I have read a few articles on burping the cooling system after you have drained it and put in new fluid. I tried it this past Sunday and I couldn't get it to work. I let the engine idle for at least 10 min and nothing was happening. I then noticed that the coolant level was rising pretty fast so I put the rad cap on quick and called it good. Now my car is making some really funny and loud noises and I'm pretty sure it's the cooling system. I'm guessing it's because there is a considerable amount of air trapped in there.

Would drilling a hole in the T-stat help this? I was also wondering if the overfill resevior could be letting in air. On the top of the overfill tank I have some kind of plug that is vented. Should I put a real plug in? Oh and I also have disconnected the heater box and have done the bypass deal with the water pump to the t-stat housing, if that matters.

 

the radiator cap is usually the highest point in the system on early mustangs so its not normally a big issue.

if i understand correctly you have an overflow tank instead of excess to ground?
If thats the case are you using a recovery type radiator cap? Still 13lb?

if there was coolant rising rapidly, there may be a big air bubble under there. Mine did that once and spewed coolant everywhere.

the solution was to run it with the cap tightened on and for long enough for the thermo to fully open and then let it cool for an hour. Top up if required.

Sometimes idling for 10 mins isnt enough. You can drive it around the block a few times just keep an eye on the gauge.

 

You are correct, I have an overflow tank and not the access to the ground (what were they thinking back then anyways) and I also have the 13lbs cap. Do I need a different cap? Well funny story, I stripped the aftermarket sender that goes into the intake manifold so I actually have no temp guage right now, but I know it never gets over 180 in any situation.

 

yes, the "recovery" cap is slightly different. It has a secondary rubber seal arrangement.
the standard cap will allow water out but not back in from the overflow tank.

 

hmmm i think I do have the recovery cap because I have seen fluid enter and exit the overflow just fine, I think.

 

don't drill.
don't you have a bleeder hole that can be opened with an allen key just behind the thermostat?
I have one, so I assume ...

and yes, if it's burping especially shortly after you switch off engine, then you have air trapped

 

I've never seen that allen head hole before. probably because we have different intakes.

 

actually you're right. not on the intake. I have it on the thermostat housing. Sorry.
Check this picture:

right between the petrol hose and the vacuum advance hose

 

kalli you shouldntuse that
the air rises to the highest point eventually...the cap.

 

i see duct tape on the dizzy in that pic?