P0420 and P0430 - 2006 LC

[RECRUISER]

With your good baseline numbers already established it will be interesting to watch for changes that occur / to compare.
Use dialectic grease on the new spark plugs when you install. Looking forward to seeing the new numbers.

 

[2001LC]

I've recently pick up an 07 LC, no check engine light and runs fine.

While inspecting engine bay I notice gunk build up on outside of each lower intake ports. Both head cover seals look tight so I don't think much if any oils coming from them. I've seen this on every (only 3) VVTi plastic intake I've seen. Anyone else notice this?

I pulled the intake manifold last night. I actually remove bolts a few days ago, then let it sit until I got back to it. I did lift an let sit back down several times while pulling off (hung up), but never past the guild studs. So each time it would settled in same spot. When I did final pull the manifold I notice what may be leaks. Noticing how much oil is in area, I assume is from PCV valve. I'd consider this normal but it could be why intake ports collect so much gunk on outside of ports. By this I mean as engine cools over night oil seeps out seal of intake to head gasket. The head & intake mating surface are very oily outside gasket seal area. But I did not get off quickly or in one smooth move, so not conclusive.

What do you guy's think this is sign of leak?
Did Toyota design this as expectable?
Does the intake plastic expand with heat like the metal of the heads?
Could this have anything to do with issues (P0420 & P0430) you're seeing?


Port #3 and #6 looks like possible leaks at operating temp. I say this because of blackness of gasket on outside. Could these be clues of intake leak(s). Although #3 & #6 could indicate when at operating temp as well, or may just be from my pulling off carelessly. I think this warrants a vacuum test when cold as well at operating temp, on those that have not replace intake gasket. Not sure how good a test would be cold with RPM so high, or how you'd do that.

These extra black could be from my sloppy removable, but keep in mine it settle in same spot each time. So I don't think any grim not already there was introduced. So very like it was there before I loosen bolts & pulled on intake.

If there is a next time, I'll pull off fast in one move.

 

[2001LC]

Next morning after sitting on paper towel to dry oil. Notice #4 looked a bit funny also.

 

[2001LC]

Here one more thing I just found, while testing thermostat on bench. It only opened 9mm not the 10mm required at 203 degrees in boiling water. Unfortunately I didn't tap into tech stream and get reading first. But Temp gauge and cabin heater seem to work normally. Although gauge was not at 45 degree more like 44 degree at operating temp. This is same as my 01 gauge which sets just a hair below center peg (44 deg)

I pulled my 01's thermostat and found it was only opening 8.5mm.

I replaced both yesterday and will be replace radiator caps next, 10 & 16 years it's time.

 

[2001LC]

Follow-up. I suggest every 2006 & 2007 replace intake manifold gasket if gunk is seen on lower end intake plums and around intake head ports.

I found gunk on 172K 2007 LC. Gunk was interesting to me on first inspect with engine cover off. Now I'm sure where oil came from.

I replaced the gaskets (intake & throttle body) and found some interesting things:

The new intake to head gasket is installed with old in bag in below picture:

You can see the design is slightly different with old squared edge and new has raised tapered ridge running through center

Old measured 5.05mm.

New is 6.82mm thick... Did old shrink & compress or was replace made different & thicker or both?

Old and new Throttle body design looks the same. But you can see old is 5.83mm, ~1.1mm thinner than replacement.

New Throttle body gasket is thicker at 9.92 and beefier, why?

Regardless of why difference in thickness the old intake to heads' were leaking. Old's were soak with oil, as was outside of intake plums & head port area both outside and underside.

Go pull the engine cover offer your VVTi with plastic intake. I'll bet you find gunk built up on intake plums near lower end. If oil leaks air certainly will.

I'm putting inspection gunk, replacement of intake gasket as PM on VVti 2006-07 in my spread sheets. Key will be when gunk builds on lower end of intake plums.

Can intake air/vacuum leak be contributing factory in damaged CATS?????

 

[KYLandy]

Great info! I will pull my engine cover and see if there is gunk in those areas. Maybe I am lucky. My LC was thoroughly maintained at the dealer, though, so that might make a difference. It's strange that there is no filter in the PCV system on the LC. My 1997 F350 has a filter for the PCV system right before the air goes in the airbox. There is a prefilter for the PCV right before it goes through the airfilter box and into the intake.

BTW, I installed the URD O2 simulator on my 2006 LC yesterday and so far so good. It does not solve the problem of the bad cats but hopefully I won't have to keep clearing the codes. It did make it run better, though, and that was a surprise. It seemed to take away the slight hesitation I had when taking off quickly. The engine seems more responsive now. Maybe my gas mileage will improve, too.

The reason I went ahead with the O2 simulators is because I would rather spend the money on something I really need, like tires and skid plates, instead of on cats. Someday I will replace them with OEM pipes but not before I equip my LC for some mild off-roading. This means I can be obsessed with tires now without worrying about those P0420 and P0430 codes.

 

[2001LC]

I spoke with Toyota shop Foreman on CAT issues. He said they do a coolant system leak down test over night. That a short term test doesn't always reveal a coolant head leak, and that antifreeze is number one killer of CATs.

FWIW: I found this intake gasket leak because of coolant leak at gasket of head to front water bypass joint. All though that's not a head gasket leak, I could see where coolant could enter through intake to head gasket from outside along the two. Even assuming both leaks only accrue when engine cold (heat expansion possibly seals) drops of coolant may enter when engine cold. The coolant bypass gasket set about 1/2" below intake to head gasket, and leak tended to run out/off front of engine. But when I parked front up hill the pocket filled and coolant ran out/off back of engine.

I'm not saying this is cause, but vacuum leak be contributing factor, and coolant leak into heads from intake gaskets when engine cold would throw cold coolant into cat on start up. Over time small drops can kill CATs or so Foreman stated to me.

 

[KYLandy]

Can you point me to where the coolant is located in the first photo? I want to check that exact spot. I mentioned before that I thought I might have a very small coolant leak. I'll check my coolant level since I topped it off last time and see if it has moved. It makes perfect sense that a coolant leak could be the problem on mine. My cats aren't plugged or restricted in any way that I can tell so, logically, they must be poisoned by something. I have always thought that to be the case. It would also explain why the Cataclean had no effect. If there was carbon buildup on the cats, the Cataclean should have been able to help clean them up so I can rule that out. I used 3 bottles and they made no difference.

I see that it has 178k miles on the ticker. Do you know if the TB was ever changed? I know they usually do the water pump when they change the belt.

 

[2001LC]

In picture above, in lower left corner, you can see a small pool of Toyota Red antifreeze (proper would have been Toyota pink for this 2007) . This is the front of the engine. You'll notice serial number on block, which is under where the throttle body sits. You can also see the bad water bypass joint gasket that needed replacing on left, whereas the bypass gasket on right was in good condition. I've no explanation for the gasket going bad.

There are two water bypass joints, a front and a rear. At each end of bypass joint you'll see two nuts. The gaskets are under those spots, there are four gaskets in total. The green arrow is where my leak was.

It has 172K miles on the ticker. T-belt & water were replaced at ~93K miles.

 

[RECRUISER]

Great find here. wanting to bring a point up for discussion and see where this takes us. Since your coolant leak is on bank two, that could very well explain the cat code for bank 2 (P0430).
Bank one won't be poisoned by bank 2 is my understanding, just wanted to Think this through with you as we have both p0420 and p0430 codes .
Great work 2001LC.
I will update you on my progress in a future post as currently both my Codes went off by themselves this time after replacing my spark plugs and PCV valve and running a bottle. Of cataclean through.

 

[2001LC]

Great find here. wanting to bring a point up for discussion and see where this takes us. Since your coolant leak is on bank two, that could very well explain the cat code for bank 2 (P0430).
Bank one won't be poisoned by bank 2 is my understanding, just wanted to Think this through with you as we have both p0420 and p0430 codes .
Great work 2001LC.
I will update you on my progress in a future post as currently both my Codes went off by themselves this time after replacing my spark plugs and PCV valve and running a bottle. Of cataclean through.

To be clear: I did not have a CEL on this 07 w/172K on clock, and to my knowledge CAT(s) are factory.

This 07 is new to me, and I'm in process of restoring to factory spec. It's my first VVTi, and as with all 100 series I work on or restore, I look for cause of issue(s). I find most issue with these rigs, comes from improper maintenance procedure. That is; not following PM schedule or doing work improperly (number one: wheel bearing, second: lubing, third: coolant system). In this case improper coolant system service is for sure an issue, but no signs of overheating, just not factory SSL pink in the system which points to improper flushing interval. But that doesn't explain this coolant leak definitely.

But the issue of intake manifold gasket leak has nothing to do with maintenance, it is a design issue without a doubt. I've no doubt if oil leaks out (which may or may not be, only when engine cold) air, oil and water can get directly into head through intake ports.

Toyota Engineer's do design with heat expansion in mind, but they don't intentionally design in a leak.

 

[RECRUISER]

This thread is getting long but I did want to update everyone with my P0420 and PO430 codes.
I reported that both lights went off by themselves and stayed off for about a day and a half of driving earlier this week but then came back on again. This morning (after 2 days of being on) I got in and started it up and all 3 yellow CEL dash lights went off after startup cycle. So good things are happening. PLEASE NOTE THAT THE CODES STILL APPEAR IN THE VEHICLE STORED HISTORY SECTION But they are not pending and have not been manually erased. SNAP ON SOLUS EDGE SCAN TOOL. I drove all day today with about a dozen starts and stops all with no CEL appearing OR GOING TO PENDING STATUS.
So now that I have new spark plugs and PCV and cleaned the mass airflow sensor and put a new air filter in and cleaned my battery terminals and put a bottle of Cata-clean in, I am seeing signs of the problem correcting itself? Hopefully the cats are cleaning themselves and because I had a problem with my spark plugs being so degraded and out of gap way to wide and my PCV was gunked up, hopefully this has corrected the dirty exhaust heading to the cats.
I will post again in a month or so but if you are experiencing this problem in the meantime I would at least do all the p.m. work that I have described and maybe you will find your problem before having to go to the expensive option of changing oxygen sensors or catalytic converter's.

 

[KYLandy]

That's good info. I was wondering if the CEL lights would ever "go out on their own". My lights seem to come and stay on until cleared but my problem is likely more than just carbon buildup on my cats. I received my pressure tester for the cooling system the other day and will do an overnight leak down test to see if there are any issues. I post results when I have them.

So far, the URD O2 simulator is keeping my lights OFF. It is so much better to drive now without seeing those lights. Part of me still knows there is a problem but taking the "ostrich approach" might help me live longer.

 

[RECRUISER]

Love the URD O2 simulator idea. I say don't sweat the small stuff at the end of the day. Fight the big battles. Drive and enjoy the big Toyota is what I say.
My CELs came on again this morning first thing and then by mid-morning they turned themselves back off again so I'm continuing to see progress. Earlier this week they stayed on for 2 days before going back off by themselves. So regardless I'm convinced my engine is running clean and that's the most important thing if I need to I can put a dark cover over the check engine lights with a clear conscience. Truck runs great. Engine scans looking better.

 

[KYLandy]

I wanted to also follow up with my coolant system pressure test. I received the kit last week and did the test today. The first test was the static test. I took this reading after about 2 minutes. The cap says 108 kPa which is about 16 PSI so I pressured the system, according to the instructions, to the yellow arrow:

This reading at about 10 minutes:

And this reading at about 15 minutes:

So, it looked like I had a small leak but it could have been the cap or hose leaking somewhere because I could not find a leak anywhere. I checked every part of the coolant system several times but could not find a leak. The manual says that if the pressure drops to run the dynamic test. The test starts by connecting the tester to a cool non-pressurized system and starting the engine. If the pressure climbs immediately or rapidly, then it would indicate a possible crack in the block or a bad head gasket. It did not exhibit any rapid climb at all but slowly climbed over a few minutes to maybe 7 PSI. If it does not exhibit these characteristics, then manual says to pressurize the system to the recommended pressure on the cap and observe the pressure. If the needle fluctuates rapidly, then it would indicate a small cylinder leak. It was as steady as it could be with zero fluctuation.

I am satisfied that there is no internal coolant system leak and the tiny drop in pressure I observed was due to the hose or the testing system. Interesting enough, I ran the static test 3 times and on the the 3rd test, it did not drop at all after 15 minutes. Before the third test, I checked all hose connections and tightened everything up, so I believe it was the testing system and the the coolant system. This means I still don't know why my cats went bad but I'm sure it was not a coolant leak.

 

[2001LC]

That's good. BTW: A shop foreman said they run coolant system pressure test overnight. I'd not heard of that before, but sounds interesting.

 

[2001LC]

Here is the one I removed

View attachment 1344095

Does the greenish color look unremarkable to you?

 

[looking4lc]

Does the greenish color look unremarkable to you?
View attachment 1432893

i was told that could be because of the fuel system additive i used few times.
since i keep getting P0430 code, i am planing to soak both front sensor with contact cleaner for a day and clean them well since they are hard to find over here.
code appears once in 2 weeks and sometimes next day after reset.

any suggestions ?

 

[2001LC]

i was told that could be because of the fuel system additive i used few times.
since i keep getting P0430 code, i am planing to soak both front sensor with contact cleaner for a day and clean them well since they are hard to find over here.
code appears once in 2 weeks and sometimes next day after reset.

any suggestions ?

What color is your coolant?

Do you have gunk build-up on your intake manifold ports on lower half like I (pictures)?
Pictures!

 

[looking4lc]

What color is your coolant?

Do you have gunk build-up on your intake manifold ports on lower half like I pictures?
Pictures!

always Toyota red coolant.

i don't think i have gunk build up on manifold as i am very cautious for any leaks. i will check tonight and take some pics.
Also, i will clean and swap the the front sensors (air fuel sensor) and see if the code moves.