VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Radiator over flow on 28 ?

We'll I finally got my 28 Chevy coupe running for 5 to ten minutes at a time! It runs pretty smooth with no major adjustments so far!!The radiator does drip fluid from the overflow pipe when running and when when the engine is stopped quite a bit of water flows out of the radiaror over flow tube? As there is no preasure sensitive radiator cap how does this system work? I just have a standard cap, with no moto meter.What might cause the water to flow from the overflow tube. I wouldn't think this is normal but could it be?? With the cap tight should the engine be able to run with out losing any fluid? Where does the preasure go?

Scott
sdakss@aol.com

Hi Scott,

Your 28 cooling system is not a pressure system. If you remove the cap and take a look down the neck of the radiator you will see that the overflow pipe enters below the seal on your cap. Therefore, if the water expands it will be forced out the overflow and not make like Old Faithful on your 22 coats of hand polished lacquer that you have on your hood.

It takes 4-cylinder owners a while to learn to fill the radiator, let it achieve it's level and then leave it alone. When the engine is cold you may look down the neck and not even see the water. That may be the level that it is most comfortable operating with.

It is really not satisfactory to try to make the system a pressure system. The weak link is the waterpump packing. It was not designed to withstand any pressure.

Thanks! Ok then if I can't nessesarily see the water in the radiator how do I know if there's enough in the radiator? I guess this is the reason for a moto-meter? Also, someone told me to put marine grease in the water pump fitting. Is that a good idea?

Scott

Experience will tell you when you need to add. If the water gets hot the motometer will let you know if the geyser don't tell you first.

Neither the Repair Manual or Owner's Manual recommends any lubrication in the grease cups except a "grease of high quality with a high melting point". However, a good marine grease would work well in this location only.

If you get water loss after shutting the engine off it is likely due to air buildup in the head. The air likely leaks past the water pump packing while running. The air bubbles will likely be small while the engine is running and may or may not be able to be seen at the top of the radiator when the engine is running. The air bubbles will expand greatly when the engine is shut off. The result is water being forced out of the radiator. It is not necessary for there to be a water leak at the pump to draw air past the packing. I have had the problem with my '28 on tours last year. Once I got the packing tight enough the problem went away. You should have water visible when looking down the radiator neck but only just above the core.

The same water loss can occur if there are hot spots in the head. These are most often due to buildup of deposits, bad castings or poor flow. Cleaning the block and radiator should eliminate them.

A water proof lubricant is required for water pumps. It also needs to be high enough viscosity at 200 deg F to help seal the packing. Some marine lubricants are good others too low viscosity.