350 heating up really fast

Just installed this '71 350 in my '81 Cutlass. Started it up for the first time yesterday and realized the radiator had a good leak in it right in the middle and it's going to overheat if I let it run. New 195 thermostat in here too. So I start it up, car runs for about 3 minutes or so and then temp starts to climb pretty quick and will definitely overheat if I don't shut it off. Gets to 220 on my temp guage and water in overflow starts boiling so yes it's definitely getting too hot.
Would the leak in the radiator be causing the problem? We keep enough water in there even though it's slowly leaking.

Just installed this '71 350 in my '81 Cutlass. Started it up for the first time yesterday and realized the radiator had a good leak in it right in the middle and it's going to overheat if I let it run. New 195 thermostat in here too. So I start it up, car runs for about 3 minutes or so and then temp starts to climb pretty quick and will definitely overheat if I don't shut it off. Gets to 220 on my temp guage and water in overflow starts boiling so yes it's definitely getting too hot.
Would the leak in the radiator be causing the problem? We keep enough water in there even though it's slowly leaking.

At those temps the thermo should open and at least cool it down a little. You sure your water pump is circulating water?

At those temps the thermo should open and at least cool it down a little. You sure your water pump is circulating water?

Not sure. When we had the radiator cap off fluid started movin around and sloshing out. It's a new water pump.

Not that it's the issue but I assume the 71 engine has no ecu and sensors, so the 195 t'stat is wrong, should be 180, a bad head gasket can cause this as well as a water pump impeller, clogged radiator, wrong timing, fan clutch bad and so on.

A stat installed upside-down will also cause this.

A stat installed upside-down will also cause this.

I've got the stat in spring side down.

I've got the stat in spring side down.

I would pull the stat and see what happens. Been know to get a bad new one.

I would pull the stat and see what happens. Been know to get a bad new one.

One thing I don't understand with this Oldsmobile system compared to my Chevy is that the waterpump connects to the waterneck and the radiator does too. The waterpump connection to the waterneck looks like it would make it so water would be flowing through there all the time? And the thermostat just blocks the upper radiator hose connection until it's hot enough to open?
I.E. my Chevy just has upper radiator hose connected to waterneck and waterpump connected to lower hose and 1 heater hose. Other heater hose goes to intake manifold. It's serpentine too which means the waterpumps spins the opposite way I believe?
I guess that's all beside the point anyhow, I just don't understand water flow in these motors all that well.

You can kinda see the waterpump to waterneck connection in the photo below:
http://i121.photobucket.com/albums/o219/ernestmayhand/Ivan%20Cutlass/_DSC0268.jpg

Your '71 350 has a serpentine belt? That is not original. The stock 350 wp must rotate in the same direction as the crankshaft. If its going in reverse, you may have found the source of the problem. As far as I know, there are no reverse-flow Olds waterpumps (but I could be wrong here).

As for that hose that comes out of the top of the wp and goes to the waterneck.... that is the bypass hose. As I recall, when the T-stat opens, flow through the bypass drops to near nil due to the waterflow through the main passages into the engine.

Your '71 350 has a serpentine belt? That is not original. The stock 350 wp must rotate in the same direction as the crankshaft. If its going in reverse, you may have found the source of the problem. As far as I know, there are no reverse-flow Olds waterpumps (but I could be wrong here).

As for that hose that comes out of the top of the wp and goes to the waterneck.... that is the bypass hose. As I recall, when the T-stat opens, flow through the bypass drops to near nil due to the waterflow through the main passages into the engine.

No not a serpentine Oldsmobile, just comparing this to my Chevy, sorry to confuse.

Popped in my old radiator that came out of my Chevy, plugged a couple inlets/outlets in it and the car's staying right at thermostat temp. Must've been something plugged up in the old radiator I guess. The motor it had been attached to overheated which is why we put this 350 in there, so that would probably explain why it overheated.

Thank you for letting us know.:)