I have a 1990 Plymouth Voyager with 130,000 miles on it (Mitsubishi
2.5L 4 cylinder engine). Recently a leaky radiator led to a cracked head, so I put on a new head and radiator. It worked great for several days.On a couple of cold mornings my wife revved the crap out of the engine to try to warm it up quickly (while I cringed inside, trying to decide which is more important, marital bliss or a car that works!), and now whenever it's cold, I hear a clacking sound from under one end of the valve cover. It smooths out when the engine warms up.
My pet theory so far is that the overrevving with cold 10W30 oil in below freezing weather damaged the oil pump. But that's just a guess. It also seems possible that there is an obstruction in some of the oil holes between the block and the head, or that something is actually wrong with the new head.
So let's hear it, gurus. Does my oil pump theory hold water? Would it be worth trying a switch to 5W30 oil to see if a merely weakened oil pump might hang in there a little longer? There are no valve clearance adjustments on this engine, but should I pull the valve cover and have a look for shiny spots? If it *is* the oil pump, is that a difficult job (considering that I just did the head)?
Thanks in advance... David