Replaced all 24 VLA yet tapping noise continues at idle until 2,900 RPM and stays gone as long as above 2,900 RPMs.

Montero Limited 3.8L motor has 173,000 miles and has always run good and doesn't burn oil at all or leak much either.

Yes, I inspected the new VLAs and they seemed good, and I performed the 0-3,000 RPM flush-bleed upon replacement... 50+ times. Noise got a little better here and there for those 50 bleed cycles but never went away.

When the original VLAs started making noise about 500 miles ago the bleed cycle process would stop it for 2-3 days. And I'd only have to do about 13 cycles to make them quiet for those 2-3 days. That worked twice, maybe three times, and then it wouldn't go away so I figured a VLA was completely bad.

It sounds as though the same Valve Lash Adjusters are making the exact same noise as the replaced ones...Passenger side #3 Cylinder. Out of the 24 VLA only two were noticeably bad when I removed them...both from Cylinder #3 (the 2nd from firewall on Passenger side). One was exhaust and other was an intake. But the Exhaust VLA was very smashed up and Intake was only slightly.

When I did the VLA replacement I also changed plugs and noticed all the cylinder heads were very dirty with carbon. Took a flashlight and looked down spark hole. That's the only thing out of the ordinary I noticed. I also cleaned the rocker shafts and all the small oil ports...all seemed clean and clear.

Do you think #3 Cyl is so dirty that the valves are not seating and causing the Exhaust and Intake VLA to get banged up?

I thought about timing but it was redone 12,000 miles ago and if it was a slipped belt it would likely beat up all or at least several valves right?

Plus the noise totally stops at 2,900 to 3,100 RPM and then returns when RPMs drop below 2,900. I've tested it several times up to 5,000 RPM and it's quiet after 2,900 RPM while driving load or parked.

Any suggestions? I want to kick its windshield out and cut it in half right now!...20hrs and $300 of my time/$ maybe wasted.

My plan is to rinse my oil/crankcase system with 10w transmission fluid for 2 hours at idle and some RPMs also for short periods. Then add motor flush at double strength, if the 10w tranny fluid detergents don't work. And follow the instructions with the flush product. Finally change oil and filter and do a coolant back flush and refill also (because it's due).

If that doesn't stop noise then I'll add double strength fuel system cleaner to 10 gallons fuel and run that at mixed idle and high RPMs. Maybe that will clean carbon off valves and seats.

And lastly regardless if these work I'll add something like Blue Devil or Green Seal head gasket sealer to my fresh crankcase and fresh coolant to reinforce any weak areas I scrubbed too much with cleaners.

Any other ideas for me to try?

 

I wonder if your oil pump is not putting out sufficient flow/pressure. I'd have that tested. It is also possible that you have plugged or restricted oil passages in the upper part of the engine.
I'm sure you've done your research, but if it were up to me, I'd keep transmission fluid in the transmission and engine oil in the engine oil pan... They are VERY different kinds of fluids (ever wondered why one is called "oil" and the other "fluid"???) and you might be asking for more trouble than its worth by doing the "cleaning" like the one you are proposing. It sounds to me like the stuff Jiffy Lube does on fairly regular basis accidentally (put wrong fluid in the wrong hole) and it hardly ever ends well. If you really insist on cleaning the engine internally, there are additives you can buy to add to the engine oil. That stuff is compatible with engine oil, provides proper lubrication properties and you run the engine with it for few thousand miles, drain and refill with clean oil. Having oil and additives circulating in the engine at working temperature for long time is much more likely to provide proper cleaning of all the small passages (slow and gradual cleaning). I would recommend you go with that route.

 

I'm starting to think I have poor oil pressure, or a clogged passage somewhere too. The noisy completely stops at 2,900 RPM and above.

I am going to do a series of motor flushes before ripping that PITA apart again though.

Starting with Seafoam into crankcase for couple hundred miles. Then followed with a transmission oil rinse for 30 minutes idle and motor oil refill. Then 15 minute motor flush if still present. Followed by oil pan cleaning/inspection.

If the flushes don't work I'm going to try replacing the rear cam o-rings / gaskets. Ford's have similar issues with their cam o-rings. Another forum poster here said when they changed the o-rings on their 90s Montero their VLA noise went away immediately...didn't even change the VLAs. They think the bad cam seals allow either air induction or loss of enough oil pressure to make the VLA not properly work. Possibly the case. Maybe I should try this first, lol.

 

I also want to clean the intake and pistons. I'd like to use a vacuum tube on the intake plenum to suck in Seafoam or other cleaner from a bottle.

Do you know what vacuum tube I can use for that?

 

The brake booster or PVC is a direct shot to the intake upstream of the throttle body.

I can't see how leaking seals on the cam thrust plates could be a culprit. I think you have reduced oil flow and or pressure to the upper head and rockers due carbon, crud buildup, or bad pump.

I would do the sea foam but stear clear of the ATF flush. You have brand new seals in the VLA's which don't need to be softened by the ATF.

 

There is port on the oil pump and with proper tools (or at a shop) they can test the oil pressure from the pump. You should do that first. I doubt that changing cam o-ring will increase oil pressure. The top of the engine is not pressurized.

 

I posted another topic to explain what happened. The NEW timing belt kit I used failed and the tensioner didn't last more then 12,000 miles. Causing the belt slap that EXACTLY mimics the VLA failure and noise symptoms.

What a pain. Don't buy the crap from CNS Auto Parts, eBay vendor. The kit was $105...came with belt, tensioner, idler, water pump, and associated gaskets for pump and valve covers.

What brand should I use to replace?