Coolant not burping after replacing radiator?

Hello all,

I just replaced my radiator (had the infamous hairline crack at the top of the radiator as I've seen in a few posts). Anyway, after replacing the radiator with a new koyo, these were my steps:

1. Filled the overflow basin to the full line with 50/50 mix of Toyota red coolant and distilled water.

2. Filled the radiator to the top.

3. Moved the temperature gauge to the "hot" position, and made sure the fan was set to "off". [does it matter what direction I have the switch set to? (ie. face, floor, defrost with floor, etc.)]

4. Turned the car on and let it idle until the fans came on, then checked to see if bubbles were coming out of the top of the radiator with the cap off and funnel still in.

My issue is that the coolant in the overflow basin is still at the full line and has not moved. No bubbles were coming out of the top through the funnel, so I added a small amount more so the bubbles would be more visible, but still, no bubbles. Also, the top hose did not seem to have any coolant in it, as it was pretty flexible, not stiff at all.

My concern is that it was not properly burped.

I should note that I also replaced the thermostat in the process, and made sure it was put in the correct way.

Shouldn't the top rad hose be stiff when it gets up to operating temp?

Also, shouldn't I expect some of the coolant to be pulled out of the overflow basin when it gets up to temp?

When I was at the dealership, one of the Toyota mechanics told me that when I install the new radiator, before I fill it, to disconnect the top hose from the radiator end, and fill it with coolant, then connect it back to the radiator. I did not do this. Would doing this help in removing air bubbles from the system?

Obviously, I'm worried about overheating. Could my thermostat not be opening properly? Did I miss any steps, or do something wrong?

Thanks again,

Zayne

 

Remove both of the heater hoses at the firewall and pour it in one side until coolant starts pouring from the other side. Check your coolant level at the rad filler neck after that and top off if needed, you should ideally be good to go. Just monitor your temperature guage or if you have to, monitor the temp guage on a scan tool as well and make sure it stays steady around 185-205* F. I'm not sure what the coolant temp spec is for 1st gens.

 

The upper hose should be hot, not stiff.

Coolant goes in the overflow when hot, back in the engine when cool.

If you have heat, your heater core isnt air locked.

 

The expansion tank can't return coolant to the system unless its pressurized.

 

^^^this^^^

 

X2
I did this and it worked for me. Some vehicles actually have a hole on the heater hose At firewall that you use to burp it. By disconnecting that hose slightly until coolant seeps out. Then reconnect. But I just disconnected the line completely, poured coolant down until it came out and reconected quickly. Burped. I didn't worry about pouring it in any other way besides the fill neck. And of course the heater hose.

 

This is very incorrect.

It should be hot and hard to squeeze, so in a sense, yes the hose should be stiff. 15-16lbs is typical of most cooling systems.

If the cooling system is not under pressure, as mentioned above it cannot return coolant to the overflow tank if it needs to.

 

Do you mean that because my radiator cap is not on (because I have a funnel in the radiator to top off) that the system is not pressurized and therefore cannot return fluid to the overflow tank? Would the cap being off of the top of the radiator also be why the hose is not stiff?

 

How would I know if the system is pressurized? would keeping the radiator cap off in order to burp it keep it from being pressurized?

Also, should I have poured coolant up to the "full" line in the overflow basin when I was refilling? or should I have just filled up the radiator?

 

Your system won't pressurize with the cap off. Sometimes if a system is hard to bleed you can park the truck on a hill, radiator high. That will help. If the t-stat you put in has a bleeder hole on top the bubbling / burping will be less drastic. When you're up to temp, the top rad hose, and both heater hoses should be hot. I usually turn on the heater fan to make sure it's blowing hot air.

 

I did notice that the top rad hose was hot, just not stiff.

I'm assuming the thermostat did have a bleeder hole in the top, a little dangly thing underneath the rim. I read that you should position the dangly thing at about 11 o'clock when you install it, I'm assuming that is probably why.

 

Put all hoses on properly fill up radiator till you cant fill it any more and you dont need funnel just pour it nice and slow, then fill the reservior till its full put the cap on start the engine let it warm up make sure the top rad hose is hot take it for a trip around a few blocks park it pop off rad cap slowly as it will be hot and pressurized so use a rag as well pour in more coolant as needed shouldt be a whole lot put cap on, shut hood, done, doesnt get much more simple then that

 

Correct. It's why caps have pressure ratings of x lbs. Pressure raises the boiling point as well. When the pressure rises above the caps rating, it opens and allows coolant to overflow to the tank. When the pressure drops it sucks it back in. In a 'healthy' operating system, the cap will never need to function. It's why it's a good PM item when doing other cooling system work. 'Cause you really want it to operate correctly.

Both are fine.

Frankly I'd just put the cap on a drive it a few short trips, enough to get to operating temperature, then a little more. When it cools off, open the radiator and add coolant if needed. IF there is any air stuck in the system, once it makes it to the radiator it will stay there, creating the space you top up.

I do have to admit though. In dozens of cooling systems I've worked on, I've never had to 'burp' anything. Even older Hondas that had bleeder valves. Just idling with the cap off, then the occasional short drive did it for me.

As far as running the heat goes, that's only a test. Several decades ago the systems eliminated the shut off valve for flow, and coolant circulates the core full time. Internal doors move when you select air flow to prevent that heat from coming in cab. Here in muggy-ville I've been known to add coolant bypass lines to improve AC efficiency.

 

Yeah im sure youre good to go. Bill is right, just drive it, that'll help burp the system best anyhow. I also have never had an issue burping the system on my rigs, very few bubbles if any at all. Keep in mind to have your heater valve open so water circulates through the heater core freely. Bottom hose will be the stiffer(both fairly stiff though) of the two usually when the system is pressurized since our trucks run the coolant backwards from most vehicles. Sounds like you got it no problem though, if it aint gettin over heated then its all good!

Also and this sounds weird but on the 3.4 the FSM calls for the tstat to be placed with the jiggle valve downward at the 6 o'clock position! Dont seem right but it is what it is. Its been documented on here and it actually makes like a 10 or so degree difference when placed with the jiggler valve up like you have it. @Dirty Pool knows the ins and outs of the 6 o'clock positioning incase no one believes me, wouldnt be the first time...


@Clearwater Bill our heating system has that valve on the middle of the fire wall in the engine bay that stops coolant flow. It dosent run through the core full time.

 

Well, shoot. I can't really afford to take the tstat out and rotate it as I have already poured all of the toyota coolant that I have into the system and don't really want to fork out the money to buy more. How detrimental do you think it would be if I left it in the 11 o'clock position?

Do you have some more concrete evidence that the 6 o'clock position is correct?

I appreciate the information, thanks!

 

Yep 6 o'clock. I did it 12 o'clock too and it was running at about 204-210. I turned it to 6 o'clock and it runs 186-192 now.

Not sure if it could be detrimental. But I would turn it anyways. You could just drain it as much as possible out of radiator, and reuse it since its all clean now. And will only lose a little when pulling the tstat. Then top off with distilled. Or just wait until you can afford to get more coolant. I don't think it will hurt. Just don't go on any long trips or tow anything and it should be fine until you get around to rotating that tstat.

 

Yip toendanger is right(thanks fur the backup lol. Was basically called a stupid dumbass a couple months ago by another member when i tried to tell a fella to run it @6 o'clock) and like i said earlier its in the FSM straight from Toyota, id post that from the FSM for ya but i dont have that available. But like toe said, you can run it like that for a bit itll just be running hotter than it should. He was over 15° hotter, thats quite a bit really. That would put the needle a bit higher fur sure. As far as coolant goes just catch it in a container and reuse, no biggie...

 

Here ya go.

 

Yep I think iirc my Haynes said to put it at 12. But I think I was reading the specs for the 3rz, that or it was just wrong. Can't remember.