My car is running extremely rough it blew blue smoke then white smoke also made a whining/grinding sound. The mechanic has given me several answers to what he thinks it is but nothing is adding up. One call he said a valve had dropped. Then another call was the oil gallery has failed and I need a new engine. He says he has tested the compression and they are all reading normal, so not a problem with the valve then, right? Would the oil gallery "failing" cause me to have to replace my whole engine?
My car has 100000 miles.
My car has an automatic transmission.
Testing and diagnosing will give a technician a good idea of what to expect will be found with internal engine problems, but you can never be totally sure until some disassembly and inspection has been done. Test results leading to an expectation of finding a blown head gasket can turn out to be a cracked head, or a failed piston.
Opening up an engine that has 100,000 miles on it is risky. You really need to do some hard evaluating on what the vehicle is worth and what it may actually end up costing to fix it right. Too many engines get disassembled and partially repaired, then put back together with many old parts that should have been replaced or reconditioned at a machine shop. Of course it usually due to trying to control costs, but it frequently results in a repaired engine that burns oil, is noisy, or performs poorly. These partially-rebuilt engines rarely last long enough to justify what was invested in the repair. Have it done right or don’t do it at all.
If you decide to get this fixed, consider enlisting a qualified mechanic who can perform the necessary checks to diagnose your rough running condition and the smoke you’re experiencing. Once this is done you’ll have a good idea of what will need to be fixed and from there you can proceed with the repairs that are necessary. Good Luck.