picked up a 99, grand cherokee laredo, 130k miles on it. not running. has the 4.0l 6cyl in it. got it, not running, said it had a knock, n antifreeze in the oil. drained 1 gal of antifreeze out of the oil pan,, and found number 4 cyl,, with a broken electrode off the spark plug. motorcraft platinums, with a long reach electrode is in it now. service records were in the glovebox, oil changed at regular invervals at a dealer, found k&n filter n oil filter on it too. i turned the engine over by hand,, n itll lock up, i can see some rust in number 4,, gonna pull the head off it later on, n see what i find. bettin wrong plug application, n im gonna find that electrode imbedded in the piston n lots of dents in the head aint i? body looks like a dodge durango. been in a garage for 3 years till i got it. they say them 4.0 will run forever. lol.
- Thread starter ss409
- Start date
I've got a 96
That's not long enough to call it "forever", but I've got no complaints so far.
It's got the 6 cylinder - has a trans leak from the front seal I believe - I've been keeping it topped off - maybe a half a quart every couple of months. But the seal seems to have healed itself.
No new drip marks on the driveway lately.
That's either lucky for me, or a REAL bad sign
Other than that, only minor normal problems. oxygen sensors, alternator, waterpump, etc. All simple repairs - very easy engine to work on.
That's not long enough to call it "forever", but I've got no complaints so far.
It's got the 6 cylinder - has a trans leak from the front seal I believe - I've been keeping it topped off - maybe a half a quart every couple of months. But the seal seems to have healed itself.
No new drip marks on the driveway lately.
That's either lucky for me, or a REAL bad sign
Other than that, only minor normal problems. oxygen sensors, alternator, waterpump, etc. All simple repairs - very easy engine to work on.
engine bay is super clean, the whole truck is like new! been watching on you tube videos, seen where they have lifter issues, and possibly a cyl head weak area prone to crack near number 4. making this tractor related, the 4.0 reminds me of a 310 oliver gas engine. 12 port head, but with a counterweighted crank. lol. heard a guy could put in the 258 crank n rods in the 4.0 for a cheap stroker. was thinking that repair/upgrade if number 4 journal cant be fixed. i probably will hope to be able to fix it right if she can be fixed right. what kind of milage do these get? no idea what gear ratio it has. thanks.
mileage on mine isn't great, but a lot better than my truck.
The little computer thing tells me I average 16.x mpg - not sure how accurate it really is, I've never tested it.
Only bad thing I've heard of these is that the transmission is on the weak side if you're going to be doing any towing. Talking about the 96 of course, not sure what changed for 99.
All I tow with it is a small horse trailer full of goats - nothing too heavy. No trouble pulling that.
Not sure how many miles I have on mine - probably a little less than yours. I had it off the road for several years. No real reason, just didn't need it.
If you do that upgrade to your engine, I'd like to hear about it...
... if you can compare it to rebuilding a tractor engine that is.
The little computer thing tells me I average 16.x mpg - not sure how accurate it really is, I've never tested it.
Only bad thing I've heard of these is that the transmission is on the weak side if you're going to be doing any towing. Talking about the 96 of course, not sure what changed for 99.
All I tow with it is a small horse trailer full of goats - nothing too heavy. No trouble pulling that.
Not sure how many miles I have on mine - probably a little less than yours. I had it off the road for several years. No real reason, just didn't need it.
If you do that upgrade to your engine, I'd like to hear about it...
... if you can compare it to rebuilding a tractor engine that is.
Gambles
Well-known Member
Starting in ABOUT '99, the 4.0 went to the 0331 cylinder head. (previously they used the 0630 head) The 0331 heads are prone to cracking. Jeep/Chrysler didn't get this head fixed for several years. I would take the head off and get it checked for cracks. If it was mine, (and it's not remember) and you found you had the 0331 head, I would probably take it off and have a new one put on. Resist the urge to put on a used 0331 head. There are new replacements still on ebay that will fix this. These heads will probably be made in Brazil or China, but they are good replacements that are not prone to cracking.
BTW, I have two '96 4.0 Jeeps with the 0630 head that I've had to replace because both cracked. Supposedly, these are the good crack-resistant heads and they haven't been overheated.
The Jeep 4.0 has a cult following that says it's a good engine, and it is. It's just not as good as the old Ford 4.9 six.
BTW, I have two '96 4.0 Jeeps with the 0630 head that I've had to replace because both cracked. Supposedly, these are the good crack-resistant heads and they haven't been overheated.
The Jeep 4.0 has a cult following that says it's a good engine, and it is. It's just not as good as the old Ford 4.9 six.
ive seen the heavy duty cyl heads. thats probably in the plan to upgrade the head. no telling what im gonna find in that rough cyl. can that head crack so bad that it could fill up the middle cyls n then hydrolock the cyl n break the plug electrode off? number 4 is the only cyl i see with visable damage looking thru the plug hole. previous owner said she started knocking then the water showed up after a service at a dealer. he quit driving it when it died i guess, so no tellin the damage. lol. now, didnt these same trucks have dodge V8s in em? wife calls this truck the laredo durango cause the bodys r spitting images. lol. its stock suspension is in good shape, but thinking it be nice with a 2 in lift. not much, just enuff to lift the nose to where she sits level.....
My daughter has '98 Cherokee (not Grand) with the 4.0 in it. She bought it up in VT and I thought she got took, had a little over 100K on it and didn't look like it was well taken care of. Had some issues - A/C comp, P/S pump, had to replace a front wheel bearing and ball joints... but she just cracked 200K with it and it's still running strong, so I guess she showed me up...
from what i understand, the 258ci from the mid 80s, the crank, and rods, with the stock 4.0 pistons make a cheap stroker setup for the 4.0. close to 300hp n good torque to 4000rpm. to make it tractor related again, its like putting a 265 crank in a 251 flathead chrysler for a homebuilt 265ci motor. did that once, n made a good power improvement.
Gambles
Well-known Member
If you actually have the 0331 head, it will probably crack in cylinders 3 or 4. First check to see if you have the 0331 head. The casting will be about in the middle of the head between on the driver's side right between the intake/exhaust manifold and the valve cover.
I hope you didn't pay too much for this Jeep. It's possible it will need a lot more repair than you think.
I hope you didn't pay too much for this Jeep. It's possible it will need a lot more repair than you think.
Noooo! didnt give much for it at all, and it cleaned up very nice. not one spec of rust, its been garaged everyday since 02, drove 40miles a day everyday till 09 then this happened n she sat in the garage till i found it thru a mutual freind. service records was in the glove box from 02 to 09. ill pop that head off n report back.
Anonymous-0
Well-known Member
Had a 1973 international 1310 seires truck and it had the 258-6.It was a good engine and it started good in cold weather. The only problem I had was the lifter wanted to clatter after a new oil change. Found out that if I added a quart of Marvels Mistery Oil at every oil change I had no problems.
huntingreen2day
Member
I had a 97 GC. It had 150K on it when I got rid of it. At 40K rear end got noisy. I replaced the bearings which cured it for awhile maybe 5K miles so I just let it go and turned up the radio. pulled a boat a lot with mine. Replaced the water pump, AC compressor, radiator, PS Pump while I had it most of that in the last year. Never had any internal engine problems.
Super Steve
Member
its a bit more complicated then that but yes you can build a "not-so-cheap" stroker by putting those parts together. Back when i was in the jeep world, i knew a few guys that had done this and regretted every minute of it. way more cost than its worth. Most of them said i they were to do it again, either upgrade to a v-8 or buy a complete prebuilt high performance 6 cyl 4.7 stroker engine
Rollie NE PA
Well-known Member
I have had 3 Jeeps with the 4.0. Two went over 250,000 until the bodies rotted away.
My wifes 2002 4.0 has 140,000 miles. I have a 2000 Limited with the 4.7 V8. I replaced the engine at 84,000 miles. What a job that was.
I have never had to do anything with the transmissions or rears oon any of them.
My wifes 2002 4.0 has 140,000 miles. I have a 2000 Limited with the 4.7 V8. I replaced the engine at 84,000 miles. What a job that was.
I have never had to do anything with the transmissions or rears oon any of them.
havent got the head off it yet, does have the 0331 head, but no visable cracks on the outside. manifolds r fun to remove! that tells ya how close we r to pulling the head, had other work to do yesterday otherwise id be reporting what i found. lol. so far, its clean inside the valve cover, no loose rockers, and every bolt is comming apart easy. this will be my 3rd jeep. had a 83 cherokee 2dr, and a 79 j10 pickup, now this 99. the other two never let me down, so hoping once the 99s problem is revealed, hope its not beyond fixin. nobody has a 4.0 in the yards here!
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