[65vert]

I've read many threads/discussions re overheating and am hoping there is a "silver bullet" that I'm missing. I want to avoid at all costs putting on an electric fan since I believe there must be alternatives I'm just not seeing. Prior to having the engine re-built, the car was fine - even with the A/C on in the Summer it got warm, but never threw any fluid or got as hot as it is now.

Now I've got about 800 miles on the new engine which was rebuilt and bored out to a 302 plus a 4-barrel carb.; has A/C and a shroud; new over-sized 2-row alum. radiator w/ 13 lb cap and filled w/ water wetter; timing has been checked by shop and is ok; cooling system has been tested and no leaks.

When driving above 30-35 mph the cooling is fine (on the "E" in TEMP); however if I idle for more than 20 or so minutes - or stop/go driving, the temp runs up to and past the "M" and "P" and the idle drops and the car almost dies (I put it in Park to keep the idle up). The temp gets up to 240.

I've tried to see if the head gasket is on wrong and can't locate two square pieces of gasket that are supposed to be sticking out from the front of the head? I'm thinking that if it cools at 35 mph and above it's not the head gasket. Is there anything else that tells me it's on right - or wrong? Want to avoid pulling the head and spending any more $$$ just to check.

I've also recently run it for 40 min. or so to get any air out of the system.

I'm replacing the shroud w/ a larger fiberglass one that has less gaps/spaces so that should help suction - am also thinking of putting on a 16 lb radiator cap. Am also going to put a smaller fan spacer so that it will push the fan out from the radiator, and be 1/2 way into the shroud - have heard that might help.

It has an overflow tank that collects any overflow - which it does some of the time.

I've also installed a shutoff valve on the hose going to the heater to keep more fluid in the engine.

Welcoming any thoughts - suggestions.

[nigel]

Welcome to the site. Try water wetter at advance auto. Dropped my tem by 15 to 20 degrees.

[65vert]

already added water wetter - still hot.

[PaulS]

If it overheats only when idling then you need more air flow at an idle. bigger fan, more blades or a better fitting shroud. You might be able to cool it by hooking the vacuum advance to manifold vacuum instead of ported vacuum.

[65vert]

Thanks PaulS. I've got a six-blade fan already - is there a larger one? As I mentioned I'm going to install a 3 1/2" fiberglass shroud that's supposed to help - as well as back the fan out a bit more so it's 1/2 way inside, and not all of the way in. Am hoping these "small" things add up to help out.

Haven't thought about your vacuum suggestion - what are the down sides - performance?

Thanks again.

[65vert]

One more thought - I've put water wetter in the radiator, but has anyone tried an anti-freeze type I've heard about that's incredibly expensive but is supposed to work? About $60/gal. but all the ads say it works....

[65vert]

Just went out with the car for about 15 minutes. When I came back and turned it off (no overheating) there was a low "thump" that came from the engine, about 5 or so seconds apart - it kept on doing it for about one or two minutes - very strange. After thinking about it I think this same thing has happened while the car has been running, but this is the first time I've heard it clearly - since the car was off. It clearly was comming from the engine, and I couldn't tell if it was a liquid sound or something else. Crazy? Connected to the overheating problem.

Thanks for any thoughts on this.

[fonzoayala88]

is it a ticking noise? my car always makes a ticking noise after i turn it off and it was running hot. im pretty sure all cars do that, i guess its like the headers contracting, seein how they expand when hot.

[1967_Red_Stang]

This may not be related to your problem, but my 302 was overheating on the highway and I put in a spring in the lower hose. That solved the problem. Your problem is related to low air flow or radiator low cooling capacity. Did you try to remove the AC radiator or inspect if it is blocking airflow. Is it an original AC or retrofit?

[RF Mustang]

Like the guy said earlier, check your hose to make sure it has a spring so it does not colapse. Paul S is right, you need air flow but your vacuum may also be an issue.

are you sure your timing is right ? If your timing is advance, it will definately make it run much hotter.

You have to keep in mind, when these cars were first built. These issues were not so common so you have to think something logical is going on.

I disconnected my heater hoses period and just ran a bypass hose. a 2 core aluminuim radiator and it never gets past a quarter of the way.