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What year was your dropped valve 4.7?

  • 1999

    Votes: 9 11.5%
  • 2000

    Votes: 12 15.4%
  • 2001

    Votes: 10 12.8%
  • 2002

    Votes: 21 26.9%
  • 2003

    Votes: 3 3.8%
  • 2004

    Votes: 24 30.8%
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155,000 on the bottom end. Runs perfect besides the head issues, cylinders still have a nice cross hatch visible.
 

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No issues so far on my 2004 HO Grand Cherokee Limited which I bought pre-owned at 84,000 miles. Thanks for great series of posts on this thread regarding valve seat drop, all informative but disturbing. I will look at ANY misfire issue, a potential valve seat or lifter issue.

I had thought my 2004 (Manufacture date is Jan 2003 go figure) had the valve seats updated in the release of the 2004 model year/series, but I guess that is not the case. Previously, I had a 2002 WJ with the 4.0, (no issues ever) that lasted 150,000 miles before some idiot ran into it and totaled it in a parking lot!

Regarding overheating, as a potential cause, my HO may have overheated at 100,000 miles. I was entering a car wash and the attendant while spraying prewash water at the HO said I had water dripping from the front. Checked temp gage and temp was reading normal - so all OK, I thought! Drove home, a couple of miles, found that water was spilling out the front of the water pump weep hole, a lot of water. The temperature gage still read in the NORMAL range, but the cooling fan on the radiator was running (roaring) in high gear! Turned off engine immediately. So TIP to the WISE, once air enters the WJ 4.7 cooling system, the temperature gage cannot be trusted as a means to indicate overheating! The temp sensor is a water sensor, not an air sensor so once air enters the WJ cooling system and pressure drops for any reason, hose leaks, bad pumps, you are in trouble. Morale of story, visual inspection for water leaks if you hear that cooling fan running on high! Just keep and eye out for any type of water leak as a normal course of WJ life.

Normally, on my 2004 4.7 HO, even in Phoenix, it takes a really hot day to engage that cooling fan. I replaced water pump with NEW Mopar and not a rebuilt unit. My water pump was factory original to Jeep. As of 120,000 miles now of mostly highway mileage no issues with valve seats so far. But I will watch it like a hawk now for misfires, thanks! Maybe I should go head shopping just in case.

Also, I recommend replacing the upper and lower radiator hoses and the heater hoses with HPS Performance Silicone hoses. The WJ - 4.7L series is prone to overheating, as small leaks around the hose ends can cause problems with the cooling system, ie air bubble in the top radiator hose just before the water bleed fitting. The silicone hoses don't shrink, HPS provides a high quality hose clamp and not the hose ending crap sold in most automotive stores.

Regarding oil, I use Valvoline High Mileage Synthetic 10-30w. Other threads had mentioned to avoid potential issues in 4.7's as the self adjusting lifters could stick and result in the lifter falling out and subsequent valve damage. Engine sludge build-up caused by the use of cheap standard engine oil and lack of regular engine oil change is usually listed as a cause for the lifters sticking. So, I ran an engine flush every six months with synthetic oil and filter changes every 90 days for my first year of ownership of the HO to get rid of sludge or other buildup. I think the synthetic oil is critical to avoid the sticking lifter issue, besides other advantages.

So, regarding the poll, I think maybe widening the response to the thread to include other types of valve damage due to overheating. Not everyone is willing to diagnose just valve seats. It all just gets dismissed as "off to junkyard" due to potential engine damage and not categorized according to valve seats or stuck lifters or broken valves.

My wife worked at the admin office for national auto repair firm. I asked her to poll some of the shop mechanic's informally. According to them the WJ series had lots of cooling issues with the 4.7's resulting in engine damage of one type or another that owners on high mileage WJ's (around 90-100K ) just did not want to spend $$$ to repair.
 

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Tell me about this " valve seats updated in the release of the 2004 model year/series". Never heard that before. Updated how? Source for that info? I never heard that Chrysler ever changed the head design on the 4.7 or admitted to it having any problems.
 

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Glad to hear your HO is running good. The PCV system on these is junk as well, you would not have the problem we have up here of condensation freezing in the valve itself. I believe this is a major issue with the sludge problem with major milkshake on the back of the oil fill cap due to insufficient air flow within the engine. I remedied the problem copying how they did it in I believe 06 and up. The PCV valve on the fill neck is no longer used being replaced by a large one (3/4" nipple) that screws into the rear of the drivers head in place of the stock nipple that was there. Now the PCV valve runs to a catch can that is connected to the intake vacuum source with 3/4" ID reinforced vacuum hose on the drivers side and the nipple on the passenger side head is now the intake source for the PCV system with a hose running to the resonator box. This is my write up on it. https://www.jeepforum.com/forum/f310/pcv-system-mod-4-7-a-4332243/
You living in Phoenix can benefit from getting the hot air from under the hood as well. I lived in The Valley for most of the 80's, stationed at Luke AFB. Our unibodies eliminate the body/frame gap in the engine bay creating a large air trap. Stuff a V8 in there and all the goods to run it and all of a sudden there is nowhere for hot air that has passed through the radiator to go as well as the air already in there heated by the radiance of the engine heat. That now prevents the air from entering the radiator to begin with, venting the hood will greatly reduce your engine compartment temps and allow the air from outside the radiator to more easily pass through it allowing it to be more effective as well. Helps the AC as well. If you don't want to put a hole in your hood like me the back of the hood can be raised with a few washers on the hinges and remove the weatherstrip sealing the cowl to the hood. This allows a surprising amount of very hot air to escape in summer. Here in Michigan we have nowhere near the heat you guys do however the heat of the air coming from this gap in summer is too hot to stand with my hand.
 

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This allows a surprising amount of very hot air to escape in summer. Here in Michigan we have nowhere near the heat you guys do however the heat of the air coming from this gap in summer is too hot to stand with my hand.
i'd be wondering about it heating up the windshield (transferring heat into the cabin) and allowing superheated air into the cowl (again, transferring heat into the cabin) i'd be looking at a way to force the air out the bottom, to get sucked out back. it kinda goes that way anyways, but there has to be a better way to remove heat. :frown2:
 

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I have been doing this since the 80's when I lived in Arizona, it was a common thing there among the car guys as well. We used to go as far as using AC condensers as trans coolers mounted in the back of the truck bed... I have never had an issue with excessive heat at the cowl, the heat dissipates pretty quick once out from under the confines of the hood.
 

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WJ 4.7 HO my 2002
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Cooling of the engine bay is an interesting point of discussion.
On one other thread, with @Double E We were discussing about air deflectors at sides of the radiator that force air throught radiator instead directly in the engine bay allowing cooling of the engine.
On 2004 models, air deflectors has been deleted from factory; I wonder if this could be a useful modify for the previous mys...
2004s AC condenser and power steering oil coolers are different from previous mys, this thing probably should be considered.
A friend of mine with a 00 (be strangely has hydro fan) has no radiator deflectors, and his engine temp stays always lower than WJs equipped with them...: could it be a random case?
 

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mak_v8 and I were discussing those deflectors and I since learned that they had been deleted, so you wont find them on the '04 models.
 

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I’d expect you’d know if you had any problems with a JY motor in 30 days, maybe less. I used a JY motor in my ES300 with similar warrantee and it’s been 6 yrs now and another 120k miles on her. Wish you the best!
 

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2002 Jeep WJ Grand Cherokee
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19:30 25 October 2021 @ ~217k miles: halfway through a 500 mile road trip, merging onto US highway 101 just south of downtown San Francisco, California. #1 intake valve seat dropped, valve stuck open, and the cam kicked out the rocker arm. I expected this event to be a lot more noisy and dramatic than it was, but no audible clattering to be heard, just quietly slipped the rocker arm off to the side, resulting in a significant loss in power.

Flashing CEL, 2+ cylinders misfiring, locked out the O/D and drove another 250 miles home. Actually had to stop once to refuel ... it immediately stalled when I left the highway but was able to restart and coax her to get me home.

Dropped seat diagnosis confirmed by my local shop, which will be doing an engine swap for me. I snapped the attached pic when I removed the valve cover to inspect and found the rocker arm had been spit out.

Never been overheated, always use Mobil 1 synthetic.

 

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Sorry for your loss. But envious of the thought of getting a fresh mill in a WJ.....
 

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Luckily it didn't trash the head, cores for these are pretty pricey it seems.
 

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I'm a happy 03 owner and it is somewhat relieving to see that my year seem to have the least valve seats dropped. Finger crossed it won't happen to me, I expect getting a new head for this engine in Sweden would be a costly matter.
 

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Dropped seat diagnosis confirmed by my local shop, which will be doing an engine swap for me.
Who did you wind up getting the engine from? Was it pricey?

I'm a happy 03 owner and it is somewhat relieving to see that my year seem to have the least valve seats dropped. Finger crossed it won't happen to me, I expect getting a new head for this engine in Sweden would be a costly matter.
My machinist said all the 4.7s were like this. The tolerance isn't tight enough between the seat and the head. If you replace the seats proactively, you can avoid it.
 

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2002 Jeep WJ Grand Cherokee
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Who did you wind up getting the engine from? Was it pricey?
Lol ... Yes, it was pricey. I did not have time to deal with this on my own so I had a local shop do it. They swapped in a Jasper which was somewhere in the neighborhood of just under $5k for the long block and the install kit. Add $2.4k install and a few other items I wanted in there ... I think you get the idea. Guess I like my Jeep.
 

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Well, add me to the list, my 04 dropped an intake valve seat a few days ago and I just pulled the head today. I used to race quite a bit (G2 Hemis) and have seen plenty of carnage, but it's still impressive how badly things can go in just a couple of seconds...at idle! Chamber might be salvageable and the piston needs to be replaced. The plan is to find a suitable donor engine to swap in while I do a proper rebuild of my existing engine. I don't trust anyone else's work, so I'll just build it the way I like.
Automotive tire Road surface Manhole cover Hubcap Wheel
Automotive tire Tire Motor vehicle Rim Alloy wheel
 

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Sorry to hear it mate!

On the subject on dropped valve seats and rebuilding engines, is there any preventive action that can be taken when rebuilding to actually stop it from happening again?
 
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