Strange Cooling Issue on 5.7 engine!

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I have a 1991 Chevy Suburban V1500 with a 5.7 TBI with automatic trans and 130K miles. I am very slowly going over it and upgrading and fixing as I go. I have already done a complete tuneup...plugs, wires, fuel filter, distributor, exhaust. In addition I have replaced the radiator with an aluminum one, installed a new water pumping 195??? degree thermostat also. Whatever the factory called for but I think it was a 195. It runs fine, temp runs about 185 when cruising but seems to warm up to 195-205 when I hit a hill going slow or crawl in town and even sometimes when I am idling. It has never overheated while I have had it.

SO.....if I start it cold and run for a few minutes and stop (not long enough to get to full operating temp) and shut down the engine....I find the upper radiator hose hard and full of air.....the radiator cap and passenger side of the radiator are hot but upper hose and drivers side of the radiator are cold to barely warm....if I leave it sitting (not running) for a few minutes the drivers side warms up. I smell antifreeze occasionally and the reservoir slowly (over months) lowers but I cannot find any leaks after repeated searches.

I’m thinking that the passenger side heating first is normal because of the heater core getting water from the engine and putting it back in the radiator on that side before the thermostat opens. The air in the hose bothers me but I have been unable to get it to go away. I don’t seen any bubbles from a head gasket leak. Although I am not sure I know what to look for and when on that. There is no oil in the water or water in the oil, that I am sure of.

When the engine is hot the top hose is hard and full of water.

I feel there is something wrong but what?

Where do I start looking? Purge air more, water pump, thermostat, coolant pressure test???

Any ideas?

Inquiring Minds Want to Know!