QuestionWe purchased this van a year ago with low mileage (100,000) Shortly after purchase, the engine began make a very loud ticking sound when idling. We have been told many reasons from "sticking valves", "sticking tapets", "usual with this model and year" and the scariest of all "oh no, you will have to replace your motor soon" Who is correct?
AnswerHi Dennise,
That is usually the sound of an excess of space between the tappet/rocker arm and the valve stem which can be due to a sticking valve or a hydrualic tappet/valve lifter not pressurizing fully. I am not that expert on describing or hearing engine noises, but if it sounds like a clicking from the top of the engine (valve cover area) that could be the hydraulic valve adjusters not having sufficient oil pressure due to the oil being too low a weight, or being diluted with leaked fuel or coolant getting into it, or an oil pump that is not putting out sufficient pressure at idle speeds. You could smell for gas on the dipstick, look for foam on the dipstick which is a sign of coolant leak, and/or feel the oil viscosity with your finger tips, or put a gauge in place of the oil sensor unit and measure the idle oil pressure. It usually should be around 5 psi minimum at idle, but tell me which engine you have if/when you write back. See if you can find out what weight of oil is in the crankcase from the previous owner, then change it and use the next higher weight range in a drain and refill. That will raise the oil pressure at idle.
If the engine sat unused for a period of time before you bought it, there may be some crud that is partially blocking one of the oil supply lines to the valve train. If that were part of the history it might be worthwhile, just before you change the oil, to add a can of additive to the oil which helps to dissolve such internal build-up. Follow the directions on the product, then drain and refill with the next higher weight of oil.
That is a modest-cost approach to solving the noise issue. I doubt it is an issue requiring your to "replace your motor soon". If the noise doesn't disappear after the oil change then checking the oil pressure with a gauge is the next step, and evaluating whether the oil pump only may need to be replaced.
If the noises sound more like from the engine block that indicates the same sort of problem with oil pressure, so try to correct that situation by viscosity increase, and if that fails do the pressure measurement and then go on from there.
It may be a clogged oil line, or wear and tear on the engine, but hopefully increased viscosity will do the trick.
Roland
