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After getting the 1929 633 started after sitting for between 15-40 years I ran into another issue that has me scratching my head.

As an update, after rebuilding the carb, new battery, rebuilding the starter motor, changing all fluids, new gas, new fuel filter, adjusting the points, changing the plugs and putting in new wires, the car started like a charm. An exciting day, even with all the smoke triggering the CO and smoke detector causing the alarm monitoring company narrowly avoiding having the fire dept come for a visit 🤣

Now that the engine is running smoothly the issue is with the coolant. I previously drained and refilled the radiator with new antifreeze a few months ago. After the engine ran for a few minutes (10 or so) I obviously had air in system somewhere causing the coolant to overflow. Turning the car off and on again topping up the rad each time the water pump eventually purged the air out of the system and the bubbling stopped.

After topping the radiator up one final time the rad is still over flowing. This time I do not see bubbling in the rad but the volume slowly rises until it overflows. When the engine is off the level decreases down to the point that I do not see any antifreeze in the top of the rad. When I start the car again fluid level rises back up again until it overflows. Turn the car off and it slowly goes down again. It takes about 2-3 min for it to come up when the car is running and 2-3 min for it to go down again when turned off. It’s like watching the tide come in and out, slowly but non stop.

Options are: 1) head gasket? - but no bubbling is seen, but I haven’t checked the oil yet. 2) water pump issue? - I am not sure what this would look like when peering into the radiator. 3) thermostat sticking?

All the above? None of the above?

Otherwise the engines purrrrs nicely.

Thoughts? Suggestions??

Sage advice is always welcome. Thanks.

Cheers

Mel.


Sent from my iPhone

The coolant is expanding when it gets hot and contracting when it cools. It's normal, they all do that. The cold water level is well below the filler. If you top it up it will overflow when it gets hot.

Thanks. That is interesting. I expected expansion, but when it’s cool I can clearly see the top of the core (don’t see any coolant at all), I wasn’t expecting to have that much of a difference in the amount of expansion when warmed.

That is not normal, the water level should not drop below the top of the core.

Your water pump may be leaking at the seal. It is possible for a water pump to leak air in at the seal when the engine is running. This will tend to form air and steam pockets in the water jacket and displace coolant out the overflow. The water pump can have this condition and yet not leak when the engine is stopped, or it may drip coolant.

The solution is to tighten the packing just slightly, assuming the seal is in good condition and properly lubricated. A water pump with worn bushings won't allow the seal to work as it should, and it can be expected to leak air in and coolant out.

An excessively tight fan belt can also cause problems.
A new pump or newly rebuilt pump ought to be run for an hour or so with the belt a little loose to allow bearings and the seal to seat. The seal may require one or two adjustments at first. Usually, 1/4 to 1/2 turn of the packing nut will be enough. Too tight will cause the seal to fail.

A pinhole leak in the lower radiator hose or in the core itself can have allow air to be pulled into the system, though the pump is the more likely culprit.

A leaking head gasket can also cause excess coolant displacement. Was the head re-torquing procedure followed?

Some coolant expansion is normal, but it should not cause the core to be exposed after running and stopping the engine. A radiator filled to the brim when cold should not expel much more than a pint or two of coolant at operating temperature.

Thanks. Those suggestions make sense. I will look more closely what the water pump.

Thanks everyone for the suggestions. I hadn’t noticed, but the water pump itself was seized after sitting for so long. Lots of TLC, plenty of oil, and grinding off the rust build up and it now works like a charm. Coolant level is proper, engine is staying cool, and all is sweet again.

Thanks for all the tips, they inspired me.👍