vetteguy75

What is the best way to "burp" the cooling system? This past weekend I changed the coolant & thermostat. Here's what I did...

1) filled the radiator to the neck with 50/50 coolant.
2) fired up the engine
3) waited for the coolant in the radiator to drop (indicating the thermostat was open and the coolant circulating)
4) while the engine was running, filled the radiator back up with coolant/water mix
5) replaced the cap.
6) made sure there was coolant in the overflow tank.

did I get the air out?

Jud Chapin

I would say yes. How's the temp? Actually, I think there is way too much discussion regarding air in the system. I've been flushing and refilling systems for over 40 years and have never had an air issue.

wfo76

I have had air issues before and they will eventually work themselves out. When refilling the cooling system, I like to fill the engine thru the thermostat opening, install the stat and then the top off the rad. When you say you filled with 50/50 mixture, there is coolant still remaining in the block and heater core or straight water if you flushed it first. If you had straight water in the system, you now have a weak mixture that is less than 50/50. Best way to do it is to flush the system and drain the rad. Jack up the rear to get as much water out as possible or use compressed air to blow some more out. Then look at your cooling system capacity and add exactly 50% straight coolant to the system. When everything mixes, you will have a 50/50% mix.

Wrencher

Here's another helpful trick I use on most engines. Look at the thermostat before you install it. All the older cars and some new 'stats had a small hole in them off to the side with a tiny brass float. This allowed air in the block and heads to vent as you filled up the system. Most replacement 'stats don't have this, so I drill a 1/8 hole in the flange to accomplish the same thing. Now you can fill it and not worry about it. Also on some cars that have a low radiator, I'll jack up the front of the car to make the filler the highest part of the cooling system. Works like a charm. Always recheck the level after it cools off.

Hans

Stroker-427

Drill a small hole (1/8") in the thermostat flange...... and forgot the problem!


..just my two cents!

Jud Chapin

AS I mentioned above, I've never had an air issue. For those that have, I'm curious as to how you determine that air is in the system.

S489

if you fill the system, run it to temp so that stat opens, then shut it down, the coolant should then expand into the overflow tank (for those year models). at this point, sqeeze the top rad hose, forcing air out of the system into the overflow. you can see the air bubbles. when most or all of the air is out, ya can't do this . . .

rihwoods

I always elevate front of vette on jackstands when flushing/adding new coolant...this equalizes rad cap/thermostat height to minimize air in system...

wfo76

Jud, the time I think I had air in my system the temp gauge would start to peg like it was going to overheat, then it would suddenly drop to normal then it would start climbing again. Just really screwy readings from the temp gauge. Somebody at the time told me about an air pocket so I pulled the stat out and filled the block. Left the stat out and filled the rad until the block stayed full, put it back together and the gauge read normally after that. So not totally positive it was air, but it seems like that's all it could have been.

bytor

This works and is a neat effectiveway to purge the air out of you cooling system. http://www.allhead.com.au/cooling.html

69/03vette

Boy I sure hope you can help me. My water jacket on my intake is higher than my water level in my expansion tank. This creates an air pocket in my intake (removed the thermostat housing without draining the radiator to prove this and my inkate had no water in it) If I fill the expansion tank to prevent this then coolant blows out the overflow tube. Sorry for hijacking this thread but this is driving me crazy.

Jud Chapin

Thanks a lot for the info.

Vette Gator

I bought this funnel for my C4, which can even more challenging to burp. The reservoir is above the highest point on the motor, and the plug lets you remove it without spilling coolant all over the place. The 1/8" hole drilled in the T-stat was also a big help, as already mentioned.

http://www.denlorstools.com/home/dt1...fill_adap.html

S489

in the video the guy still used his hand to squeeze the top hose . . .
i would like the bleeder valve, but mounted as high as possible

bumpervetteman

In the past any time I did radiator or coolant work; I filled the radiator to the top and cranked up the engine when I seen the fluid drop
( thermostat open) I then topped off the radiator, right at the point of it spilling over I put the cap on and called it good. From there I let it pressurize by checking the upper hose and monitor the temp. After it cooled I opened the cap to ensure the radiator was full. ALL DONE