6G Celicas Forums

Hi there! I have a 1994 celica ST. I put in a 3 core all alunimum radiator and my car started overheating. It was overheating from air being in the system. I blead it out (as far as i know) and my over heating went away. now i dont have any heat coming out of my heater. I only get warm air. my inlet hose going to the heater core is hot and my outlet hose coming from the heater core is warm but no where near hot much like the air coming out of my vents. I pulled off the in let hose and verified that the heater valve was working and it is. I took off the outlet hose and stuck my garden hose into the inlet side for the heater core and turned it on full blast, there was great water flow going through it. Then I checked the blender door by change the heat to cool very quickly and heard the blender door opening and closing. My coolant was topped off as well. The only thing i can think of is air being in the heater core. I jacked up the front of the car and let the air bleed out. I think this is the correct way to bleed out a system.

This post has been edited by rapid36: Jan 13, 2015 - 10:07 PM

Try using a spill free funnel or something similar to bleed the cooling system. You need to get the top point of coolant above the highest point in the cooling system. Jacking it up helps but I don't think it was enough.

Hey thanks! I order one and should have it in by tomorrow or the next day. I will keep you all posted! Thank you for the recommendation! Out of curiosity do these spill free funnels really make that much of a difference when bleeding air from cooling systems? I saw a ton of people on YouTube say that it works the best. Just curious if this worked as great as they claimed.

It's the second best tool I've seen to bleed a cooking system. I use mine all the time it hold enough and raises the coolant high enough on every car I've worked on. The best I've seen was a vacuum bleeder. It used shop air to suck out the air in the system then sucked in the coolant making sure there was no air.

also need to make sure the bleeder nipple on the thermostat is on the top side, or else it won't bleed correctly.
squeezing the radiator pipes repeatedly also helps push the air out.

After making sure it's been bled properly and if there still isn't any heat look at the radiator cap.

Hmm well i bled the cooling system and there were just a few bubbles not too much coming out. This didn't fix my no heat through heater issue. I'm starting to think if something is wrong with my heater core. I checked it and ran water through it just fine but I don't know why else why i wouldn't be getting any heat. So here's something interesting that i discovered. If i let the car run without turning on the fans inside the cabin then the outlet hose gets very hot much like the inlet hose, but after i turn on the cabin fans then the hose goes warm again, really strange. I checked the radiator cap and it was brand new, it came with the radiator and have a .1 bar more psi then the factory cap did so i would think pressure is fine cause of the fact that my heater worked before and plus i don't think this will effect pressure in the system until the thermostat opens up (correct me if I'm wrong). I'm completely lost at this point. Anyone got any more ideas based on what i discovered or ideas in general? You guys have been such a great helps so far and i thank you dearly!

FYI: When i was bleeding the air out i took all of your considerations and did all of them. I was squeezing the hoses constantly (both inlet and out let heater hoses. And also inlet and outlet hoses for the radiator.) while also using the spill free funnel.

This post has been edited by rapid36: Jan 9, 2015 - 5:23 PM

It's just odd that the heater core would suddenly die after changing out the radiator. Being turning on the blower motor makes a difference that makes me think the heater core is still fine. The cap maintains and allows the buildup of pressure. If you bought an eBay radiator, which it sounds like, the cheap cap probably isn't any good. Go down to the local parts store and get a Stant cap for it.

Also another thing, how much coolant to water are you running?

LOL!!! Yes you are exactly right its a cheap ebay radiator. And im very sorry if i wasnt clear before but what happened is that i changed out the radiator and i still had heat but i was also having an overheating issue. I fixed the overheating issue by bleeding out the air in the cooling system. At that exact point i lost heat in the cabin. So out of curiosity does the cap affect the pressure of the system even when the thermostat is closed? Also i will take a picture for you of my cap. Not sure if it helps but the more information you guys have the better. And I would of re-used my old cap from the original radiator that blew but the cap is smaller and doesnt fit. But since that i had heat before when it was overheating wouldnt that mean that i have a good radiator cap and that there is a good amount of pressure in the system?

I poured in 50/50 all the way. so i should have 50% coolant and 50% water throughout my entire system.

This post has been edited by rapid36: Jan 9, 2015 - 5:51 PM

The OEM radiator is notorious for cracking and failing, especially since they're so old now. Taking a picture of the cap won't make a difference, one can look perfectly fine but it'll be defective. And yes the cap works at all times. Also air pockets will cause a false read on the coolant gauges. Well if the OEM cap doesn't fit I guess you're stuck with what you have. One way to test the cap is let the car run and warm up, and carefully go to remove the cap. If nothing happens it's bad, if it starts to spew it's good.

This post has been edited by Box: Jan 9, 2015 - 6:08 PM

Hey thanks for the information! I was just indicating that the stock one doesnt fit this radiator (just in case if someone was gonna say JUST USE YOUR OLD CAP STUPID!) lol anyways. Im sure i can go to the autoparts store and find a cap that will work im sure they are standard sizes and im sure at least one other car has to have the same opening as this radiator. I really appreciate all of your information! I dont want to open the cap when the car is hot so ill just run by the auto parts store tomorrow and pick up a cap that will fit. Thanks and ill keep everyone updated!

I was going to say use a towel to protect yourself, if you place pressure onto the cap and untwist it slowly you'd be ok. Look for a Stant cap with the pressure release vent, not too much more than a regular cap and it's nice to have the ability to safely depressurize the cooling system.

This post has been edited by Box: Jan 9, 2015 - 6:36 PM

Ok thanks will do!

K did the pressure test by taking off the cap. its verified. coolant went everywhere. So it seems to be holding pressure. im not sure if its holding enough pressure but it is holding pressure.

Silly question, but did you replace the thermostat as well?

I know you said something about the inlet and outlet hoses earlier, and it'd make since with the blower motor reducing the temperature. Thermostat is only a few dollars and easy enough to replace. Again I'd go with Stant.

Yeah i checked the thermostat and replaced with another for grins and it did nothing. I put it in a pot with boiling water and a temperature sensor and it opened up at the correct time. However i have a question. The stock cap and in the book it says that this car should be at 13psi. The cap that came with the radiator is rated at 16psi. could this affect the no heat situation by having too much pressure?

It wouldn't decrease heat, if anything it'd make it hotter. The higher the pressure the higher the coolant can get before it boils. From what I found the SAE range is from 12-16 psi, so you're ok.

oh ok nice. I just got done flushing the heater core again and there is water flow, i dont have great pressure to begin with but it did flow as good as the hose did. and i still dont have any heat. it doesnt make sense. its really frustrating me. and you guys are so kind to help me so thank you very much.

The coolant system won't bleed itself the way it should unless you've got a Toyota radiator cap. It needs to both hold pressure and have a vacuum release to pull coolant back from the overflow bottle and I think most of the aftermarket ones don't have the vacuum part working.
Also I park it with the nose slightly uphill and let it run a while with the cap off so that the air bubbles can work their way up to the radiator.