing the revs, replace the espansion tank cap. Then release the accelerator and tighten the bleeder. It can all be done by one person, but really two or three makes it a heck of a lot easier. One person runs the accelerator, one watching the bleeder, and one adding coolant and replacing the expansion tank cap. Good luck.

Andrew