If the engine is loud and squeaky during cold start, check the use of engine oil. If inferior gasoline is used, it will also lead to the decrease of engine power, the increase of carbon deposition inside the engine and the increase of engine noise.
If the engine vibrates, it will also cause engine noise. The creaking sound should be the abnormal sound caused by the slippage of the water pump belt or engine belt after aging, or the wear of the water pump impeller, water pump bearing or generator bearing after lack of lubrication. It may also be caused by the friction between the engine claw and the bracket when the engine jitter is large. Check these one by one, and you can find the reason.