4.7 Dropped Valve Seat - YEAR POLL - Page 4 - JeepForum.com
View Poll Results: What year was your dropped valve 4.7?
1999 8 11.59%
2000 10 14.49%
2001 8 11.59%
2002 19 27.54%
2003 3 4.35%
2004 22 31.88%
Multiple Choice Poll. Voters: 69. You may not vote on this poll

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post #46 of 171 Old 12-20-2016, 08:35 AM
BuickNut
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Quote:
Originally Posted by HarryH3 View Post
I've read that excessive ping/detonation can contribute to the problem as well. It makes the combustion chamber temps go way above normal. The aluminum head expands more than the steel valve seat as it heats up.
With that being said, I wonder how many H.O.s compared to standard 4.7s? Since standard 4.7 has no knock sensors compared to the H.O.s 2 sensors in the intake valley.

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post #47 of 171 Old 12-20-2016, 08:57 AM
HarryH3
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Quote:
Originally Posted by BuickNut View Post
With that being said, I wonder how many H.O.s compared to standard 4.7s? Since standard 4.7 has no knock sensors compared to the H.O.s 2 sensors in the intake valley.
Theoretically, the non-HO should be less prone to detonation since it has a lower compression ratio. The reality is that modern gasoline sucks, so it may or may not really meet the octane rating on the pump. One still has to wonder why Jeep cheaped out and left the knock sensors off of them.
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post #48 of 171 Old 12-25-2016, 06:01 PM
Krwlnrx
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How to you determine a dropped valve seat? Any test I can run?

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post #49 of 171 Old 12-26-2016, 03:41 AM
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Low compressions (not at first though), misfire (again not at first), one valve sitting lower than the others (when closed of course) when you take the valve covers off....pop the lifters off to view all at once.....and finally a horrendous misfire and rattle as the bits off seat embed themselves in your piston and head and bend the valves and perhaps escape into the inlet or exhaust manifold. That just about covers it!!!
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post #50 of 171 Old 01-25-2017, 11:33 AM
gvelis
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2002 still going strong 287k miles!
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post #51 of 171 Old 02-03-2017, 04:08 PM
sartech
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1999

1999
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post #52 of 171 Old 04-09-2017, 07:11 PM
99WJBuild
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So since I'm going to be dropping in a 4.7 to replace the blown one in my build, is there anything I can do on the front end to remedy this that would be easier with the motor on the stand? Any other items I should consider changing out with that in mind as well?
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post #53 of 171 Old 04-09-2017, 08:34 PM
HarryH3
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Originally Posted by 99WJBuild View Post
So since I'm going to be dropping in a 4.7 to replace the blown one in my build, is there anything I can do on the front end to remedy this that would be easier with the motor on the stand? Any other items I should consider changing out with that in mind as well?
It would require pulling the heads. Best fix would be to take them to a machine shop and have new valve seats installed (word is that Chrysler didn't make the interference fit quite tight enough between the seats and heads on the 4.7) and also have them staked in place to make sure that they can't fall out.

I'd be somewhat concerned about just staking the factory seats, since it could deform them ever so slightly and screw up the sealing between the seat and valve face.
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post #54 of 171 Old 04-09-2017, 10:04 PM
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It's cheaper to just install new heads. By the time a machine shop does all the labour and parts you're into those old heads for more than you'd pay for new ones with oversized seats already installed. There is an eBay seller that sells rebuilt heads for under $600.
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post #55 of 171 Old 04-09-2017, 11:30 PM
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Mine is a 02, and the PO replaced the engine at 151k due to a dropped seat. There is currently only 20k on the reman engine. She runs strong and quiet. But this factory flaw makes me nervous and is my worst nightmare with my WJ. I've already invested a lot of money to this point and still have a good distance to go before my build is done. Would be devasting to get it close to its completion just to drop another seat along the way! So I do plan on replacing my heads once the build is near it's "end" (Jeeps are never done)
There are companies that are selling heads for the 4.7 that fixes some of the issues, such as pinning the valve seats.
Spending $600-800 for improved heads and weekend of my time is worth saving my Jeep and the headaches that would ensue if the valve seat(s) drop ruining my engine and costing $3500 to repair.

I find it even more unsettling that the 2002 model is running away with this poll!!!

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post #56 of 171 Old 04-10-2017, 07:09 PM
99WJBuild
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Thanks for the feedback. Much rather spend the time and money while on the stand than have it blow up in the Jeep. I will check some local machine shops just for good measure and go from there.
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post #57 of 171 Old 04-10-2017, 07:34 PM
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Some other noteworthy things to consider with the new heads.
Pinning the seats
Replacing the tensioners (check rocker arms)
And notably, there's a mod for the oil drain opening to be bigger

One company to check out is Odessa, there is another one but the name just isn't coming to me right now

It's not the Destination so much as the Journey!! - Cpt. Jack Sparrow

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post #58 of 171 Old 04-16-2017, 11:50 AM
Dag93
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I haven't had a dropped valve (knock on wood) but I have had PCM issues so I would like to poll on that. 2000 4.7

If it can't be fixed with Duct tape, it can't be fixed
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post #59 of 171 Old 04-17-2017, 09:19 AM
sartech
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I dont understand why it says I may not vote on this poll. I dropped a seat on a 1999 WJ. long story short, lots of money and better than new
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post #60 of 171 Old 04-17-2017, 01:26 PM
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Quote:
Originally Posted by sartech View Post
I dont understand why it says I may not vote on this poll. I dropped a seat on a 1999 WJ. long story short, lots of money and better than new
i think you need more posts before you can vote.
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