restoring

The issue: Insufficient Burping of cooling system

2001 XJ, new radiator about 2 years ago put in by a shop. Old radiator split a plastic end cap while away from home and couldn't tow the Jeep back to the house to do it myself. It appears they at least half-a$$ flushed the system when they put the new one in.

This past 2 weeks, I've been replacing transmission oil cooling lines that run from the transmission to the radiator (yes, 2 weeks. Check the end of my build thread for why it took so long).

One of these lines connects to the radiator immediately beneath the lower radiator hose. Try as I might, I could NOT get the disconnect tool to seat on the line without removing the lower radiator hose. Of course, this drained the radiator. No petcock valve that I could locate on the radiator either.

Transmission cooling lines finally replaced successfully, and radiator hose reconnected. Let the burping begin!

This is what I did:

Parked it in our driveway with the nose higher than the rear.

Removed the radiator cap.

Filled the radiator up to the top.

Filled the overflow bottle a little more than half way to the top.

Set the heater controls to maximum temperature and the fan to HIGH.

Started the Jeep and let it run.

As bubbles burped out through the radiator cap opening, I added water to fill it back up.

Kept repeating this process even after the heat had been blowing hot for a while.

Stopped when the system started pushing coolant out of the radiator cap opening.

Even after that, the top radiator hose feels like there is no coolant in it. The hose to too soft when squeezed for there to be anything other than air in it. This hose arcs UP from the radiator and rises higher than the top of the radiator itself. Try as I might, I have not figured out how to purge the air from that hose. Air rises and this is the highest point in the cooling system.

My uncle is know ALLOT about this kind of stuff and advised I close the system back up and drive around with an extra bottle of water, keeping an eye on the temperature gauge and the system should burp that hose out at some point. He said as long as there is sufficient coolant in the overflow bottle, the system will purge the air into that bottle and as it cools later, it will draw coolant back in. So far, not much driving around and have heard horror stories about hot spots, cracked heads, cavitating water pumps, etc.

Ideas/suggestions?

00t444e

Just drive it for awhile and keep checking it.

Ralph77

I agree with your uncle. I used to do it like you, but just level, until the coolant started bubbling out. Then drove it. Add coolant as necessary. About 3 days or so it is at the levels I wanted. But then I invested in the Lisle funnel.


Hook it all up. Do what you do with the heater and keep the engine at about 1500 RPM. Make sure there is always some coolant in the funnel. 1/2 hour, 45 minutes tops, later good to go. Since I dump my anti-freeze every 2 years I am so glad I invested in this tool. And once I get my Ext Idle switch hooked up will just use that to get the RPMs higher when doing it. Thinking 1000 RPM will be just fine. Maybe take a little longer. I am also wondering what condition is your radiator cap in?

Turbo X_J

"Burping" a cooling system is an old wives tale that pretty much ended with the demise of the Renault LeCar.

jordan96xj

You stopped before it really got to burp then. It was the moving/expanding air in the system that starts pushing that coolant out of the radiator cap. On mine, it usually does a bunch of small burps at first, but when it really starts to warm up, it usually has 1-2 large "heaves" that will try to blow a lot of fluid out of the radiator cap, then after these large air pockets get out, it is basically complete (very little air comes out after that). I use a Lisle no-drip funnel with some coolant in it, so that I don't have to close off the radiator until it is truly burped. Well worth having, and not very expensive.

firebane

Yup. Its going to burp over anytime you use it. These funnels work good:
Funnel:

jordan96xj

Exactly. Here is the one I have:They didn't have as many different brands of them when I got mine several years ago.

The first time I used it on the Jeep, I set it up like I had on my previous cars. With about half the funnel filled with coolant while the motor warmed up and burped. When the thermostat opened and the vehicle neared operating temperature, the coolant in the funnel was force right to the top of the funnel...and then BLAM! a huge slug of air blew almost the whole funnel's worth of fluid all over the inside of the engine compartment. I now know to only fill the funnel about 1/4 (at most) when I'm doing the Jeep. Even then sometimes the fluid will get near the top of the funnel as large blocks of air work their way out. I'm fairly certain it is when the thermostat opens and enough coolant is pushed through the system to begin pushing the massive air block that collects in the heater core (as it is the high point in the system).

tinytrax78

I use a vacula air lift

restoring

Thanks for the information! Can't invest in that funnel right now, but definitely want to get one as soon as I can.

WyoCherokee

It's gotta warm up past the Thermostat temp, and stay above thermostat temp in order for air to escape the system. You don't have a Renix closed System, so you don't need to "truly burp" the system. the over flow tank is vented to allow burped air to escape the cooling system. Drive it around, keeping an eye on coolant level and temp gauge for a week or so, and it will purge itself.

DFlintstone

Idk there Turbo. 87-90 Renix can and indeed do cause some headaches with trapped air in the system. Even with the hole correctly up at 12:00 on the T-stat, it can still be a bit dicy.