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Interestingly enough… Cylinders 7 & 8 also see the most of engine oil leaking / seeping through the spark plug tube channels seals..
Joe Z
Glad you brought this up as I too had this very problem. I had always figured this happened from years of overfilling before I bought the car May 1st 2014.
Originally Posted by Faaith
i see about 3-4 cars with the same isssues on intake titanium valves
only on 7-8 cilinders. all of them have primary cat, plate leaks. and 1-2 temperature damaged direct injector on the same cilynder
to my mind this problem because of overheat.
never seen bad clearences on isf at all, except for those already burnt out https://www.youtube.com/watch?v=Jkiw6XtgrcQ&t=3s
Great work & great video. What are theories as to why this type of overheating only impacts 7-8? And do you have any additional opinions on the tube seal issue being related?
Even though my car has yet to suffer from the valley plate leak, I can't speak for any overheating before May 2014 and again, my car suffered from tube seal failure. I'd imagine tube seal failure impacts oil pressure & could lead to starvation. Just curious why all of this seems to impact 7-8.
Glad you brought this up as I too had this very problem. I had always figured this happened from years of overfilling before I bought the car May 1st 2014.
Great work & great video. What are theories as to why this type of overheating only impacts 7-8? And do you have any additional opinions on the tube seal issue being related?
Even though my car has yet to suffer from the valley plate leak, I can't speak for any overheating before May 2014 and again, my car suffered from tube seal failure. I'd imagine tube seal failure impacts oil pressure & could lead to starvation. Just curious why all of this seems to impact 7-8.
I think they are VERY much related… I always monitor plugs 7 & 8 for oil..
Oil in the tube channels, spark plugs, coil pack all add up and for sure in the video you can see burnt up oil is getting onto the tops of the combustion chambers…
Overfilling and the force of gravity slush the oil to that top back wall of the engine.. If your tube channel seals are going bad, they will see the most seeping..
I now only add 9 qts start run stop.. wait and then top off to the 2nd dot of the dipstick, on my OCI.
Have you seen this issue on any cars without cats? and can you tell if the injector has had temperature damage without pulling them out?
direct injector didnt work at all on problem cilynder. we have million missfires on this cilynder..when i choose port injector wia techstream engine works well... after replecing direct injector i see lot of carbon on it. plug destoyed by temp
first i did after my statistic - buy ppe headers, and use composite heat shields thermal division over runners , over mounts and new starter
and now i often see 2 bars oil temp when a\c on when car in drive condition... 2 years before-never see 2 bars in drive etc always was 3 bar (2010year)
yes. our primary cats overheating engine block/oil i see
I’ve never seen oem cats in an ISF, but from looking at oem headers, I’d wager the cats are pretty close to cylinders 7 and 8. Now I’m glad the previous owner had PPE headers on mine very early in its life.
I’ve never seen oem cats in an ISF, but from looking at oem headers, I’d wager the cats are pretty close to cylinders 7 and 8. Now I’m glad the previous owner had PPE headers on mine very early in its life.
i appoligize I kept saying exhaust valve but meant to say intake valve.
Also just to clarify, there was no clearance on that valve with the seat eroded like that, which is why it experienced compression loss. Just removing the shim to test improved compression to 170-180psi.
We haven’t seen any heat issues on valves, even on supercharged engines.
Regarding valve clearance, I’m just suggesting that for NA higher mileage engines seeing lower compression, checking valve clearance to see if there is correlation would be interesting!
Rafi
It stands to simple reason there was no clearance on that valve with the seat surface so completely eroded. These are solid lifter engines, not hydraulic, so once the valve starts losing metal, it's going to be tight. I don't believe it was tight and that lead to the loss though. I know exactly what that looks like, and this valve isn't what I've seen when valves were improperly adjusted. There's something else going on here for sure.
I've checked my valves twice and I'm coming due for a third check. The 2008MY recommended service includes a valve inspection every 60k miles. This disappeared in 2009 for no obvious reason besides cost. I still think it prudent to do routine lash inspections and this valve problem is a solid reason why I will continue to do these checks. It's pretty easy to tell a tight valve especially if you have the previous clearance documented. Intakes have all been within spec and have not changed during my ownership. Exhausts have gone toward the loose side of spec, with one at the limit of loose. I'm pretty confident if I did some top speed runs (full load for 10 -15 seconds) and ran some water through the engine, those valves would tighten up because (more than likely) the factory spec'd wide seats on the exhaust side and they've got some carbon build up that would burn off under heavy load. I didn't do anything to adjust this valve the last time I checked for this reason. I also have experience adjusting a "loose" exhaust valve on one of my own machines and from this developed the belief that a loose valve is a happy valve. It was an expensive mistake.
2JZ-GTE engines also had a propensity for damaging the rear cylinder, but this was a result of an external EGR system that bled right into cylinder 6 and had a cooling chamber right behind cylinder 6. Everyone who has experience with these engines disables EGR to prevent this damage. Since the 2UR-GSE doesn't use an external EGR system, but uses variable cam timing to invoke the same response, it's hard to blame an EGR function without some corroborating evidence. From the Moscow video, even more frustrating is, the damaged valve is all the way at the back and sits right next to an undamaged valve. There's nothing intuitively obvious as a direct cause, and engines like mine with 190+k miles running perfectly don't make this any easier to directly diagnose.
Sound like we've found a real weakness in the engine besides the propensity for cracking ring lands.
It stands to simple reason there was no clearance on that valve with the seat surface so completely eroded. These are solid lifter engines, not hydraulic, so once the valve starts losing metal, it's going to be tight. I don't believe it was tight and that lead to the loss though. I know exactly what that looks like, and this valve isn't what I've seen when valves were improperly adjusted. There's something else going on here for sure.
I've checked my valves twice and I'm coming due for a third check. The 2008MY recommended service includes a valve inspection every 60k miles. This disappeared in 2009 for no obvious reason besides cost. I still think it prudent to do routine lash inspections and this valve problem is a solid reason why I will continue to do these checks. It's pretty easy to tell a tight valve especially if you have the previous clearance documented. Intakes have all been within spec and have not changed during my ownership. Exhausts have gone toward the loose side of spec, with one at the limit of loose. I'm pretty confident if I did some top speed runs (full load for 10 -15 seconds) and ran some water through the engine, those valves would tighten up because (more than likely) the factory spec'd wide seats on the exhaust side and they've got some carbon build up that would burn off under heavy load. I didn't do anything to adjust this valve the last time I checked for this reason. I also have experience adjusting a "loose" exhaust valve on one of my own machines and from this developed the belief that a loose valve is a happy valve. It was an expensive mistake.
2JZ-GTE engines also had a propensity for damaging the rear cylinder, but this was a result of an external EGR system that bled right into cylinder 6 and had a cooling chamber right behind cylinder 6. Everyone who has experience with these engines disables EGR to prevent this damage. Since the 2UR-GSE doesn't use an external EGR system, but uses variable cam timing to invoke the same response, it's hard to blame an EGR function without some corroborating evidence. From the Moscow video, even more frustrating is, the damaged valve is all the way at the back and sits right next to an undamaged valve. There's nothing intuitively obvious as a direct cause, and engines like mine with 190+k miles running perfectly don't make this any easier to directly diagnose.
Sound like we've found a real weakness in the engine besides the propensity for cracking ring lands.
Is that weakness randomly ruining valves with no real known etiology, or the random oil soaked plugs?
Last edited by Jwconeil; Dec 24, 2021 at 07:14 PM.
The valve seating surface is damaged which is why the cylinder won't hold as much compression. The head will likely need machine work. If you look at the pics you can see the damaged valve's seating surface kind of has a "concave" shape to it from it beating itself into the valve seat
correct. Question is why that happened. It didn’t happen overnight. We did not notice any defect of the valve seat. That leaves possibility of a defective valve or excess clearance from factory causing this issue.
Originally Posted by Quadrphnia
It's absolutely fascinating.
RRRacing - have you seen this beyond this one customer? Based on what I've read here (and your superior knowledge of this vs my own), this should be RARE. Tight seems akin to some Hondas but this is the first I've read on the forum about this.
All I’m saying is that we are seeing low compression numbers reported on some high mileage cars, one of the explanations might be similar issue to this, to one extent or another (this may be an extreme example)
Originally Posted by LeX2K
Did you measure the clearance? Too little clearance doesn't make the valve "pound into the seat" it reduces the time the valve contacts the valve seat which increased heat and causes eventual damage.
It had no clearance at all, but that is to be expected when you see that much erosion on the intake valve.
