[Bob ONeill]

I don't want to say 'never' but..... you'll never get that out.

Instead pull the thermostat housing and drill a 1/16" hole in the rim of the thermostat above the 'workings'. In this way as you fill the radiator the air will flow through the hole. Then raise the radiator cap higher than the thermostat and fill it with the cap off. Crank the car and let it warm up and keep filling as the level falls. As the thermostat opens it will start to flow. With the system 'full' turn off the engine and top off the radiator, replace the cap and fill the overflow tank about half way.

The system is not burped.

[bamman]

It's a 5/16" allen wrench. It's like the only thing that is not metric on these cars.

As for never getting it off, I broke a couple of my neighbor's allen wrenches trying to get the plug off. It helps if you have a metal pipe to use as a breaker bar to loosen it up. If you do get it off make sure you apply Teflon tape to it.

As for my plug, I've replaced it with a brass one with a square head so I can use a wrench on it.

[Bob ONeill]

There is no reason to remove it, really.

Just drill the hole in the thermostat. In the long run it's far easier and the other benefits are substantial.

For example......

As the head heats up coolant will flow through that tiny hole which (believe it or not) will reduce the stress on the head when the thermostat finally opens as a tiny bit of hot coolant flows through during warm up.

Also it's guaranteed to properly burp the air out of the system.

[Abkshelby]

Bob ONeill, on Apr 20 2009, 08:52 PM, said:

There is no reason to remove it, really.

Just drill the hole in the thermostat. In the long run it's far easier and the other benefits are substantial.

For example......

As the head heats up coolant will flow through that tiny hole which (believe it or not) will reduce the stress on the head when the thermostat finally opens as a tiny bit of hot coolant flows through during warm up.

Also it's guaranteed to properly burp the air out of the system.

I learned this the hard way on my original '86 GLHS way back in the early 90's.
The plug seized in that head and I had to drill it out.
I started drilling the hole in the thermostat at that time and have never tried to remove the plug in any other head.
Just leave the plug in there and drill the thermostat. Works great.

[Bob ONeill]

The straight up position is best.

[Bob Lincoln]

If you were a registered user, you would not be seeing this!

I have never had to drill a hole in a thermostat, and never had trapped air. Just park the car uphill and run it with the cap off and heater on, and the air will bleed out.

Vaporlock is a stallout condition from fuel vaporizing and not flowing in an liquid state. You have no vaporization of coolant here, it's trapped air.

I tried removing that plug the day after I bought my car new. No go. Don't even bother. Not worth creating a leak that will need aluminum welding.

[soloflite]

Also could be you just need to drive it up the street and back. the last two times I flushed my system, I refilled w/ the engine up and still wouldn't burp. put it in gear and moved it down the street and back and BELCH.. All cleared up.

[toddsturbo]

i've never had to do any of this.i just start up my tona,pop the cap off and fill til it's full.then fill the overflow halfway.the previous owner had replaced the radiator and the fill hole sits higher than the waterbox.am i understanding correctly that the original radiators sit a tad lower than the waterbox thus trapping some air?either way i've never had any issues.