I told ya I'd drive home a PRO over this! 2 cylinders failed leak down test. Only 16K miles.

UPDATE....
OK, went by the Dealer yesterday afternoon. I finally got to talk with the Tech and see what the final verdict was.
Seems we have a machining issue with the cylinder heads. The valve seat machining is not done correctly on some heads.
And this does not allow the exhaust valve to seat properly. Said he'd seen this on about 7 different occasions.
5 on the passenger side and now mine the 2nd of the drivers side cylinder bank.
He said they do a test with constant a amount of compressed air. And check for the amount of air the that escapes or leaks out.
9% or less is considered acceptable. He said #2 cylinder failed with 10-11% leakage. And #6 was at 20%.
Said this machining issue eventually allows exhaust gases to wear/burn away at the valve letting compression by. Thus casing the
misfire and the engine codes. He said they checked the other cylinders and they were found to have no issues at this time. So it appears
to be limited to this 1 cylinder head. So boys! We're getting a new cylinder head and valves! He said if nothing goes wrong. I should get the truck back Tuesday of next week.




You can see where the exhaust has be going/blowing by the valves.

 

Thats great dude! You definitely have a case for some goodwill warranty.

 

Right on congratulations justice

 

Great post! Well not great for you but it's nice to know what is actually causing this issue. It's not a design flow but a manufacturing defect. I figured it had to be something letting exhaust by since that's almost always how you burn a valve. But wasn't sure if something was making them hang open or a valve not sealing.

I may do a leakdown test around 55K or so on mine just to make me feel better before I'm out of warranty.

 

Thanks, and not a bad idea on the 55K test.

 

Free extended?

 

Here's the "Official" diagnosis.

 

Did they have fender covers on this time? Or did you not get back to where the truck is?

 

Yes, sometimes Toyota goodwills them I got one on my 16 after 2 rear diff replacements.

 

Definitely worth an ask.

 

I wonder what the timeframe was on the 7 motors he has seen with this issue? If its a short period time that could be pretty concerning.

 

On the phone with Toyota now! Case #2208********

 

What color Pro are you asking for?

 

Army Green! $100 says I'll drive home in one!

 

Sounds like they used a differential type compression test where leak is compared to a reference orifice. If so, you would need to know the test specs to get reliable results. I’d get a bore scope after it. When valves aren’t seated properly, heat conduction isn’t even and they’ll develop visible patterns of burning before actually leaking. I’ll add photos later of what valves starting to burn look like. You can buy Bluetooth scopes to use with your phone these days for less than $200 that work better than my high dollar snap on from a couple years ago

 

Yeah, I'm familiar with leakdown tests and have done them before. Years ago on a 99 Cobra that was down on compression in one hole I used a ghetto version of it. Used the adapter from a compression tester hooked to an air compressor to find our where the leak was coming from. Could hear and feel the air coming out of the exhaust even though the valves should have been closed.

Was fun pulling the heads off the car, having it rebuilt and timing the cams again. But it started right up and ran great after that... this was from being run out of oil though and not a defect.

 

This is all very educational, and thanks for the explanations that don't get overly technical. I wonder if the mechanic is able to relay back to corporate engine identification for these failures. Surely Toyota would be able to identify where these heads are being machined, would they not?

Yeah, that's what I'm wondering. If this one master tech is seeing evidence of seven...

 

Yes, I made it back to the truck. I took the pictures of the the cylinder head.
And nope, no covers. But not working on the truck at the time. They were warned either way.

 

I'll ask him about the time frame of these when I see him again.

 

very interesting.