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Old 11-15-2012, 03:18 PM
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'04 Jeep Cherokee V8 - removing right cylinder head without taking timing chain off?

Hi guys,

First time here, thanks for reading my question.

I'd like to remove the right head. I believe I have a burnt valve, since I have no compression one cylinder and I've discovered a rocker arm fell off in that cylinder (after removing the cover), after I overheated the engine. Regardless, I have to have the head looked at.

I've read through the shop manual and have noticed that it instructs removal of the timing chain. I've also read (on this forum) that this is not necessary.

Can someone clarify this? I'd rather not remove the cover if I don't have to, and I don't have the idler sprocket tool.

If it's feasible (and not stupid) to do so, can someone walk me through the process?

My questions:

1. Do I have to remove the cam to remove the cam chain sprocket?
2. Without removing the timing chain cover and the tensioners and guides is there too much pressure on the chain to remove the sprocket bolt?
3. While I've got the engine apart should I also pull the left head and have it inspected/reconditioned?

The car has 125k miles on it.

I understand about TDC and the V8 marks etc, but hesitant to move forward without removing the timing chain cover unless someone knows if it's been done safely.

Thanks so much.

JW
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Old 11-15-2012, 06:12 PM
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Re: '04 Jeep Cherokee V8 - removing right cylinder head without taking timing chain o

The 4.7 in peticular doesn't like to be overheated. Warped heads will be the result. Also the valve guides can come loose and drop, which causes the rocker arm to fall of. So if you have a problem with the right head due to overheating, there is a good change that there are problems on the left head as well. You could do a cylinder leak check to see how the condition is and then decide what to do.
When you want to remove a head, you have to remove the chain first.
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Old 11-15-2012, 08:40 PM
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Re: '04 Jeep Cherokee V8 - removing right cylinder head without taking timing chain o

Well buddy! I had a '04 Ram 1500 with the same problem. First time I realized I had some trouble it left me stranded in the highway with a severe case of fallen rocker arms. I didn't had any troubles with my engine before (154,000 miles without any troubles), so I hook it up and bring it back home where I started dismantling to get it repaired. I took both heads off, sent them to the machine shop to have them checked for cracks, warping and get a whole valve job performed with new lifters. After having them back, I reassembled the whole thing with new timing chain, sprockets, and guides, fresh new Fel-pro gaskets, I even replaced all head bolts. What ever I took off and I guessed it was a replaceable item after all the mileage, I did. Anyway, when I was done, I took the truck for a spin around a few blocks with my wifey so to have an extra pair of ears to check on the run.
I took the truck the next morning to go to work (about 45min commute) and arrived well. When it was quitting time, I reached my truck to leave and guess what! When I started the engine, two rocker arms fell off again. But that didn't stopped me, I drove back home like that (doing only 35MPH but hey! it was a damaged engine) and started disassembling back just one head. I took off the timing chains and took off only the right head which was the one with the fallen rockers. For my surprise, one of the exhaust valves was bent. Again with the head to the machine shop. When I got it back, I've researched for the problem with another people but found nothing, but at last somebody gave me light in the way, and found out that a clogged screen on the oil pump pick-up at the oil pan was the reason why rockers were falling. Since the rocker lifters are hydraulic type, they need oil to keep the tension between the cam lobe and the valve tip otherwise the lifters "collapse" meaning not to have enough oil to keep the rockers from falling. You have two options; have the oil pan out and take off the oil pick up tube to clean or replace the oil screen or do what I did (without the mess of disassembling the whole engine), I just went with the guys from AIRRAM.COM and bought a set of solid lifters for the 4.7lt. Men, that was the best upgrade to do to this engine. One- it works! Second- it gives the engine a more taut throttle response and a worry-less high revving performance. I recommend this upgrade to anyone with a 4.7 engine even if it hasn't went through the "fallen rocker blues" yet.
So... if you want to get rid of that problem once for all, do not hesitate to give the AIRRAM.COM guys a try. You'll never regret it! Take my word for it.
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Old 11-15-2012, 08:53 PM
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Re: '04 Jeep Cherokee V8 - removing right cylinder head without taking timing chain o

Sorry man! I got carried away and didn't answer your questions.
First answer; You do no have to remove the cam to remove the cam chain sprocket, it will come off easily unscrewing the sprocket bolt and giving it a little tap to loose it off.
Second answer; there is a slight manageable tension on the chain against the sprocket but couldn't be a reason no to have it removed.
Third answer; If you're removing one head, it's cool, you can do just one head. But if you want to freshen up your engine upper, get both off. I recommend to have both done.

Hope this help you with your project.
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Old 11-15-2012, 09:35 PM
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Re: '04 Jeep Cherokee V8 - removing right cylinder head without taking timing chain o

Frango,

Thanks for the reply. I'm hoping there isn't too much damage. I can't afford a new car right now.

If the heads are warped, must they be replaced? Also when the guide falls does that cause damage to the cylinders, etc? I didn't hear any noise. Can that be reconditioned by a machine shop?

Hoguie,

Thanks man, as well.

That's an interesting situation you speak of. I hope that isn't the case with this engine. Solid lifters is an interesting choice.

I should probably have both heads reconditioned, you're right.

My other question, is it worth the expense? Heads checked for warp and cracks, reconditioned, valve guides replaced, etc. Plus any other damage that may be there.

There's an oil leak somewhere, as well.

Hmmm.

I know those questions only have guesses as answers, but thanks.

Jim
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Old 11-15-2012, 09:42 PM
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Re: '04 Jeep Cherokee V8 - removing right cylinder head without taking timing chain o

If the heads are warped and not cracked, they can be resurfaced by a machine shop. There is a fair amount of time involved in checking out heads but it is worth it. You do not want to put it back together with a warped head. I would also look into options for complete remanufactured heads to swap in place of the current heads and turn the old head/heads in as cores. If it were mine, I would replace both heads while I had it that far apart. The labor to pull the second head once the intake and timing chain are off are minimal. If it was hot enough to damage one side then the other side is likely damaged.

Rockauto.com has reman heads for just shy of $500/side before core. You will need your vin handy to get the correct one.
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Old 11-16-2012, 06:30 AM
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Re: '04 Jeep Cherokee V8 - removing right cylinder head without taking timing chain o

The jeep manual says that loose valve guides are not repairable and the head should be changed, but machine shops can put new valve guides in. As far as i know there will not be any internal damage due to dropped guides. When a guide drops, it creates a too large play and the rocker arm can simply fall of. The tip from Hoguie7 could also be a reason, however due to the fact that your problem started after an overheat, i would expect more a dropped guide.
Then regarding removing the head, when you would remove the head, you should at least block the chain tensioner. Failing to do so, will cause the tensioner to extend and it will not return by itself, so you will have to open it anyway.
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