Mechanics

HYDRAULIC LIFTER PROBLEM / NEED DIAGNOSTIC HELP

1930 Nissan 300ZX

I have a 300zx 1990 (z32) non-turbo, I have a re-occuring tapping problem. I have tried cleaning the oil out with sludge remover, putting in recommended oil and lifter free solution. I have tried getting advice from several mechanics but they all diagnos the car as having a broken lifter without even taking a look at it. Im confused as if the lifter had mechanical damage the tapping should happen all the time, however it only happens ever now and again, does anyone know of other possible causes of this tapping sound? Im not sure if it is plausable but I have a feeling that timing is off, as usually when the tapping noise occurs the engine doesnt run well, idle drops, slow pick up on accelerator etc.

Also does anyone know a place where I can get a good deal on a set of hydraulic lifters for my 300zx?
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Temjin
August 8, 2006.



I just read somthing about if air gets into the lifters it can cause them to make noise, this would help explain why this problem only happens on and off, as air could be getting trapped and then released.

Hmmm, why dont mechanics ever tell you this stuff? They just want to rush in with the big overhaul of ever possible part that may be responsible (well most of the mechanics in my experience anyway).

Tiny
Temjin
Aug 8, 2006.