Burnt Exhaust Valves. Ideas?

204,500 miles on my 2000, 3.4 V6. Still factory everything!

Last month it started idiling really rough (only when it's in gear).

Coded as "Misfire in Cyl 6". I changed the plugs, no dice. Plug wires, no dice. Checked the resistance on all the ignition components and coil packs, all good. Changed the Cyl. 6 fuel injector, no dice. Electrical check to the injector is excellent. I took it to a mechanic and he says I more than likely have a burnt exhaust valve and he wants $1200 to do all the valves and timing.

I can't afford to have this done and get my family Christmas too.

I've never been that deep into an engine before, but I am an aircraft mechanic in the military, so I'm not totally scared to get in there either.

ANY ideas or experience with valves, timing or what to do is greatly appreciated.

 

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Perhaps someone can post one of the technical sites to help you ?? .... With your mechanical skills, you can probably do it ... good luck man.

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Thanks for the motivation. This whole mess has me completely stressed, expecially this close to the holiday.

 

When it rains, it pours.
I would pull the heads and price out a machine shop to rebuild them.
Never heard much of burnt exhaust valves on a 200K mile engine though unless it was air-cooled.

Could they just be carboned up and not sealing properly? Does it make a chuh-chuh-chuh.... sound idling?
Compression?

 

When it's in park and idling, it does sound like it's missing. I have a cold air intake on it and if you listen to the sound of the intake "hiss" it's missing as well. Once you put it in gear, the idle becomes so rough that it feels like it's going to stall out at any minute.

 

Did this mechanic do a leakdown test and/or a borescope inspection??. or did he just guess??.

How did the plug look on #6?

 

I think he is "educated guessing".

 

No sir. It's all original.

Is it a chain or belt?

 

Did he at least do a warm engine compression check?, or put a timing light/monitor on it to see if it jumped time?

 

Is it common for the heads on 3.4 V6 to last over 200,000 miles?

Everything I hear and read says if you are getting into the heads and valves, you need to go ahead and do the timing and water pump we well. Is there any truth to that?

 

I'm going to call and ask him now.

 

NGK plugs. Nothing special, no splitfire or irridium. Just what Advance Auto said it called for in their computer.

NAPA Belden Premium 5mm plug wires.

 

He did neither.

He just said that since it's only one cylinder (Cyl. 6) that is getting the misfire, it can't be timing. He said there would be problems with more than one cylinder if it were a timing issue.

 

Visa = For when shit like this happens

All serious though, Good luck man besides replacing plugs that the depth I've gone into my engine

 

I'm not sure what that means.

However, the problem existed prior to the plug change and developed over the life of the previous set of plugs.

For what it's worth, I do remember the guy at the counter being suprised at the fact that the truck only calls for a "cheap" plug.....

The old and new ones are

$6 BKR5EKB-11 NGK Spark Plug Stock # 3967

BKR5EKB-11