Subject:	jet valves
Question:	I have worked on cars a long time ago. Prior to 1960. I now have a 2.4 mitsubishi engine in a 1992 dodge ram 50 pickup with automatic transmission. The repair manual shows how to service the jet valves in the cylinder head. I just don't know what their function is. Any info will be appreciated. Thank you. The reason I ask is I am going to install new valve seals because of oil consumption and would like to know more the purpose of the jet valves.
Answer:	Roberto, I do know much about the jet valves, but from the little I do know, they are used for allowing extra air to mix in the combustion chamber. They are a good idea, in theory, but many people with heads that have jet valves experience cracking in their heads. It's not the jets themselves that cause the cracking, but the steel jackets that go around the jets. Because the jackets are steel, and the head is (I believe) aluminum, the two metals dissipate heat at different rates; thus causing cracking. Many folks get new heads that do not have jet valves. But that's usually on turbocharged engines. I don't think your engine gets hot enough to cause a problem. I would just service the jet valves per your manuals instructions. Good luck!