1988 Overheating Issue

I have a 1988 305 5 li Camaro. For some reason she constantly heats up, pretty quick too. I can drive her around for a good 10-15 minutes before she's in the red, but after that I have to let her cool for a good several hours before being able to drive her safely again.

So far this is what I've done...

Replaced thermastat (3 times)
Replaced Water Outlet (thermastat housing)
Replaced Water Pump
Replaced Hose lines
Changed Electric Fan to a regular engine Fan.
Took Radiator to a Shop and they found no problems with it.
Checked the heads, they look fine, from what I can see.

And it's not the gauge, I wish it was. She visably overheats. I'm stuck. I'm about to get rid of her cause I can't figure out the problem:banghead: . I don't want to sell her, but I may have no choice.

It has an air damn on it correct? i only ask because one guy was having issues a while back and did not have one.

However, I would lean more towards the possibility that the water/coolant is not getting circulated through the system. Is it possilbe that there is a clog in the system somewhere? Are you absolutly sure that the water pump is moving water? I know you said you replaced it, I am just shooting out ideas right now.

When I look, with the cap off, I see the water/coolant flowing through. And I don't have the front ground effects air dam (if that matters). There might be a clog. I haven't done a complete flush yet. I might end up doing that payday if not sooner.

I am not sure that the air dam would cause this exact problem, but I would definately get one, they help get air to flow through your radiator. If you can see that the coolant is moving it probably is flowing through the system just fine. You might as well get an air dam check out a few salvage yards in your area you might be able to get one for pretty cheap and hopefully it will solve your problem.

Since you covered most of the external areas of the cooling system I would look into the internal engine components.The intake manifold/heads could be warped or the valves are out of adjustment.I even seen sludge build up towards the rear of the heads not letting the oil cool the rear cylinders.Your on the right track, you'll find it in the motor itself.

You went through alot of major players that could cause this problem, but one vital key one: radiator cap. Any time you replace the stat, replace the cap with one of a equal temp value. If the cap is no good, and does not hold pressure, then the boiling point is lowered dramatically.

Additionally for $2 get a hydrometer to check the protection value of the coolant mix (50/50).

And a air dam will make a difference