off topic help

I have a yukon with lifter noise and one cylinder fouling a plug. dealership put new lifters in at a great expense and still had lifter noise.Pulled apart and found the new lifters were defective. another new set and now the noise is back.What could be wrong guys. They say the oil pump is within pressure specs.but think oil is going by one cylinder ring. I never add oil and it never goes low on the dipstick.I am so baffled.What can you fuys tell me here. can I get hotter plugs or some kind of oil that makes the lifters quiet.help. there has to be some sort of solution.it does have 190000 miles on it but dealership swears that should not be an issue..

I would get a live gauge and check what kind of oil pressure your actually getting in the upper galley of the motor. I have seen bad cam bearings (assuming non overhead cam) leak off the oil pressure/flow and then the lifters would clatter.

The one cylinder fouling plugs would indicate to me bad piston rings. The oil ring broken maybe. Valve guides would have to be really bad to cause a fouled plug.

Need to know the age and model of the motor to really help you much more. Just guessing at the moment.

WHY would you not at last throw us crumb here and post the year?

If it is pre DOD, for sure lifter noise and a fouled sparkplug likely have little in common.

What year, what engine and what cylinder is oil fouled?

2007 5.3 engine thank you

I'm not sure about the 2007 model year, but the 5.3 engine is known to develop piston slap. The noise is annoying but mostly harmless.

I'm curious how you determined the replacement lifters to be defective.

Camshaft lobe? Ben

The VLOM that controls the unlocking of the litters on the displacement cylinders is bad. It is the valley plate under the intake. It should have been replaced the first go around. It is likely gummed up and not allowing the lifters to completely lock and unlock, collapsing them.

Go to google and type in gm piston slap class action lawsuit. In 2000 I bought a Chev. 2500 with the 6.0L engine. Engine rattled when it was cold, warmed up-same thing. Traded it in on a 2001 2500 hd, same thing. I had gotten an extended warrenty to 60,000 miles. Had someone tell me about the lawsuit and they were replacing some engines. I went in and ask the salesman I bought them from about it and he said he didn't know anything about it, supposedly called someone and told me they said the same thing. I came home, got on the computer, typed in gm piston slap lawsuit and all kinds of things came up. I printed off several pages, went back a few days later and ask if he had heard anything about it, he said no, laid the papers on his desk, he got on the phone, hung up and said they would be calling me in a couple days to bring my truck in and have it looked at. Guy called me a couple days later, was kind of nasty attitude, told me, "If that thing isn't noisy, you won't be getting a new engine". I dropped it off the night before, the next day before I left for work they called me back and told me they had ordered a new engine. A friend of mine worked there part-time and never told me they were replacing engines. I figured they were told not to say anything to anyone that they were replacing them. I had about 59,000 + miles on it and now have just under 177,000 and the engine has about 118,000 and is still quiet. My friend told me after I had it replaced that they had replaced several engines. I figured for as much as you pay for vehicles anymore you shouldn't have to put up with the noise. Both of the truck were noisy from the start.

Sounds like that valley plate under the intake sludged up.