You need to have the oil pressure checked manually with a gauge first to verify they are bad. One lifter maybe, but all failing at the same time, no.
November, 8, 2011 AT 3:50 PM
Sorry it is a 3.0L V6. I thought that if one lifter is bad that you may as well just change them all.
November, 8, 2011 AT 5:27 PM
That is true but if they all are making noise, it may be an oil supply issue
November, 8, 2011 AT 6:12 PM
ASEMaster6371 is right. Not all of them are going to fail at the same time. Plus, the 3.0L doesn't use lifters. They have tiny oil-filled lash adjusters in the tips of the rocker arms. On very high mileage engines they can wear a spot on the bottom that exposes a very small hole for oil to drain out of. That can make them noisy, but it will affect just that one. I have one on my '88 Grand Caravan that is noisy enough to get people out of my way in parking lots. That engine has over 380,000 miles and it's been making that noise for over eight years.
A more likely cause for your noise, if it really is affecting all the lash adjusters, is the oil filter. Many of them do not use a check valve to prevent oil from draining out of the oil pump when the engine is off. When the engine is started, the pump has to push the air through the system before it can draw a prime and start pushing oil.
My first experience with that was many years ago at the dealership with an upset owner of a Dodge Shadow. The engine rattled severely for about three seconds after startup, then was perfectly quiet. Of course that started right after I worked on the car, ... For a maintenance alignment. I never even opened the hood, but she assumed the noise was my fault. After an hour of yelling and accusations, we found out her husband had changed oil and filter the day before. He used the same Fram filter as always, but they may have made a design change that eliminated the check valve. Some engines have the check valve built in so they don't need one in the filter.
The fact that the noise goes away when the engine warms up suggests the oil pressure, oil pump, and engine bearings are okay. Problems with those things will make the noise worse when the engine is warm. If you DO have the oil pressure tested with a mechanical gauge, be aware the 3.0L runs extremely low pressure at idle. That is perfectly normal, and the sending unit is calibrated to take that into account on the dash gauge. Six pounds of pressure at idle is WAY too low for most engines but is normal and acceptable for this engine.