Margate330

I'm not strong in this area so I hope others can help.

Don't quote me but I think your other cylinder compression readings look ok and good.

Someone please correct me if that's wrong.

Mesquite77

>>> How bad can it be to work on this

Compression on others is fine, good even.

That engine is coming out, working on bank 1 is a pain, and don't even bother trying to remove bank 1 valve cover with it in there, (if scoping reveals a score, its replacement engine time, so is still coming out). Drop the subframe, then its almost satisfying working on it outside of the car, inside there is little you can do to fix it, if the head needs to come off, then timing cover comes off, and its needs to be out to do that.

https://www.clublexus.com/forums/rx-...ve-spring.html

Margate330

At 85 psi compression, it looks like it's running at about half compression.

It's not a dead cylinder but compression is low.
What can cause that on our cars?

I tried a quick YouTube search but didn't find much.

Leeper

Did the compression stay at 85 or did it drop slowly? Usually it will drop pressure slowly that is 1 of 3 things going one
#1 - valve(s)s - could be a slightly damaged valve or as simple as some carbon debris not alowing it to close completely
#2 - rings - worn or damaged rings will allow for presssure blow-by. Look with a bore scope see what it looks like
#3 - head gasket damaged - this ususlly is evident by white smoke from tailpipe and sweet smell from exhaust, coolant lost, foam and discoloration in oil dipstick
#4 - cylinder scoring - evident by lowering the piston to bottom stroke adn look with bore scope

Do another check let the tester stay on that cylinder for a little time see if it drops or holds then go from there

offroadtrd

It held the 85psi, i had it for about 3 min may be. I will leave it for longer & see. Also if valves have partially clogged, i remember a while ago reading about a special liquid that a guy suggested using (in a different forum, dont remember where) squirt & leave it overnight, turn crank at pulley slowly few times, repeat spray & leave it for 10 or so hours again. This process will free up even stuck rings at the piston, frees valves. I am trying recall that info...if anyone knew please know let me know.
The other thing common with this 2gr as i learn from Carcarenut, is if coolant is not changed around 50k mil or 5 years the coolant bcomes so acidic that it eats gasket from inside & hence leaks coolant at the cyl heads (could be any bank). I am suspecting thats what is going on as i saw No coolant in the reservoir. I am going to look for signs of coolant leak at the head & update. Either way i guess engine is coming out. Thank you all.

Leeper

Never heard of such a thing regarding the coolant. I do lknow the radiattors on RX's tend to start leaking @100-150K miles as evident by seeing any pink or what looks like Silly String on or near the radiator.
As for removing carbon, running some SeaFoam may help I prefer to run it through a vacuum hose to assure it gets directly to the fuel injectors, cylinders versus just dumping it into the gas tank lettng it sit can only help soak and hopefully remove debris
Has your car leaked or needed any coolant? Has it maintained the proper level in the radiator and reservoir tank?
Having low compression in one cylinder in a RX is quite uncommon

offroadtrd

In addition to above am thinking of using the B-12 chemtool soak the piston rings and do an oil change.
https://www.berrymanproducts.com/que...oil%20capacity

offroadtrd

Check this video....
Yes my Coolant reservoir was empty, just bought the truck. Also adding seafoam through intake will only clean the intake, possibly fuel inj but not the rings. You have to pour inside the spark plug hole for the rings.

Mesquite77

See the YT link in this post for dropping subframe etc: https://www.clublexus.com/forums/rx-...ck-stands.html

offroadtrd

Have left 25ml of seafoam (B12 chem is ordered but no sight of delivery yet) on each cyl ydy, will drop another 25 ml again tdy with some crank movement. BTW i saw it had the u/g metal oil cooler lines, the oil changes till 2018 had been immaculate by lexus dealer it was maintained well by 1st owner, am guessing this PO ran it longer without oil changes as its evident looking with my snake camera the pistons have a good carbon deposits on them. Will update soon.

Margate330

I'm hoping for your success friend.

Please follow up and let us know how it goes

offroadtrd

As i didnt have B12 chemtool, poured 25ml seafoam on all cyl let it sit for 24 hours moved crank slightly cple of times, repeated the process again after 24 hrs. Today i put back everything & started it ran on all cylinders (had the snapon reader & was monitoring), NO misfire on cyl 3. I turned it off to add seafoam on the intake vacuum, when i restarted again cyl 3 misfire came back. Only code is P0303. I did end up buying a nice boroscope & had a peek. There was layer of carbon soot layer deposit on almost all pistons. Going to take a good look at cyl 3 again tomorrow especially to see all 4 valves closing & opening. Upon checking compression again after all this it was still 80psi at cyl 3.

Margate330

Is there a way to tell if the valves are leaking or whether it's leaking at the piston rings?

offroadtrd

Would leak down test help, planning on doing that too. Also randomly tested psi on cyl 4 & 6 the compression psi had improved by 5-10 psi

offroadtrd

On cyl 3 I found 1 struck valve thats open(exhaust). The pictures are after adding seafoam last time & hence lots of the carbon build has dislodged around in the piston /valves. So i have soaked cyl 3 with MMO till the plug thread, so it can essentially work on the open valve. The last picture shows the valve on the left remaining open. Thinking of hand cranking about four times during this 48 hr wait. I know it may not help the situation if its a broken valve spring but if its not i hope it works. Any thoughts appreciate guys. Even if valve issue resolves by this method i am hoping to do 2 more soak treatment/ crankcase Oil flush.