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Unread 11-17-2012, 12:45 PM   #1
snowrydr01
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blew up engine...where to start

background:

I was loosing oil but never had a puddle or a singe visible cloud of smoke so i figured exhaust valve seals and replaced the head and it ran great. Today on the way to wheeling i checked the oil and it was good and 50 miles later BOOM, pull over and theres no oil. The jeep behind me says it was smoking most of the way. With a new head on the only thing i can think of for burning oil would be bad piston rings or cracked blocked leaking oil into cylinder.


Anyway....now i have a 4.0 that sounds like there are marbles rolling around it with and all the coolant has leaked out. Although i cant find where its coming from since its coming out by the dust sheild.

So next weekend im going to pull it and put it on the engine stand. Im very mechanical but have never done any real engine work before besides head swaps are those are pretty straight forward.

Where do i start to find out what i actually need to replace and fix? Money is a bit tight so a stroker or upgrading parts i dont NEED to are out of the question.

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Unread 11-17-2012, 06:02 PM   #2
wushaw
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A used motor would be cheapest & fastest way to get ya going.
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Unread 11-17-2012, 06:59 PM   #3
dkrajcovic
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look at the rod & main bearings
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Unread 11-17-2012, 09:07 PM   #4
MattJeep
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Ya swap in a used 4.0. Theres gotta be millions of them, I see them on Craigslist all the time. OR, even better, swap a V8 in!
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Unread 11-18-2012, 06:14 AM   #5
snowrydr01
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Originally Posted by MattJeep View Post
Ya swap in a used 4.0. Theres gotta be millions of them, I see them on Craigslist all the time. OR, even better, swap a V8 in!
I have 2000 so the window of oportunity for motors isnt as large as the pre 99s before the coild pack ignition.

Im pulling it next weekend.

I just its just to pull everything apart and check bearing surfaces for obvious scouring?

How can i determine if i nee to have parts machined or can use bearing of the stock size?

If there a list of what diameters should be? We have a substantial QC department at work (we make breaks for trains) so i can measure anything pretty accurately.

V8 or stroker is not really an option.....although getting that aw4 in thats been sitting in the garage sounds like the right thing to do
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Unread 11-18-2012, 06:17 AM   #6
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i figure ill definitely have to replace the push rods, rockers, and pocker pivots to get rid of the huge knock and hopefully the new head is ok
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Unread 11-18-2012, 08:22 AM   #7
rda616
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Quote:
Originally Posted by snowrydr01
i figure ill definitely have to replace the push rods, rockers, and pocker pivots to get rid of the huge knock and hopefully the new head is ok
It's doubtful these caused any of those problems. A tick would likely be a lifter, or maybe one of those you mentioned. A knock on the other hand is likely a rod bearing. You will likely need machine work. Block bored and line honed. The crank needs to be checked and likely ground if it was a spun bearing. If you are really losing coolant you could have windowed the block! If that's the case it's done and you cannot repair it.
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Unread 11-18-2012, 09:41 AM   #8
snowrydr01
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Quote:
Originally Posted by rda616

It's doubtful these caused any of those problems. A tick would likely be a lifter, or maybe one of those you mentioned. A knock on the other hand is likely a rod bearing. You will likely need machine work. Block bored and line honed. The crank needs to be checked and likely ground if it was a spun bearing. If you are really losing coolant you could have windowed the block! If that's the case it's done and you cannot repair it.
If it wasn't a spun bearing, why would it need to be line hones, I guess the same question goes for the cylinder wall, if no scarring why would I need a bore?

Where can I can find the number s to take measurements and determine?
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Unread 11-18-2012, 09:56 AM   #9
rda616
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Quote:
Originally Posted by snowrydr01

If it wasn't a spun bearing, why would it need to be line hones, I guess the same question goes for the cylinder wall, if no scarring why would I need a bore?

Where can I can find the number s to take measurements and determine?
It's always a good idea to have a machine shop check these things before you rebuild an engine. At a minimum you need to hone the cylinders with new rings. The chances are you will need to bore your block .010 to true the bore with a vehicle 12 years old with likely over 100k miles on the till. Your bore will egg shape with wear. You need to have that new head checked as well if a rod let go. You may have cracked the head, or bent valves. Google engine specs for the 4.0 for factory specifications!
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Unread 11-18-2012, 10:14 AM   #10
snowrydr01
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Quote:
Originally Posted by rda616

It's always a good idea to have a machine shop check these things before you rebuild an engine. At a minimum you need to hone the cylinders with new rings. The chances are you will need to bore your block .010 to true the bore with a vehicle 12 years old with likely over 100k miles on the till. Your bore will egg shape with wear. You need to have that new head checked as well if a rod let go. You may have cracked the head, or bent valves. Google engine specs for the 4.0 for factory specifications!
When googling 4.0 specs all I'm finding are reviews about power' torque, year differences etc, not really internal measurements?
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Unread 11-18-2012, 11:57 AM   #11
sailsurf7713
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A haynes or chiltons manual should have everything you need. If you need any particulars I can email you the pages from the FSM if you'd like. Just send me a PM.
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Unread 11-18-2012, 12:05 PM   #12
snowrydr01
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Quote:
Originally Posted by sailsurf7713
A haynes or chiltons manual should have everything you need. If you need any particulars I can email you the pages from the FSM if you'd like. Just send me a PM.
I have a 2000 FSM so if you could just give me the page numbers that would be a big help
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Unread 11-18-2012, 12:13 PM   #13
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If your going to do it, Do it right the first time.....
1. Don't try to go cheap, you'll just be doing it again.
2. Have a machine shop check everything, just because you think a cylinder is not scored it could be egg shaped from wear.
3. always have the line bore checked and bored if needed or you'll be doing it again soon.
4. Have the head magnafluxed. You wont know if it was cracked when it blew if you don't.

Again, Ask me how I know.....LOL
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Until it's done!
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Unread 11-18-2012, 02:43 PM   #14
snowrydr01
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Quote:
Originally Posted by jbmolly View Post
If your going to do it, Do it right the first time.....
1. Don't try to go cheap, you'll just be doing it again.
2. Have a machine shop check everything, just because you think a cylinder is not scored it could be egg shaped from wear.
3. always have the line bore checked and bored if needed or you'll be doing it again soon.
4. Have the head magnafluxed. You wont know if it was cracked when it blew if you don't.

Again, Ask me how I know.....LOL
we have an pretty serious qc department at work. I can check the round of the cylinder heads and dye penetrent test the heads myself.

I will have the line bore checked though and any other surfaces that look suspect.

I guess the first step is to yank it out and see what it looks like in there and what went BOOM in the first place.....it sounds like a tractor when i tried to start it on the side of the road
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Unread 11-18-2012, 03:12 PM   #15
wushaw
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Quote:
Originally Posted by snowrydr01 View Post
we have an pretty serious qc department at work. I can check the round of the cylinder heads and dye penetrent test the heads myself.

I will have the line bore checked though and any other surfaces that look suspect.

I guess the first step is to yank it out and see what it looks like in there and what went BOOM in the first place.....it sounds like a tractor when i tried to start it on the side of the road
Well if it sounds like a tractor then you should be good to go, I know my two diesel tractors run like sewing machines
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