Air in the System

What is the best way to check for and then possibly get rid of air in the cooling system? I installed a new radiator a couple days ago and want to bleed the air out of the system if possible.

I have been told to pull the upper hose that goes to the heater core to check if it is full, then to add appropriately. Is there any other way or anythign else that I can do? I have serached the threads, while there is a lot of information overheating, nothing that I can find on air in the cooling system.

I just installed a heat buster 3 core radiator, changed the thermostat, checked the clutch fan, water pump, electric fan, and am still heating up to 215/220 with the AC on when I pull off the freeway or to a stop light.............the madness has to stop somewhere!!!!

Thanks,

(shaking head) - 215/220 is normal. I'ts slightly to the high side of normal, but it's still there. Did your thermosat have a check valve or bleed hole in it when you installed that, and is it at the top? The hole in the thermostat helps prevent air from getting trapped on one side. Burping methods vary, but with a 2000 most folks will tell you to remove the upper radiator hose and make sure it's full, I found that parking nose high seemed to help when refilling mine. That would be nose low on the old 87-90 versions with the screwed up recovery tank at the rear of the engine bay.

Is your electric fan working ?? Theorhetically you'd think a 3 core would cool better than a 2 core... But it ISN'T always the case...

Yes, the electrical fan is turning on around 220 or so which is where it should be turning on I guess. I am now considering wiring the fan to a toggle switch.

That is a good idea on parking up hill. I will try that.

The accepted way to burp the head is to park it downhill and using a 1/2" deep socket, loosen the temp sensor on the rear of the head on the driver's side, until fluid starts to come out and then tighten it back down. Do this with a cool engine.

A cooling system on a 2000 shouldn't require burping. Heat Buster radiator? where did you pick that up at? What temp thermostat did you install? Did you check it before you installed it? 215-220 isn't bad, does it ever go higher?

Are you filling throught the radiator? After a run and it cools off, do you constantly have to add coolant/water to it?

Best way to burp the system, nose up hill a bit, remove the rad filler cap, run engine, top off filler with coolant, look at coolant, if it's fizzy like green soda you have air in it, let it run and keep the coolant topped off till there are no more fizzys. You will notice that if you blip the throttle the coolant will go down alot in the filler neck, in a coordinated manner, blip the throttle, top it off while the level is down and quickly put the pressure cap back on. It generally takes about 30 min to do it right from cold....
Also pay close attention to the mention of the little bleed valve on the tstat, if yours did not have one or you did not put in the 12 O'Clock postion you have a 'do over' and need to fix that first.

You don't even need to go through a process as complicated as that. First step is to make sure the radiator is full of coolant and the expansion bottle also has coolant up to the "full" mark. Park the vehicle on a hill with the nose facing upwards and start the engine. Switch on the heater and let the engine idle for several minutes. You can step lightly on the throttle and raise the idle rpm to quicken the process. Once the engine's up to 210*, switch it off and leave the vehicle parked nose up. Allow the engine to cool down completely. By then, the coolant level in the radiator would have dropped a bit and most of the coolant in the expansion bottle will get sucked back into the radiator to replenish it. All you'll have to do then is check the coolant level in the expansion bottle and top it up. You might need to check it a couple more times just to make sure it doesn't drop again.

Only problem with that is that when you have a really gross amount of air in the system it becomes air bound and the air gets suspended in the coolant just like carbonated soda, the water pump will also cavitate remixing air and coolant. The down side is that with the tanks on the sides the air does not 'sit on top' like it does with a top/bottom tank design like the TJ's have, result is the side tank design are a natural aerator and will remix the air as the coolant is forced thru the coolant tubes and jets out into the other side of the tank which supplies the pump so the air/coolant just keeps getting pushed thru again and again. Just like carbonated soda it will 'go flat' after a few days as long as you keep adding coolant into the radiator filler neck, displacing air and eventually go into it's normal cycle. My way it gets the major air out and over the years I've found out what works for me. I've always needed my wheels for work so minimal downtime and good repairs are a requirement as well as dependability, one of the reasons I will replace a radiator, hoses and belt if I do a water pump as long as I have the whole thing apart anyway.
That said I now have access to a coolant machine that draws a vacumn and refills the system with air free coolant, drains and refills in about 20 min with no muss no fuss. I sure wish someone would come out with a cheaper version [less than $200] that I could buy for the house though.....

I know that some years had a closed system and some had an open system, which system needs burping and what years?

Robert

Alright, I attempted to burp the system last night, and it seemed to run a little cooler, then again it was only 80 degrees outside. When I changed the thermostat I put a superstat 180 in and drilled a 1/8 hole at the 12 o'clock position. I am going to take it out on the freeway and maybe up the canyon to push it a little today. After I take it out I have had to add a little coolant, but not much.

My fan was also kicking on and off with the A/C blasting as early as 210, I am assuming that this is pretty normal. Have any of you bypassed the automatic setting and just wired it so that it is either on all the time or attached a toggle to it? I know that Mbryson has done this, and kicks his on at 180 on the trail.

Do you think that my larger tires and changed gears could have anything to do with it also? I mean the speedometer is WAY off right now, when it reads 80 I am actually going 66......would adding one of those truspeed speedometers help any? My YJ was a lot more simple.

Thanks,

ewander said:

Do you think that my larger tires and changed gears could have anything to do with it also? I mean the speedometer is WAY off right now, when it reads 80 I am actually going 66......would adding one of those truspeed speedometers help any? My YJ was a lot more simple.

Click to expand...

Just put a 39-tooth speedo gear in the t-case output and call it good. $20 or so at the dealer vs how much for the truspeed doodad?

one good way to get air out of the cooling system is to remove the heater hose from the thermostat housing,then fill the system, when the coolant runs out, the block is full. then top off the radiator. works well on the older style cooling systems also.

If Dr. Dyno's procedure doesn't burp your system, I don't know what will. My 2001 burps itself (it's about the only thing it does right). If yours keeps pulling air in, it probably has a leak. Check where the engine may pull air in. Where coolant goes into the engine, that is. The whole engine pulls coolant until it hits the pump that pushes it back to the radiator. That includes the heater
You can always pull the hose that goes from the thermostat to the radiator and let the air out (engine off); but, since you already drilled a hole in the thermo, that won't be much better than opening the radiator cap.
210deg doesn't seem too high. Does it go much above that?. Since the thermostat won't let the temp drop, don't worry unless it goes above 5/8ths of your gauge. Also, you can change to a 160deg (summer) thermostat and let the temp drop a little; but don't expect much.
If this doesn't work, and assuming your water pump, radiator and thermostat are OK and your engine is clean inside, then your RPM are way too high and the cooling system has to be enhanced by installing a better radiator and/or water pump (Which you already did. Gear/tire ratio, as you comment, has an effect in your need for heat dissipation.
Follow Yucca-man regarding the speedometer.
Talyn's questions are key to all this. Maybe you're being overfussy. Does your temp frequently go above 5/8ths of the gauge's scale?

Okay, I burped the system, pushed it pretty hard going up to the Sundance Ski Resort and over the Alpine loop. It did pretty good, never getting above 220. When I got home I noticed that my thermostat gasket did have a leak (possibly pulling air into the sytem). I changed the gasket enlarged the hole that I had previously drilled a little in the thermostat and reburped the system. On the freeway it ran just under 210 or right on 210, in the slow and go and then on the trail it ran about 215, which according to this board is close enough for government work. I then pulled a trailer to the land fill and it still didn't get about 215-217. I think I am calling it good. It was 98 degrees here today, I had the A/C blasting when I wasn't wheeling, so that just has to be good enough.

Thanks for all of your help. I was getting a little paranoid because I will be making the drive from Utah to California and then doing the Rubicon and possibly another trail close by in a week and a half.

Thanks a million for all of your help.

I don't think the superstat needs the hole, as it's new "v" technology takes care of that for you.....