It's a test you can do even with a cold engine, if the thermostat is out. You just have to be sure the cooling system is full.
Start the engine and look in the radiator for small bubbles, maybe the size of a marble, give or take.
Good luck.

 

How do I know if the cooling system is full?

 

When the engine's running and the radiator is full? lol
I'm not trying to be condescending or anything so don't take it that way, okay?

 

This happens 2-3 times when I change the coolant or thermostat.

Here's how I burp my cooling system for the last 15 years without any problems:

Park truck on an incline facing upward

Remove radiator cap and start truck

Let the truck idle until the thermostat opens

Once the thermostat opens, rev the engine to 2000 RPM's for an additional 10-15 minutes (no, I'm not exaggerating!).

Don't shut off the engine when the radiator geysers, keep it running. If the coolant disappears from the radiator, add more 50/50 coolant/water and continue revving engine.

 

Thanks! I thought that if it gushed out there would be more bubbles still in the system from just gushing out. I am going to try that tomorrow...thanks for your help!!!

 

i got a v6 and mine had the same problem so i took the heads off after a compression test and i had a cracked valve. got it fixed and workls fine

 

I don't have a cracked valve though...

 

Yeah I know. Its kind of a dumb question...but I meant like how do I know if it is full and no air pockets? Its obviously easy to visually see if it is full but I really don't know if it is completely full without air in the system.

 

Did you try removing the t-stat and filling the block as I suggested, followed bytopping off the radiator and letting it run with the cap off for 10 minutes or so. That procedure should remove any air trapped in the system. If you are still overheating then your problems are else where.

How many times have you burped the cooling system now?

 

Right now is my second time. I burped it using antifreeze the first time then I just used water...as I am sick of buying antifreeze.

It still overheats and I took some pics. It does not bubble like someone said but the water goes up and down due to the engine constantly surging. I am getting to the point of giving up.

If I take the thermostat off and fill the block it is already full. Are you talking about draining the system then fill the block up???

 

IMO, I would start all over, and for the sake of the environment, re-use the coolant you just bought.

Drain the system and close the drain cock, remove the t-stat and pour your anti-freeze solution directly into the block until it's full, and re-install the t-stat and housing, re-fill the radiator and leave the radiator cap off. Start the engine and let it idle, don't rev it up. Turn the heat on in the cab and wait 5-10 minutes. Add coolant to the radiator as the level dops and air is purged. Put the cap back on and drive it.

 

Thanks mr_schuster! I did what you said but with water. I did not reuse my antifreeze because it has a bunch of dirt in the container I put it in and for the sake of my already crappy engine...I don't want to up the water pump too.

So, I was doing what you said and I decided to use some wd-40 on the lines. I started spraying some on the lines and my engine almost died. I then went inside to tell my bro the news and came back out and my truck ran out of gas. I looked at my vacuum lines and found a small line that had a hole right in it. I hope that is my problem. I ran out of gas so I am going to continue burping it with water then fix that vacuum line. Thanks a bunch guys...and a HUGE thanks to Abecedarian!!!!!!!!!!!!!!!

 

O.K, my truck has been running for 20 minutes and has not burped yet...or maybe the thermostat is just a piece of !!! I don't know. I am thinking about buying the dual stage thermostat though. It still doesn't explain my ing idle. I sprayed a hell of a lot of wd-40 on the vacuum lines and no difference. I even took of a vacuum line on the intake and no difference...wtf??? What the hell is wrong???

 

O.K, I think the thermostat needs to be replaced with the dual thermostat one because mine is always fluctuating.

Somehow I fixed my idle...it must of been the two jumps and several 6k rpm runs...lol. Anyway...it will start idling like at 1700 then I will rev it to 5k or so a couple of times and it will die down...wtf???

 

Fixed!!! (I think!)

Anyway, I took out my thermostat and drilled two holes on each side. My truck only goes a partial way up but my heat is hot like normal and it doesn't over heat. I am going to put some antifreeze in it now. My idle is perfect and I have no complaints! It runs like a top! I don't know why my idle was screwed up...but when I rap the out of it when it starts acting funny it goes back to normal (only happened twice so far....but who cares!)

Thanks guys....if I have any other problems I will be back.

If any of you have any questions feel free to reply

 

Coolant temp issues can affect idling due to the coolant sensors, switches, and valves that operate according to temp.

But, it sounds like something is sticking. Reason being, your rapping changes it. What exactly are you hitting on?

 

Yeah...I thought so too. But when my truck was over heating it would idle like at 1700rpm ALL the time. Something probably is sticking...not sure what it is. Is the dash pot supposed to be touching something? What do you mean hitting on???

 

oohh....bummer. #3 is where your gasket is blown.

 

Yer all nutz. 91toyota, you've got a blown head gasket. I had all of the same issues including the crazy idle surging. At 1st, mine would only surge when I'd touch the brakes with the a/c on,...then it started doing it as soon as it'd warm up without the brakes being touched. It would get hot as hell too when it surged at idle, so I replaced the whole cooling system. Needless to say, it would still get hot. This is when I noticed it was the head gasket. The 3 rear cylinders had coolant in em. And for deserthound,.... How could you not notice your timing chain grinding thru your guides into your cover?!?! It makes a horrible rattling sound as if you've got 100 BB's bouncing around in your engine. You should've noticed this since you say you hear any weird noise that's coming from your purring kitten.

 

I only put about 3500 miles on this engine since I got it and no, it did not make any "horrible rattling sound". It ran better than my '89. Since there were no pieces of the guides in the cover or the oil pan, most likely the previous owner decided to just button it back up.