1UZFE V8 clacking redux

[Amskeptic]

I have read on many Lexus sites the complaint of clicking ticking engines.
I watched a posted You-Tube video of an IS300 clacking away in exactly the same manner as my '92 LS400 with 105,000 miles. Many have mentioned that it seemed to be the #7 intakes (back left).

My LS400 had this very tack tack tack tack sound the day I bought it with 95,748 miles on it on June 3, 2009. I told the salesman, "nooooo problemo, I'll just adjust the valves." I adjusted the valves . . . what a job.

From front to back right exhaust/right intake/left intake/left exhaust
bird's eye view, these are my current valve clearances:
.014 .014/ .014 .014/ .012 .012/ .014 .012
.008 .009/ .009 .009/ .009 .009/ .010 .010
**********************************
.007 .006/ .006 .008/ .006 .006/ .006 .006
.010 .009/ .011 .011/ .011 .011/.011 .010

Well, dang if the engine didn't keep clattering away right up there at #7 intake area. I checked the clearances throughout the engine again, stone cold, no change in numbers.

I killed each cylinder via the spark then the fuel injector plug (too much blame on direct injection injector noise from dealers in other posts), and absolutely no change in this clack clack clack.

I did a Seafoam 20 minute soak blow smoke + 1 quart of water to decarbonize combustion chambers then a 5,000 rpm quarter mile with a couple of blasts to compress carbon deposits (if there was carbon/piston interference, I could expect a reduction in noise back at idle), but no dice, this noise is as steady as ever.

I did an Idle The Engine With No Oil to see if oil starvation in the cam area was the cause (if the right side of the engine got clacky with oil light on, then I could assume that chronic oil starvation was the culprit over on the left side), no change. 10-30 wt Valvoline is curently in the engine up to but not exceeding the full line.

I noted that my left side clearances were close to minimum while I kept the right side loose, but the right side is still whisper-quiet, left side is nasty old Buick collapsed hydraulic lifter sounding.

Valve spring tension is excellent and consistent according to the Schley tool.

Under the car, the sound is alarming. I almost figured we had a loose torque converter bolt tapping the bell housing, but all are tight, and the stethoscope found only the barest immediate tapping noise up at #7 valve cover back bolt.

This noise comes and goes. It can sit and idle quietly for 40 seconds then bang, its back. A fast idle (1,800 rpm to build it up oil pressure/volume) in the cam area) does not quiet it down. But I think now that it might relate to the tappets rotating in the guide bores.

I throw myself at the mercy of the forum here.
Anybody else suffering this clackclackclack insult to dignity?
Anybody ever gone into the heads to find it?
Valve guides? Seats? Tappets with ovalized/excessive clearance to their bores? Do the hardened inserts ever recede inside the tappets where they cock so that at certain points in their rotation they might open up a clearance or sumpin'? I am so guessing.

I love the sophistication and intelligent engineering of these cars, but I desperately want it to sound civilized.
Colin

 

[Amskeptic]

I have read on many Lexus sites the complaint of clicking ticking engines.

I throw myself at the mercy of the forum here.
Anybody else suffering this clackclackclack insult to dignity?
Anybody ever gone into the heads to find it?
Valve guides? Seats? Tappets with ovalized/excessive clearance to their bores? Do the hardened inserts ever recede inside the tappets where they cock so that at certain points in their rotation they might open up a clearance or sumpin'?

UPDATE:

I threw myself to the wolves instead, and disassembled the engine down to the camshafts (a good time to replace the timing belt so I did).


After recording all valve adjustments, I removed the camshafts and lifter "buckets" or "tappets" or whatever and laid them out all along the sides of the car:


Found the problem was poor lubrication at the #7 rear intake valve which had indeed drilled a depression into the lifter's hardened pad. Fortunately the valve stem still looked OK, but I will keep an eye on it if any surface hardening of the stem has been damaged:


Apparently the 1UZFE engine exhausts the crankcase air from the left head area, so delicately lubricated spots can get compromised by carbon-laden sticky goo if people like the prior owner don't change the oil in a timely fashion. Maintenance is Good. Better still is the silence with this engine now glides about its business.
Colin