Abstract: The steam can be generated using any heat source such as solar energy, wood, crude oil, biofuel, etc. In contrast to the Internal Combustion (IC) engine which must use a specific type of fuel to run. This flexibility of energy sources for the steam engine encouraged as to build a model of it. Moreover, the renewable energy resources represent the most important modern research projects in alternative energy resources field due to the limited fossil fuel resources. The aim of this research is modify an IC engine by manipulating the valve’sopening and closing timing. In another words, the camshaft in IC engine is modified to make it run as external combustion engine as showed in details through the manuscript. The amount of steam needs to run a 3.5 HP engine (our case of study model) is about 3 g/sec at 4 bar steam pressure and this flow rate will decrease when steam pressure increases. The modified steam engine model tested at 4 bar steam pressure and showed promising results. The theoretical efficiency expected to be up to 34% at the tested pressure.