does anyone have a return from the overlfow to there radiator?  I don't have a stock TGP radiator anymore and I forgot if there was a return on it.  I keep getting air in my cooling system and can't figure out why.  The hoses aren't leaking and are tight.  I can honestly remember the stock radiator having a little nipple on the top that went to the top of the over flow but the bottom section just running off to the bottom of the car.  On every other GM 4/6 the overflow runs in a circle back into the radiator or water pump.  I am trying to track down why I have to keep venting air from the petcock vavles.

No,

The tank is not part of the pressure system on a TGP, and its that way on a lot of cars.

The cap on a cooling system allows fluid to be sucked back in when in cools. As long as there is coolant in the overflow that part should be fine.

There will always be some air that settles to the top, but when the coolant flows again it will move. Bleeding the system forces an airlock out of the coolant system.

I keep getting big time air lock and can't figure it out.  I stopped to get gas this morning and turned the thermo screw and it was straight coolant.  I turned the other petcock at the wp and it hissed for like ever but i had to get on the road so I know it was more air in there.  I am trying to figure out where its coming from.

Is it over heating?

its weird as hell when i drive like at 60-95+<-----:> the temp needle goes up and up.  when i sit in traffic its stays 1 notch below the mid mark WTF!

check for a leak around the oil pump drive, my lower intake gasket was slightly blown in that area causing a small leak and air in the system accompanied by running hotter than usual..needless to say, fixed it asap and no more problems.(this was on my NA 3.1 w/ high mileage)...btw, are you loosing any coolant at all that you can tell?

no coolant loss! its freakin wierd, as you increase speed the air absolutely has to blow faster and cool the radiator.  for some damn reason the temp goes up I don't freaking get it.  But in heavy traffic the fans kick on and its stays below half.  Did you hear a hisssss under your upper manifold when the engine was hot but not running???  I am going to remove every DAMN hose on that car and see what the heck is going on.  The only other thing is maybe STOCK from 90 <-----WP is clogged to hell or something.

yeah, I heard a hissing(like air)  followed by a gurlging water/coolant sound under the intake mani....

Or your theromostat is stuck partially open, so it moves enough water at slow speeds, but doesn't open enough at higher speeds.

think so!  well its off to try that. ty

no gurgling and no coolant loss. just a hiss.

Oh, and I meant to add that the "air" probably comes from the water backing up the wrong way if it overheats and even boiling creating steam.

Just a shot at this...but could it be that the temp goes up cuz the fans turn off at high speeds and there's isn't enough air that goes thrugh the radiator...prob from the fans you got. Could it be that the trans is getting too hot(OD) and cousing the coolant to heat up more. Maybe the hoses are calapsing. Its strange..the car should run cooler at speeds than on stop and go traffic.

Thats why it has to be a coolant flow problem, not an air flow problem.

Even if the fans are running or not running at speed, it won't block the airflow from the car moving. If not enough coolant is flowing though, it can cause these problems. THe hoses sucking shut is a good point. But I'm pretty sure the lower hose has a metal coil in it to keep it from sucking shut. This would be the only one that is likely to suck shut. The upper hose is on the outbound side of the water pump so it shouldn't suck closed.

You're right the car should run cooler, but if its making more heat from the larger load of moving down the road then it won't. Unless the radiator isn't up to the job of cooling the car (which I doubt), he shouldn't have a problem.

raditator is an aluminum griff unit,  I think the thermostat is not opening all the way like you said.  I am gong to get one today.