Exhaust coming out the valves

timesublime

timesublime

Compression Ignition
Joined
Jun 5, 2013
Messages
73
I just tried to start my truck after getting the head back from the machine shop.

It started after a while but a loud popping noise was coming out the engine. I traced it to #6 cylinder. Raw partially burnt exhaust is coming out the valves.

I checked and the valves move up and down as normal.

I am completely stumped on this one.
 
Where exactly is the exhaust coming out of the valves and what did the machine shop do to the head?


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I can't pinpoint it exactly there is so much smoke. The shop ported, o-ringed and installed oversize valves. I looked at the headgasket at the back and no smoke comes out at the interface.
 
I have been thinking that the valve seat has dropped out. It is the only thing i can fathom.
 
Is it coming out of the exhaust runner or out of the valve guides? Or back into the intake?
 
It's so pronounced that I cannot see the source other that #6. I really have a feeling that the valve seat fell out.
 
Yeah, sorry. I just caught that in your earlier post and deleted that response.

Seems like you'd know if the seat fell out unless the valve doesn't open enough to allow it to fall out completely.
 
It's more likely a piece of the seal. I'm grasping at straws here but the only way for exhaust to get in is through the valves, or a hole in the casting, right?
 
Any chance you can get a video of this? I may not be able to offer much help but usually hearing and seeing it might help others.
 
If the seat fell out then that particular valve/valves will not have the same stem protrusion as the rest, you should be able to measure or even eye ball it with the valve cover off
 
The valves are sitting at the same height and the valve lash is still the same. I pulled the turbos off and looked in the exhaust port. All the other valves are shiny and clean. #6 is slicked with oil and there are little bits of metal all over the port and the turbine of the turbo and the hot pipe. Something is f'ed in there.
 

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If you can get your hands on a decent scope you could pull your injector and take a look down in the hole. Are the metal shavings magnetic?


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It was lots of bad noises.

I ordered one of those 7mm borescopes that attach to your smartphone for $15. Going to snake it down there and look. Will check if the shards are magnetic, this would indicate the head instead of the piston?
 
Yeah any steel or cast will be magnetic. Pistons are aluminum so it won't pick them up.


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