engine, pecking noise, sounded like lifters

[Poling]

Have a 90 Q45, 110k on the engine. It sounded like the valve lifters were sticking and were pecking. I had the lifters replaced on the right side, also had the timing chain changed at the same time, but it didn't fix the problem. The closest Infiniti shop is about 3 hours away. The mechanics that did the work were not Infiniti mechanics, but they are excellent mechanics. They just don't know the engine well enough to diagnose the problem.

Poling

[elwesso]

Could it be the chains rattling??? Did you have your chain GUIDES replaced, that needs to be done ASAP!

How sludged was the engine when you took it apart?>

[Poling]

The guides were replaced. They were completely worn out. There was some some sludge, but very little.

[elwesso]

Maybe try running a can of seafoam through it before an oil change... cant hurt

[911/Q45]

Were all the guide pieces recovered? If not, the oil pickup could be clogged and oil pressure could be low.

[elwesso]

Thats another possibility.

Do you by any chance get an oil light....

[DAEDALUS]

Check the oil pressure regardless. What kind of oil are you running? You're sure it's not the injectors clicking?

[elwesso]

I didnt think of that, the injectors make sort of a sound like feint valve tapping.....

[Poling]

I'll have one of the mechanics check the oil pressure again. This is not a feint tapping. I sounds like metal striking metal, type of sound. I also know sounds can be really tough to analyze in a motor. I will have him check the injecters, but I can't imagine them making this much noise. It is a really heavy tapping. I would suspect something like a rod bearing, but it is in the top of the motor.

[Q451990]

Sounds like a bad HLA (hydraulic lash adjustor AKA Lifter) to me. Does the sound come and go, or is it always there? Even new lifters, if not handled properly, can get air in them and cause this type of noise.

Heath

[Poling]

It is fairly constant. At certain low rpm's, not idle but about 900 to 1000, it will sometimes stop. I haven't driven the car much for almost a year. This has been an ongoing problem. Is there any way to check the lifters (if the valve cover is pulled), to make sure they are working?

[Poling]

Have had the oil pressure checked. It's good.

[elwesso]

What was your pressure...??

[Q45tech]

Need a cold vs rpm, warm up vs rpm and extreme hot idle pressure and rpm increment............to evaluate oil pressure vs bearing clearnances always donne with brand new oil and filter and a quality brand in 10w30 where the viscosity vs temp charts are available.

Good oil pressure good enough for what?

If it is HLA, then BG Quick Clean for Engines process is about the only thing that will eventuallly dissolve the blockin varnish.......mutiple treatments multiple short oil changes.10-15 years of oil abuse cannot be corrected over night.