jeep 4.7 woes

[69wannabe]

I bought a 2000 jeep grand cherokee a few years back with a blown up 4.7 V8 in it. Pulled the engine and rebuild the dead 4.7 and got the jeep up and running and really liked it. It ran great and was very peppy but about two weeks back I noticed it puffing some blue smoke at idle and then later when I took off up the road it rolled the blue smoke out the back something terrible. Haven't drove it until today and it started skipping on the way home. Got it home and started unplugging the coils one at a time to try and find the skip and the passenger side seems to be all good but a few on the driver side don't do anything when I unplugged them. Must have some kind of issue on the driver side head and I only have put 13,000 miles on it since I rebuilt it. The check engine light never came on so it's not an electrical issue I don't think especially with it smoking like it was doing the other day.

I have an 04 grand cherokee with the 4.0 I was planning to sell but since the 4,7 has decided to fail all of a sudden i'm going to see what I can get out of the 2000 V8 jeep and keep the 04 model. Kind of glad it decided to mess up before I sold the 04 so I will still have a good jeep to drive. I have always been told to avoid the 4.7 V8's but I have seen several with 200,000+ miles on them and still running good but this is not one of them. No more over head cam V8 engines for me!!!!!

[alfaitalia]

Almost certainly dropped valve seats....they all do it sooner or later. I'm also over on the Jeep forum...there are laterally hundreds of posts on the very same subject. They are just pushed into the head...so after many heat cycles they slowly start to move down. First off you lose compression and get misfires..then it falls out completely and takes the valves and piston with it...damaging the combustion chamber at the same time. Many builders offer modded heads with pinned seats to try and avoid this. Cam location would make no difference...it's just the poor quality of the WJ shining through...lol. Don't think the straight six in your  4.slo will be any better...they like to lose piston shirts pretty regularly...listen out for sudden and excessive piston slap ...and then stop driving it immediately or the piston will tilt, and destroy did and bore. More often or not is the back two piston that go. Stronger piston are available after market.

[69wannabe]

I know about the 4.0 pistons and the skirts breaking off, at least I can rebuild a 4.0 and get many miles out of it without worrying about it coming back apart at only 13,000 miles after a rebuild.

[LaOtto70Charger]

Is the Jeep 4.7 any different than the Dodge 4.7?  Only asking because in October I sold my 2003 Dakota with the 4.7 V8 and 185,000 miles.  Never had any major issues with it, and I bought it brand new.  It would do some missing at idle only.  Never enough to be of concern.  Also did since like 20,000 miles.  Never used oil either.  Only traded because the body was rotting out, and the AC compressor was going. 

[69wannabe]

Yep, basically the same engine i'm pretty sure. Like I said I have seen some with over 200,000 miles on them but this one hasn't hit 150,000 yet and has been running fine until it started puffing smoke about 2 or 3 weeks ago. I am trying to sell it but nobody wants anything to do with a 4.7. If I still have it this winter and I get really bored I may pull it back apart and see what went wrong...

[ACUDANUT]

Almost certainly dropped valve seats....they all do it sooner or later. I'm also over on the Jeep forum...there are laterally hundreds of posts on the very same subject. They are just pushed into the head...so after many heat cycles they slowly start to move down. First off you lose compression and get misfires..then it falls out completely and takes the valves and piston with it...damaging the combustion chamber at the same time. Many builders offer modded heads with pinned seats to try and avoid this. Cam location would make no difference...it's just the poor quality of the WJ shining through...lol. Don't think the straight six in your  4.slo will be any better...they like to lose piston shirts pretty regularly...listen out for sudden and excessive piston slap ...and then stop driving it immediately or the piston will tilt, and destroy did and bore. More often or not is the back two piston that go. Stronger piston are available after market.

Just curious, do all people from the UK follow our U.S. cars this much ?

[alfaitalia]

No....very few in fact....just us mad folks who like US classic cars (like some UK classics too!) and those of us who want a 4X4 that's a bit different from all the Japanese stuff and LandRovers you see everywhere over here. I miss my old 2004 WJ Grand Cherokee. I have well over 6000 post over on the US based Jeep Forum. Not many on the forum ran diesels though as there were never of the Austrian built Jeeps imported to the US.

[69wannabe]

I agree and you are most likely accurate about it having a head issue, it has never ran hot since I got it running in 2015 and the oil pressure is still showing good. I had one head rebuilt by my local machine shop and one had to be replaced so I wound up with a reman on one side but I don't remember which side was which but the driver side is the side with the issue. I am almost sure that is the side that was the reman head. I have an 04 WJ with the 4.0 and it's a really nice little jeep, runs great and has 190,000 miles on it. I had to pull the oil pan recently and do an oil pan gasket so I went ahead and did a new oil pump and pick up tube and a new rear main seal too. I have owned it since 2013 and always changed the oil every 3000 miles and that oil pan was cleaner than the floor in my house!! LOL It was very clean and didn't have no sludge or even build up on the sides of the oil pan, I basically sprayed it good with brake cleaner and wiped it out good and that was it. I have rebuilt several 4.0's and had no engine or head failures that I know of and I have one I rebuilt for my daughters 2000 WJ that had 195,000 when I bought it with a bad engine, built the engine and now it has 248,000 miles on it and it's still running good (knock on wood) I will most likely wind up pulling the 4.7 jeep back apart but I got several things going on and other jeeps I can drive so it may be toward the end of this year or next year before I get back to it.

[69wannabe]

Well it's been awhile and alot has changed from losing my job to starting a new job but I finally got back to the 4.7 jeep that decided to crap out on me all of a sudden. Done a compression test and the driver side was the problem, the passenger side cylinders were all between 145 and 150 on compression and the driver side only had one healthy cylinder and the other three were 120 and lower. the back cylinder was below 90. Pulled the front cover and the intake and pulled the head and dropped it at my local machine shop. Got a call about a week later and the head was basically junk. The valve guides were worn out and two of the seats had began to drop out. Got a new head for free since that was the reman head that had went bad. Got it swapped out and back together and so far it's back to normal and no skipping or smoking anymore. It wasn't as bad as I remember to work on but still it's a different kind of animal for sure.

[alfaitalia]

Hopefully your new head is the latest version....with the valve seats pinned/staked into position....otherwise a few overheats (easily done on these if you take her off road much) will be all it takes to be back at square one.

[krops cars]

I have learnt the hard way before.

[69wannabe]

Hopefully it will be good this time around, the entire cooling system was replaced when I did the rebuild on the engine back in 2015 and it never ran over 210 degrees even in hot summer weather. Think it must have been a monday or friday head LOL. I went ahead and put another new water pump on it since I had the front of the engine off and even in the 100 degree heat it's running about 200 to 205 and it's just a 2wd so no mud holes or rock crawling for me. Just like the pep of the V8 and hope it does good for normal everyday driving.....

[Kern Dog]

Almost certainly dropped valve seats....they all do it sooner or later.

That is a pessimistic view. You should have written that a LOT do, maybe that MANY do, not "They all do sooner or later".

[alfaitalia]

Maybe a little....but it does happen a lot due to poor manufacturer...at any mileage if they overheat a few times and commonly around 100 to 120,000 mile if they don't. Lots end up in the junk yard because of it.....if you don't do your own work the cost of the repairs is higher than the value of the Jeep.....don't forget they stopped making the WJ shape in 2004 (2005 in Europe) so even they newest ones are worth half of nothing. Go over to the Jeep section and there are loads of thread on it...and the 4.0 breaking piston skirts.
....but we still love them as they are the last "proper" Grand Cherokee...with solid axles front and rear that can easily be lifted for serious off road use....before they went to the IFS.

[Kern Dog]

I had a 2002 Ram 1500 with a 4.7. It ran fine and never gave any trouble. I sold it with 163,000 miles when I bought a 2006 Ram 1500 4wd.
I never overheated it...I don't know how this shit happens to people. Keep coolant in it, watch for leaks and monitor the gauges when you drive.

[69wannabe]

I bought the jeep with a bad engine and since it was a really different kind of engine I always kept an eye on everything as far as the temp gauge and oil pressure gauge. It was just a patched up head I believe, Nothing else was wrong with it best I could tell, after swapping it out and getting it back up and running it's all basically back to normal and running good again. I have to say I do like the WJ's a bit more than the old ZJ's even tho I have a 1993 Grand Cherokee my mom bought new and it has the 5.2 magnum in it and it's a 4wd so it's handy when it snows here. The WJ's seem to be a tighter design and the 4.0 is no problem to rebuild. Put the last one together in a few hours after I got it back from the machine shop. The 4.0 is a really versatile engine with good pep and torque and it isn't terrible on fuel mileage. Most of the one's I have had get around 18-20 mpg with normal driving. I have 2 WJ's at the moment, one with the 4.7 and one with the 4.0 so if one doesn't run hopefully the other one will :-) I just sold a really nice one that I had rebuilt for my daughter and she drove it for 5 years and decided to buy herself a newer car so I sold her old jeep since I got several extras already. They are pretty good vehicles and I was not a fan of the 05-2010 models at all. Bulky looking compared to the WJ's IMO.....