Thank you for specifying the V8 engine. Many people forget that. Are you sure it's the lifters? It would be a good idea to have the oil pressure checked with a mechanical gauge if you haven't already. The warning light on the dash will stay off as long as the pressure is above approximately 7 psi. That's not very much, but even that should keep the lifters happy. Normal pressure at idle should be around 30 - 40 psi. If it is low, especially more so when the engine is warmed up, suspect worn crankshaft and connecting rod bearings. They can be replaced without removing the engine. Low pressure when the engine is cold could be caused by excessive clearance in the oil pump or debris holding the pressure relief valve open. If the relief valve is stuck partially open, you will likely have normal pressure at higher engine speeds because at those speeds, the relief valve is normally open anyway.
If the pressure goes down as engine speed goes up, suspect debris clogging the pickup assembly screen. That requires removing the oil pan to clear out the junk.
If all 16 lifters are making noise, I would suspect a rather severe problem preventing oil from getting to the passages the lifters live in. There's a passage on each side of the engine. If all the noise is coming from just one side, I'd expect to find blockage in that passage. If the noise is coming from both sides, I'd more likely expect to find low pressure.
It's more likely the lifter itself is defective and should be replaced. Normally I don't put much faith in "mechanic in a can" products, but this is one time you might want to try an oil additive. Lifters develop a wear pattern where they ride on the camshaft lobes so it's important to not mix them up, and it's possible for a new lifter to wear down very quickly if it's installed on a used, worn camshaft lobe. You will be better off in the long run if you can get the old lifters quieted down.
One trick I saw done twice by one fellow I worked with was to add a quart of transmission fluid to the oil a day or two before the next oil change. He bought two neglected cars that had severe sludge problems. Adding transmission fluid dissolved the sludge into the oil so it could be drained out. I never tried this myself. The guys at your local auto parts store will be able to recommend a product when you tell them the symptoms. "Sea Foam" is one product I've heard mentioned many times, but I've never looked into it and I don't know if this is its intended purpose.
I've had a bunch of cars with 318 and 340 engines but they were older than yours. They all specified 10W40 oil. My newer stuff wants 10W30 but due to the high mileage, I still use 10W40 with good results. 109,000 miles isn't "high mileage" in my book, but you might try the thicker oil if you aren't already. Oils are much better today than 25 years ago so in your engine, the thicker oil should lubricate just fine.
If nothing else works, keep in mind there are other things that can sound like noisy lifters. It might be necessary to remove a valve cover and feel the rocker arms while the engine is running, and look for wear on the ends of the pushrods.
Caradiodoc
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Saturday, February 13th, 2010 AT 10:23 PM
