Buick Park Avenue engine smoking

We have a 2000 Buick Park Avenue that was losing a lot of coolant. My husband has replaced the radiator, thermostat, lower intake manifold and the lower and upper manifold gaskets. After all this, there is white smoke and an oil burning smell coming from around the oil reservoir. He is prepared to change the head gaskets next. Is there anything else this could be or that should be checked?

The engine began smoking after the radiator and thermostat repair, which prompted the intake manifold gasket repair. There have not been any codes or overheating, according to the dash read-out.

Any suggestions would be appreciated.

Did the engine overheat when it lost coolant? If so the heads and/or lower intake may be warped or cracked. A pressure test may be very revealing.

Was the oil changed after replacing the gaskets? If not the residual coolant may be boiling out of the engine oil as it heats up. Coolant is also very bad for the soft metal in engine bearing shells.

Thanks for your response.
The car never seemed to overheat but our son had it at college so we aren't sure what all went on. He said it never showed that the temperature was above normal in the dash read out. It seemed to go through a lot of coolant. We went to visit and brought him a new radiator cap, hoping it was a simple issue. All the coolant we added then drained out after he drove it just a very short distance. It very well could have overheated at some point.

Anyway, my husband is in the process of changing the head gaskets. He is also putting a new water pump on while he has the engine apart. Hopefully, this will solve the issue.

It has been a great car and we would love to have it running again!

I'd look at the water pump and the coolant elbows.

There are plastic and metal replacement elbows. I found out after I had used the plastic one. Don't know why they weren't always metal.

Consensus seems to be, to replace O-rings provided, with better ones. Dorman 47065HD.

Mine didn't smoke, just had coolant smell and loss. Good Luck

Did you check for plastic degradation in the upper plenum where the egr tube passes through it? The tube can contact the plenum and heat it so it melts, creating a hole.......usually when this happens, when you take the upper plenum off the lower intake, the cavities of the lower intake are full of coolant...