Yes, so that upper coolant resevoir is the best place to fill. What I did when I did my rad flush... was that I prefilled the radiator, placed the cap back on for a tight seal. Then I put poured coolant in the upper resevoir. The upper res is the highest point in the cooling system, so as air pockets try to escape, they have no where else to travel but up. If you have that yellow cooling funnel it helps modestly because it will overflow.Hey all, sorry for the bump! I just replaced my radiator with a Koyo Rad, and changed my timing belt, water pump, thermostat, etc.
I am about to fill the radiator with coolant. In this video:
How To Change A Subaru DOHC EJ20 EJ25 Timing Belt - YouTube
He fills the coolant from the filler tank, and opens the radiator cap on top of the radiator as he's pouring. You can see some huge air bubbles come out. Will this help the whole process of burping? Also, if you fill coolant from the filler tank, does the coolant reach into as many parts as it can without the car circulating the coolant, meaning if I fill from the filler tank, does the radiator itself get filled, along with all the other components minus the plastic reservoir/over flow bottle?
This is a great thread and been very helpful!
Last question, if I use to spill free funnel to burp, I can leave that on the filler tank while I do the warm up/cool down process? Will it bleed the whole system or will I need to do the same thing for the radiator cap on top of the radiator?
The car has to run through fan cycles and that lets you know that the thermostant had probably already opened so you'll notice the coolant level getting sucked in--- away from the yellow funnel, don't ever let that run dry or you'll risk air pockets. As that happens, it starts to burp... blast the heater to make sure that you have coolant running through the core, should only take about 15-20 some odd minutes. Then in the morning, you can check your plastic overflow and fill it accordingly. Best done on a flat surface obviously.
If your heater is not blowing warm air yet, you have not cleared some air out of the system. Especially if it's intermittent cool/hot air... hope that helps... anyone else care to chime in would be great!
EDIT/ADD - By the way, morning after and through the week is essential to check your plastic overflow, I have a line that runs from the radiator to the plastic overflow on my 04STI, and sometimes I see it bubble/burp on like the 2nd or 3rd day, which is fine, then the next morning that plastic overflow level has gone down a moderate amount. If you notice that the plastic overflow looks fuller when the engine is warm, that is normal because of the pressure. 20,000 miles later, no overheating or leaks.