Burnt Valve?

It was a pretty good explanation so far from them. Impressive actually. Was it running weird?

 

Not really, but the check engine light when on the day before my scheduled service when I dropped off, so I didn't have much time to observe. That being said, the truck always idled pretty low and had a "diesely" sound to it, but thought it was normal, since it was from day 1 and typical of atkinson engines.

 

What proof did they offer that your mods caused this failure? Because THEY HAVE TO PROVE that your mods caused the problem not just say no cuz mods!

 

I asked and that’s when they decided to get corporate involved, either way, I got a better vehicle out of the deal and a $1000 check from the dealership due to the trade difference because I’m a negotiations pimp.

 

But your build was badass.

 

The 4Runner is getting there...

 

Definitely. You're doing it right.

 

Like a Boss!!! Very Nice.

 

Nope. Answer is, they (the tech) don't care. And why should they, pays the same. Nothing extra ($$$) for actually figuring out the "why".

 

Trucks all done. Will be picking up tomorrow AM. Below is the final notes once they began the work (prior diagnoses notes earlier in thread):

***CUSTOMER AUTHORIZED TO PERFORM ENGINE TEAR
DOWN 4.21.20 AT 8:20AM*** . REMOVE ENGINE FROM TRUCK AS PER R/M. TEAR ENGINE DOWN . INSPECT R/H CYLINDER
HEAD B1 . PULL OUT EXHAUST VALVES FROM HEAD WITH SHOP FOREMAN . INSPECT . FOUND CYLINDER 1 BOTH EXHAUST VALVES
ARE MAKING POOR CONTACT WITH VALVE SEAT . AND MOVEMENT IN VALVE GUIDE WITH CARBON PRESENT . SPOKE WITH FTS .
CREATE A TAS CASE WITH TAS # XXXXXXXXX . SPOKE TO TAS . THEY SUGGESTED REPLACE B1 CYLINDER HEAD WITH ALL 4 VALVES
TO BE REPLACED IN CYLINDER 1. ALSO CYLINDER HEAD VALVE GRIND KIT . WITH NEW REPLACEMENT CYLINDER HEAD . BUILD
ENGINE AS PER REPAIR MANUAL .WITH GASKET KIT . REINSTALL ENGINE AS PER REPAIR MANUAL . ALL CRITICAL FASTENER ARE
TORQUE TO R/M SPECS . REPLENISH FLUIDS . PRIME / START MOTOR LET RUN . ROAD TEST .

 

@alexwlkr32 Thanks for the update and glad to see your truck is done! Did they ever provide a reason or diagnosis of what caused the valve operation failure?

 

Wow.

Haven't had to pull a motor to get a head off since working on a 429 Cyclone CJ!

 

I wonder if this is a port injection issue.

 

Report also said .... ".... AND MOVEMENT IN VALVE GUIDE WITH CARBON PRESENT ..." Bad / soft valve guide premature wear caused alignment/wear problems with valve seating ??

 

I was half thinking carbon build up on the stem cause guide wear. Idk how the injectors are set up though

 

I was thinking the opposite. Valve guide issue causing the valve not to close (burning it) and letting air by causing the carbon build up?

Injector has nothing to do with it since it would be on the intake side.

Edit: Wonder if's an oiling issue to those guides. Weird in the few cases it's happened it's always been #1.

 

Well if the injectors wasn't cleaning the valve deposits it could Get between the seat and burn the valve. Idk how likely it is that it would only happen on cylinder one though.

 

These are the exhaust valves. No injector to clean them. Only the intake said has an injector.

Wonder if it's oiling issue to those valve guides causing them to wear.

 

Derp. I totally missed that part!

 

Long time tech here and bad valve guides or burnt valves on direct injected engines happens more often than you think. The nice thing about GDI engines is you get power, economy, reduced emissions and so on. The high pressure fuel system and direct injectors are highly sensitive to fuel supply or injector malfunction and when these engines are running at part throttle or cruising conditions the can be run super lean. Unfortunately if a cylinder isn’t running perfectly it’ll over heat a valve seat or valve guide and you’ll end up with a burned valve or a wobbly valve guide. Happens on a lot of the European cars I work on.


I’ll usually have the head redone at a machine shop but unfortunately dealers can only fix the car how ever Toyota supplies the part, which in most cases is “it’s bad, throw a new head on”. The nice thing about dealerships is what ever work they do is covered nation wide so that’s cool. Where for shops like mine, the warranty has to be done through me.