'02 WJ 4.7 HO questions. - JeepForum.com
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post #1 of 14 Old 09-20-2021, 11:15 AM Thread Starter
tazdevl35
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'02 WJ 4.7 HO questions.

I picked up an '02 JGC Limited with a 4.7 vin N that #7 intake valve had very slightly kissed the piston. Totally repairable by rebuilding the heads installing seats or using replacement heads. It has 274K miles on it ATM. Now, I also picked up a perfectly maintained well running 02 Vin J 4.7, (HO) with well under 100K miles on it, for very cheap, less than the cost of doing the heads on my current motor either way. Both engines are 16 tooth J-Tec 3 plug PCM. I am aware that I'll have to run premium fuel if I do the swap, since the J-Tec non-HO harness had no provisions for the knock sensor connectors which the HO uses, which my current non-HO doesn't have. Thus there could be detonation using lesser octane fuel..

Does anyone have any experiences to share with doing this swap? Looks like a cheap way to pick up a decent motor with a decent bump in HP/Torque that will pretty much plug and play otherwise. Any insights into possible necessary mods to make it work will be helpful. Also, should the PCM be reprogrammed or a custom tune installed for the HO motor?

Does anyone have information regarding the 4.7 HO versus non-HO dropping valves? I've heard/read that if you keep the HO motor's cooling systems in good shape and running cool, that they are less prone to drop valve seats? Any truth to this? I've only ever seen non-ho 4.7's with the dropped seats, but I've read a few HO 4.7's dropped them as well.

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post #2 of 14 Old 09-20-2021, 12:57 PM
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There's nothing keeping the HO's valve seats in more so than the non-HO.
Keep them both cool or else is the prevailing opinion but the actual reason is as yet not fully understood as being consistent across all that have dropped them.

I'm guessing the frequency we hear of may be less for the HO just because there are not as many as the non-HO.
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post #3 of 14 Old 09-20-2021, 01:21 PM
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You need to change out the intake valve seats on the new HO motor as well.

All of them. Not just the one that dropped.

They all will fail eventually as the tolerances weren't tight enough at the factory. If you redo the intake valve seats they won't fail a second time if the machine shop is competent.

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post #4 of 14 Old 09-20-2021, 06:48 PM Thread Starter
tazdevl35
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Wj tazdevl35

Quote:
Originally Posted by CraigMBAx View Post
You need to change out the intake valve seats on the new HO motor as well.

All of them. Not just the one that dropped.

They all will fail eventually as the tolerances weren't tight enough at the factory. If you redo the intake valve seats they won't fail a second time if the machine shop is competent.
The low mileage HO 4.7 doesn't have any dropped valves, only the original 4.7 non-HO in the GC at the moment. I was going to do the heads on that motor as it was caught in time before it did any damage, other than a small 1/16" deep crescent shape from the valve hanging slightly open. No shrapnel, no busted piston, valve or combustion chamber.

I WAS going to rebuild that motor and have all the valve seats done until I happened across the low mileage 4.7 HO that runs perfect and has zero issues. It came out of a '02 JGC Limited that was hit in the a$$ hard, but otherwise runs fine. Since I got the Jeep with the dropped #7 intake valve cheap, (400$), and the low mile HO motor just as cheap, I figured I'd drop this HO in place of the motor with the dropped valve, then build the non-HO motor up at my leisure. Perhaps 'll put some Air Ram goodies in it, and a blower while I'm rebuilding it.

So to make it clear the engine I bought (also a '02..a 4.7 HO Vin J from a GCL) has ZERO issues whatsoever, it even had the proper HOAT coolant in it and no sludge buildup internally. So it's good. My question is has anyone else done the swap and besides not being able to run knock sensors, requiring premium fuel to prevent detonation, is there anything else I need to be aware of when doing the swap?

For those who have done the swap from non-HO to HO, is there a perceptible difference in seat of the pants driving? The GC it's going in has a 545RFE and 3.73 gears as well as Quadratrack and a Sure Grip in the rear. Not sure about the front diff, I'm thinking of putting a Vari-Loc in it before its all said and done. I need to run the vin and see exactly how it was built and with what options

I'm thinking it'll be a nice inexpensive ride when it's all said and done. Body and interior are quite nice for the age and the price was right.. The only reason it's not being worked on this very second is because I'm putting a motor in the wife's '99 that cracked #6 piston up to the oil ring land. Typical. But the wife comes first.

With any luck, I'll have the motor in my '02 before winter and snow hit us here in Pa.! Should be a fun toy to to go out and blast around in the snow..
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post #5 of 14 Old 09-21-2021, 06:12 AM
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And get them peened in place while at it. Any aluminum head can drop a seat, most don't though. I have seen Hemi's do it, 3.7's do it and even the mighty Viper V10 has done it. Have pulled a few heads of Jags in the old days with a dropped seat as well. On the other side, I have never heard of a 4.6 Ford doing it, even ones that have 5 digit idle hours and been overheated many times...

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post #6 of 14 Old 09-21-2021, 06:16 AM
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As far as seat of the pants between the 2 you will notice a difference, it is the cams that make most of that difference. The air intake system is also different as you can tell between the two. It is why HO cams in a standard 4.7 are so popular a swap.

2004 Limited, 4.7 modded slightly, IRO 3" RockLink LA front, adjustable SA rear, Bilsteins, Addco bar, JKS disconnects. Coming attractions include 242hd, IRO SYE and Woods DS right after the new engine/trans..
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post #7 of 14 Old 10-01-2021, 12:53 PM
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236k miles on this 2002 WJ 4.7HO and so far so good. Synthetic oil, always up on coolant and upgraded to a Chinese (meh) all welded aluminum radiator a year or more ago and it’s holding up ok here. Now that I’ve said that I’ll drop one on my way home from work….. ��

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post #8 of 14 Old 10-01-2021, 01:06 PM
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Quote:
Originally Posted by tazdevl35 View Post
The low mileage HO 4.7 doesn't have any dropped valves, only the original 4.7 non-HO in the GC at the moment.
Yet.

Every 4.7 needs to have it's timing chain guides replaced every 100K, and if it's never had them done, the intake seats removed and replaced. They are all ticking time bombs waiting to fail. It's not if it's how soon.

I don't think the pinning is necessary if the machine shop is competent and gets the tolerances right when they replace them.

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post #9 of 14 Old 10-01-2021, 01:58 PM
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I agree peening may not be mandatory however it is the only way to pretty much eliminate seats falling out. I look at it like safety wire on fasteners, may not be needed but nice to know the bolts will NOT come off.

2004 Limited, 4.7 modded slightly, IRO 3" RockLink LA front, adjustable SA rear, Bilsteins, Addco bar, JKS disconnects. Coming attractions include 242hd, IRO SYE and Woods DS right after the new engine/trans..
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post #10 of 14 Old 10-01-2021, 05:50 PM
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Quote:
Originally Posted by cDee63 View Post
I agree peening may not be mandatory however it is the only way to pretty much eliminate seats falling out. I look at it like safety wire on fasteners, may not be needed but nice to know the bolts will NOT come off.
IMO it's not necessary.

We used to put trucks on propane on the farm, and we had to use these seats in the 70's (the factory ones were too soft and wouldn't last 15,000 miles). The advantage is the engine would run until the rods fell out of it (no more valve jobs) - sometimes 150,000 miles which was unheard of back then.

The downside is when they are installed incorrectly you get that debacle that is Ford Escort heads from the 80s on, and 4.7 and 3.7 heads.

If the replacement seats are put in by a competent machinist, it won't ever be a problem. Hell, if Dahmer had done it right from the start it wouldn't have been a problem. But they didn't.

My machinist tells me he sees these failures all the time and the engine isn't terminal, but the client won't pony up the $$$ to do the job right. When mine sucked a head gasket, I took that as an opportunity to have them done.

It cost me $1200 but I know the job is right. Most other guys would go looking for the cheaper route and most reman heads they just fix that one seat that fell out, resurface them, and ship it.

Every. Single. 4.7. and. 3.7.

Will eventually drop an intake valve if you don't do something about it.

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post #11 of 14 Old 10-02-2021, 05:11 AM
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Quote:
Originally Posted by CraigMBAx View Post
Ö..Most other guys would go looking for the cheaper route and most reman heads they just fix that one seat that fell out, resurface them, and ship it.

Every. Single. 4.7. and. 3.7.

Will eventually drop an intake valve if you don't do something about it.
Thatís SHOCKING but I am sure you are right! WOW.

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post #12 of 14 Old 10-02-2021, 10:04 AM
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It is much the material as the installation process. The root cause is the use of sintered metal instead of conventional steel, the sintered ones cannot have as tight an interference fit. Typically it is .005" for cast iron and .007" for aluminum head material. I agree if done correctly peening is not necessary however not knowing whether or not the machine shop is competent until the seat falls out again is a risk I would rather not take. Like a seat belt, even knowing I most likely will not get in a wreck I wear it always just in case the other drivers around me are not competent. Peening to me is very cheap insurance.

2004 Limited, 4.7 modded slightly, IRO 3" RockLink LA front, adjustable SA rear, Bilsteins, Addco bar, JKS disconnects. Coming attractions include 242hd, IRO SYE and Woods DS right after the new engine/trans..
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post #13 of 14 Old 10-05-2021, 06:29 AM
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Good to know. Thanks CD.

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post #14 of 14 Old 10-05-2021, 10:14 AM
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Quote:
Originally Posted by cDee63 View Post
It is much the material as the installation process. The root cause is the use of sintered metal instead of conventional steel
We have been using those sintered metal valve seats in propane engines since the 70's without issue - abet they were in cast iron heads. The problem is installing them with the proper tolerances, which didn't happen by Mopar, into aluminum heads.

I actually don't care if they pin them or not as long as they are changed and you don't get the motor hot again.
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