Mopar 4.7 info - dropped valve seats
Hello all, this is a public service announcement for anyone that is or is going to replace / rebuild heads or engine swap for the jeep 4.7 engine or 4.7 HO engine.
GET THE VALVE SEATS TACKED IN!!
I cannot emphasize that enough. The heads are aluminum and the seats are steel. They can fall out at random with or without the heads being overheated. I have done some research and found a few threads about this very problem and even the Mopar techs I have as friends know if this. I didn't know about this until it happened to me so I wanted to share this in case anyone else is in the same boat doesn't know yet or searched this site for help on the issue. The 4.7s come in these following vehicles in case you are looking for parts. Mine is a 2001 and I think they redesigned it a bit from 01 on up:
1999–2009 Jeep Grand Cherokee
2000–2011 Dodge Dakota
2000–2009 Dodge Durango
2002–present Dodge Ram 1500
2006–2009 Jeep Commander
2007–2009 Chrysler Aspen
4.7 HO applications:
2002–2004 Jeep Grand Cherokee
2002–2007 Dodge Dakota
2002–2007 Dodge Ram 1500
2006–2007 Mitsubishi Raider
Here is a thread of a guy who did a rebuild after his seat fell, and is screwed up both heads. He has a few threads on a few sites and this one looks to be most complete:
Luckily mine was just a tap on the piston and no carnage or bottom end dismantleing needed. I am having the machine shop tapping in all the seats. $75 per head.
Keep on jeeping!
I'm an ASE master tech and I have also seen this. The last one had a misfire caused by a cam follower out of place. It turned out to be a dropped valve seat. It was caught in time, it didn't trash the engine. Ron
'02 GC 4.7L Valve seat dropped
My '02 GC 4.7L limited dropped the valve seat when I cranked it up.
The engine was taken care of and at 110K miles I looked forward to 5 more good years with it. This happened in June of 2013.
Changed oil every 4 to 5K Miles.
Put $5,000 in repairs since I bought it in 2008.
This car was set for at least another 40K miles
I cranked it up one day and that was it.
The valve seat dropped and it blew a hole in the piston.
I was told this is a known problem with the 4.0 and the 4.7 liter engines for the 1999 to 2004 jeeps.
The Jeep dealer charge me $640 to tell me what was wrong.
Needless to say I feel let down by Jeep.
So I will no longer purchase a Jeep vehicle and will advise everyone I know about this issue.
That happens on many Aluminum heads, not just the aluminum heads in jeeps.
It happens in aftermarket aluminum heads also.
The other issue is when they are replaced they should have a .006 .007 press fit, not .003 to .005 like steel heads.
Many places make a mistake and use the .003 .005 seat and in a short time you have a problem.
however seats falling out can be from heat or detonation.
Staking is something i wouldn't do, that can and does lead to hot spots.
If the seats are installed with a .006 .007 fit and they are installed CORRECTLY, which means evenly in and no cocking they'll never fall out, if they cock a little they will cut the bore for the seat and you will not have that .006 press fit.
The 4.7, 3.7 and the ford 4.0 are famous for this. And yes it happens to all aluminum heads. One simple overheat And poof.
There is a jeep shop in town where I reside and I have about 8 WJs I can pick from for parts for the dropped seat issue. Its sad looking underneath it while scoring my part and seeing the holes in the bottom of the oil pan from the thrown rods from these engines dropping seats.
If you score and car with the 4.7 (or any aluminum head engine with pressed in valve seats) first thing is pull the heads off and have a machine shop tack in the valve seats, do a valve job, swap timing chain and tensions while you are in there, and then you should be good to go. But yea, 4.7s over 150K or used, its a guessing game when they will drop a seat. Mine fell due to a engine misfire, and perhaps an overheat from the previous owner and from there it was a timebomb.
Depends on what Machine shop you use and what you want done. For me I had another seat fall so either the workmanship at the machine shop I used (Quality Engine in Austin) sucks or parts they used weren't up to par. Either way here was the first go:
about $320 for the head work, new seats and tacking with valve job, clean and check to ensure the heads were re usable
$12 for the Engine coolant
$20 to $50 for Oil
$150 for the timing chain / gears / guides depending where you source. Remember you get what you pay for. A screw up here and you loose an engine
$50 for the head gaskets
$40 for the exhaust / timing chain cover gaskets.
$20 for the freon (I get mine at Big lots for $6 a can. I use 3 cans)
8 to 10 hours of wrench time. I got it down to 6. This includes pulling the heads, timing the engine and pulling the exhaust manifolds (which took me about 2 hrs due to the small space between the rails.). I did the work without pulling the engine.
If a garage does the work, take the above and add about $1000 if they charge $100 an hour. They book this at 10 hours.
I had to do this twice. On the second round I had them use over sized valve seats and had them replace all seats and needed a piston. that was about $600 plus the rest of the parts again listed above. Shes still running. I hate the 4.7 engine because of this and now stay away from it due to the poorly designed heads in the 4.7(the 3.7 is the V6 version). May have been fixed in 2008 revision or in the HO version. I may sell this guy and get a GC with the trusty 4.0.
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