Rough run - engine missing - JeepForum.com
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post #1 of 9 Old 08-03-2019, 03:07 PM Thread Starter
stracener
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Rough run - engine missing

4.7L 2004 with 190,000 on the motor. Started up and had really rough running, and engine died. Start up again, still rough.

Pulled plugs, all look good.

No codes on scanner.

Compression test ó zero compression on #2, all others ~ 170.

Pulled passenger valve cover - found #2 rocker arm in bottom. Iím guessing I have a stuck valve ???

Or is there anything else it could be (maybe something that doesnít mean new heads!)img_1941.jpg


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post #2 of 9 Old 08-05-2019, 08:47 AM
Double E
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Often this will occur because a hydraulic lifter will no longer compress due to sludge/debris build-up. When the rocker pops out, it can also take out the mount for that arm on the cylinder head. It looks like you got lucky in that respect.

If you can get it out, check that it is undamaged. Look for videos for how to pop it back in place. Then do an engine oil flush treatment in effort to clear the lifter from debris and sludge. Change oil a couple of times as well after a hundred miles or so between each fill.

With all of that RTV sitting on the valve cover gasket area, it is possible that some RTV chunks got in to the lifter and did this. You can see a chunk sitting on top of the other rocker arm as well. OEM-type gaskets do not require any RTV at replacement. Changing gaskets is a normal solution to resolve a gasket leak but you should not have needed that much RTV. I use a VERY light amount when replacing them, and even then only on the back half of the VC gasket...the lower part of the engine. Clean every piece of it out of the valvetrane first. You still might not get it all but that's your objective. The other side might have the same issue.

'04 Freedom Edition HO & '04 Overland HO (previous '00 Laredo 4.7)
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post #3 of 9 Old 08-10-2019, 07:08 PM Thread Starter
stracener
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Thanks Double. Yes I overdid it on the RTV, wonít do that again.

Iím into it now... pulling the head to see if the valve has dropped or if itís not the famous valve seat issue.

Going slow, but gonna get there. Got the fuel rail and intake manifold off. Head bolts out on passenger side, water pump off, ac compressor removed, and alternator off.

Hope to get the head off tomorrow, tough to get to the exhaust manifold bolts!!!

Will the head pull off easy enough or will I have to get out the BFH??




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post #4 of 9 Old 08-11-2019, 01:47 PM Thread Starter
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Head came off easy enough after I got the two bolts out that are by the timing chain.

Pulled it off and found this ó ouch!



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post #5 of 9 Old 08-11-2019, 05:00 PM
GmanWJ
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So is that what a dropped valve seat looks like?


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ok mostly just repairs, but we are closing in on a lift
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post #6 of 9 Old 08-12-2019, 08:22 AM
Double E
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Yes, but one who's owner has a lucky horseshoe. That valve seat let go yes...but did not get beyond the valve. It put a crescent in the piston top but that's not the end of the engine. Normally, when they go, the driver does not shut it down fast enough and the ring breaks apart, doing all kinds of damage to the cylinder wall, piston top, valve, etc.

The compression check and turning it over after the damage occurred did not do it any favors but it can be put back together with a new head. (Might as well do both heads, right?) Don;t sweat the crescent in the piston top. Smooth the mark out maybe but it will be fine. Swapping that one piston is not worth it.

Edit: Do I also see damage to the piston beside the one with the seat around the valve? That looks a little worse if so...

'04 Freedom Edition HO & '04 Overland HO (previous '00 Laredo 4.7)
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post #7 of 9 Old 10-22-2019, 06:13 PM Thread Starter
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Got these guys today, and will install this weekend. Waiting for gaskets and bolts, but they will make it Iím sure. Also changed oil pan gasket and want to do transmission while I have the Y-pipe out and have good access. Will be a packed weekend, you may see me on here looking for help!

Scared of doing the timing, everything else seems doable if I can work slowly and remember how things came apart. First time Iíve been in this deep!



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post #8 of 9 Old 11-17-2019, 05:31 PM Thread Starter
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New heads are in, and at 190,005 miles on the clock the Jeep runs better than ever. It was a big job with a lot of stuff getting changed out, but it seems good now with no leaks.

New heads, Cloyes timing set, FELPRO gaskets, MOPAR valve covers, water pump, exhaust manifold studs, oil pan gasket, transmission pan gasket, transmission filters and probably a few other things. Great experience and Iím glad to be driving the Jeep for winter!




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post #9 of 9 Old 11-18-2019, 10:44 AM
Double E
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Applause in order. Not many folks take that repair on themselves.
Should be good for another 200K miles.
Hose off the bottom side of that WJ and consider getting it coated so it does not rust apart and take away all of that effort.

'04 Freedom Edition HO & '04 Overland HO (previous '00 Laredo 4.7)
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