Broken Intake Valve from Valve Float 6.2L L92?

[Lsnoob13]

Ok, so i decided to go ahead and take the heads off since i was thinking of all the "guesstimation" that would have to be done. ive been slowly been chopping away at it after getting off work. i have so far gotten the intake off, unbolted the headers, and im currently disconnecting the exhaust. i so happened to disconnect the part that has the flex pipe and a large glob of milky oil landed on my arm.....so im guessing that the end culprit is a head gasket maybe im not sure. i will continue to work at taking the heads off i will post pictures as i go.

 

[Lsnoob13]

Your compression test gauge should be able to be used to add air to that cylinder. Hopefully it looks something like this...

View attachment 202700

You can use a small tire inflator but a portable air tank would be better because it won't make noise like a small compressor will so it would be easier to hear air escaping through the intake or exhaust.

You could also get a pressure tester for the cooling system and pull the spark plug on cylinder 8. Apply pressure to the cooling system and see
A. If it holds a constant pressure for a period of time and
B. If you get coolant in cylinder 8.

This would probably require plugging the overflow on the reservoir in order to build pressure.

Also it may not reveal everything because, as mentioned before, somethings only show up when up to operating temperature.

Checking it with the coolant system pressure tester may not reveal a bad head gasket if it isn't bad going to the water jacket.

Also checking it that way will not tell you if you have a burnt valve, obviously.

So i pulled the heads. Everythi g looks good except for the obvious culprit cylinder 8. The valve was coated.....no it was CAKED in carbon build up. So im guessing it was not sealing properly. So what are my options now? What could have caused that? So that i may replace it and get my truck back running...its been too long.

 

[randeez]

when you say caked - are you talking about in the cylinder the face? the back of the valve in the runner? or on top of the head in the spring?
intake or exhaust valve?

you will probably need to get the heads cleaned up and maybe a valve job if you're worried about it sealing

 

[Lsnoob13]

when you say caked - are you talking about in the cylinder the face? the back of the valve in the runner? or on top of the head in the spring?
intake or exhaust valve?

you will probably need to get the heads cleaned up and maybe a valve job if you're worried about it sealing

The exhaust valve was caked. What could have caused this? Also could this have caused my missfire and smoke??

 

[kbuskill]

The exhaust valve was caked. What could have caused this? Also could this have caused my missfire and smoke??

View attachment 212661 View attachment 212662

I assume it wasn't just one valve that looked like that.

Could be partially due to the PCV system allowing oil into the intake.

Yes it could cause hot spots in the combustion chamber which could cause preignition/misfires.

 

[randeez]

What's the intake valve look like for the same cyl?
On the back of an exhaust valve caked up like that would usually be a valve seal/guide problem. But the front caked also make me wonder if the cylinder was firing at all or extremely lean.
And doesnt look like it was seating against the head very well

 

[gpracer1]

That looks like the cylinder was dead for a long time.
My first car I bought back in 86 was a Nova that was running on 7 cylinders for a while due to the previous owners negligence , the intake valve push rod and lifter on that non firing cylinder was junk.....looked just like that.
Could also be no spark or bad compression, etc.

 

[Lsnoob13]

I assume it wasn't just one valve that looked like that.

Could be partially due to the PCV system allowing oil into the intake.

Yes it could cause hot spots in the combustion chamber which could cause preignition/misfires.

Actually it was the only valve that looked like that the others looked normal. Even the intake on the same cylinder looked good no build-up here is a picture of the intake valve from the same cylinder.

 

[kbuskill]

Actually it was the only valve that looked like that the others looked normal. Even the intake on the same cylinder looked good no build-up here is a picture of the intake valve from the same cylinder.

View attachment 212774 View attachment 212775

Weird.....

 

[thompsoj22]

what does the stem seal for that valve look like? how does it compare in feel/appearance to the others? is the valve guide for that valve loose? and look for cracks around the casting where it is pressed in. keep it simple and cost effective. it just seems isolated to that specific valve as there are no deposits in the combustion chamber which rules out piston/rings/pcv? and yes that was your smoke and misfire, That was a sick cylinder and could not have had much compression. if the coil hasnt been checked i would measure/check the resistance and confirm it wasnt bad also?. as someone else said, Weird?