Help Diagnosing Engine Knock

oconnef

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@pagrey @Harcust @The Goblin

First, thank you for all the information in this thread. I'm a stubborn guy, so "the noise" is bothering me, but it's not my primary concern...yet.
I have a misfire in cylinder 1 that's been bothering me for months. Replaced plugs, coil rail, switched plug cylinders, switched fuel injector cylinders, and other "cheap stuff". Coincidentally (maybe), I also was getting CPS and CKPS engine codes for a bit, but ended up replacing the OPDA after noting a lot of "play" in the wheel. All codes went away but the haunting 301.
I'm here on this thread because I've noted that several forum posts and youtube videos have showed that misfire can be caused by pushrod/lifter/rocker arm issues...
Anyhow, noting some carbon fouling on the plug for #1, I tried a compression test(dry) and found 65psi for cylinder one. All others were at or above 120psi, and within tolerance of each other. I'm doing a wet compression next and leak-down, but wondering if anyone else with "the noise" also had engine codes relative to misfires?
I don't want to go tearing down the engine to fix the misfire code, intriguing as it is to fix the noise. Really just trying to get her back in shape so that it'll pass smog check.
It's probably worth noting the engine has 276k miles on it. Pretty well kept other than the dusty conditions of California desert seem to exacerbate squeaks and rattles here and there. Not to get off topic on this thread, but wondering if anyone else was seeing misfire codes? Also, IF I do decide to tear into the engine (if a burnt valve or something major is causing the issue), should I go ahead and do lifters, pushrods, chain, etc like with a CompCams kit? I mean, if you're going to the trouble of getting that far into the engine with that many miles, is it better to just go ahead and redo those elements?
 

oconnef

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Update: did the cheapest test of all - the paper over the tailpipe test. Definitely sucking the paper back in, which seems to indicate a stuck exhaust valve? Can anyone verify this? Should I bother with the leak down at this point or just pull off the valve cover and visually inspect. I'll update as I go along...
 

pagrey

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Without reading over the thread again have you done the Jeep de-carbon deal basically pouring water in the intake? I think Jeep even has some special mix you can use. Sometimes the value can stop spinning and start leaking. I might look into that before tearing the thing apart.
 

oconnef

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Without reading over the thread again have you done the Jeep de-carbon deal basically pouring water in the intake? I think Jeep even has some special mix you can use. Sometimes the value can stop spinning and start leaking. I might look into that before tearing the thing apart.

I've heard of using a very small amount of SeaFoam before, but not the water method... I had to look it up, but does this sound about right?

I'm certainly game to try it.
Is there any use in going further *before* this cleaning? I don't know for sure if the valve is burnt, bent, or other some other mystery cause, but I assume this cleaning couldn't hurt anything...
I can attach some videos if need be, but based on the thread, I think "the noise" is a side issue and not sure what anyone would gain from seeing the paper flapping back into the tailpipe intermittently.
 

oconnef

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That's the idea, water bottle with a hole punched in the cap I've heard.
Tried this but didn’t see any white smoke or anything.

I pulled the valve cover to check a visual of the sticky spring or whatever and the engine wanted to run away revving so I cut it off. Did I miss a step? Or is the answer there?
 

pagrey

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I pulled the valve cover to check a visual of the sticky spring or whatever and the engine wanted to run away revving so I cut it off. Did I miss a step? Or is the answer there?
That's doesn't sound right, I can remove my valve cover cap and the idle is steady. Are you sure you didn't leave the vacuum lines disconnected? I think the elbow on the rear of mine has a metered hole that needs to be there so it doesn't just leak. I don't know how the water deal is supposed to go, can't help with that. I think there is a procedure to push in and rotate the sticking valve somehow but I forget the details if the water didn't help.
 

oconnef

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Nvm. I’m an idiot. Forgot to plug return hose on throttle body manifold.

Doesn’t look stuck tho…
 

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pagrey

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I'm not wording this right, the actual valve under the rocker is supposed to spin everytime the valve goes up and down so it seats in a different spot inside the combustion chamber on the valve seat. It's not easy to see if the valve is spinning correctly but if it doesn't it can burn the valve seat. Your video just shows the rockers working normally.
 

oconnef

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I'm not wording this right, the actual valve under the rocker is supposed to spin everytime the valve goes up and down so it seats in a different spot inside the combustion chamber on the valve seat. It's not easy to see if the valve is spinning correctly but if it doesn't it can burn the valve seat. Your video just shows the rockers working normally.
My bad… I’m an amateur at this depth. Is there a way to test/see that without pulling the head? I’m on the street outside my apartment so unfortunately not the best conditions this or any type of deep work.

I guess I’m still unsure it’s a stuck valve. That was just my best guess from the research I’ve done since the exhaust pipe was sucking air/paper back.
 

oconnef

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Update: got all the tools to accomplish the task, went ahead and pulled rocker arms and pushrods hoping for a bent push rod but all were straight….only thing of note was that they were completely caked in crud. If that’s the state of the innards, I’m guessing the stuck valve may be correct, if not worse. I’m not sure if I noticed the “bullseye pattern” on the affected cylinder so I’m hoping it’s stuck and this job will free it!

That said, the pattern is very very faint on all valve stems so I also admit I may be shooting in the dark here.
BFE9F749-230C-4D7E-A81A-9706CE4D7E3A.jpeg
 

oconnef

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Ha, me too. Might research TSB 09-003-03. There's a thread here about it somewhere but the search didn't show anything.
Probably going to end up posting this since there’s not a single dedicated thread to the TSB, but sure looks like the intake valve (bottom) has more of the bullseye pattern than the exhaust for cylinder 1.

Also I’ve seen some folks mentioned “the ruler test”… Looks like the exhaust valve spring is sitting higher than the intake. But, I may be stepping over my knowledge at this point.

B2CF446F-C582-46E3-A870-EB9DBFA2D35E.jpeg


C5CCE703-DA5D-42FC-9422-EFBF3AD0BEA6.jpeg
 

SkylinesSuck

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I haven't read back farther than the pic. They are supposed to be level if they are both on the base circle of the cam. Are you sure they are?
 

oconnef

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Oh, and duh. Clearly no rocker arms in that pic. I wish I posted that later in the day so I could blame it on 🍺

So… I’m going to follow thru with the service bulletin, but does this indicate a bad valve seat? Why would the spring present itself higher? If I understand it’s sitting higher that means the valve is not stuck open but closed father than it should be?

I’m sure the answer would present itself with pulling the head but that’s a farther job than I might be willing to get into at this point.