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Unread 05-26-2011, 02:42 PM   #1
skysthelimit001
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1987 YJ Wrangler 
 
Join Date: Apr 2011
Location: sound beach, new york
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rebuilt knock...deep in wallet, motor and not yet in mudd

3 months ago i bought an 87 wrangler yj...i've been working on it ever since...after a few days i replaced some gaskets and the exhaust and noticed that the motor had a knock from the lower half....since then, i've bored out the block and installed every part brand new or reconditioned including: crankshaft, main and rod bearings, pistons, freeze plugs, camshaft and cam bearings, full gasket kit, harmonic balance, oil pump, etc....i fired her up late last night and there is still a knock about the same as it was before the rebuild slightly higher pitch....i'm so frustrated with it this jeep is fighting so hard i'm at a loss for what to do next...please any ideas would help

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Unread 05-26-2011, 06:30 PM   #2
tjjeepwrench978
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flex plate or crank rod bbearings
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Unread 05-26-2011, 06:34 PM   #3
tjjeepwrench978
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I just took a 99 wj I got my girl for 700 knocking bad pulled the pan replaced the rod bearings voila no knock2 bearings melted no scores 4 barely spun
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Unread 06-05-2011, 08:02 PM   #4
darren2569
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I have the same problem. I put a reman crank (from crankshaft rebuilders) in my 02 tj to try and fix a low oil pressure problem. Right off it would knock real bad at the back of the engine but sound fine when it warmed up - still had low oil pressure.

SO I just replaced the crank again (same brand kit) along with cam and cam bearings. Oil pressure is great but I still have bottom end knock except this time it doesnt go away when the engine warms up.

Sorry to Hijack but I'm wondering if its a case of reman cranks being junk???
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Unread 06-05-2011, 09:10 PM   #5
tjjeepwrench978
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low pressure

your wrist pins might be knocking knock=play somewhere go get a 97 up nvh motor pull the head put your 02 head on much cheaper, good 97 anup 4.0s go for 150-400 around here My xj has 200 dollar 98 zj motor 3 race seasons on it cant kill it
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Unread 06-06-2011, 01:14 PM   #6
leftlanetruckin
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Did you get the rods checked for no runout etc?
I rebuild Rover V8's, and have yet to see a rod perfectly round on the big end bearing side. There is always some runout in them. Last set were all 1.5 thou out of round....
If you got new pistons, they should have come with new wrist pins, so that should be a moot point.
Did you Plastigauge the bearings?
Measure the ID of the main bearing caps?
Check for run out on the caps?
Get the block line bored?
Funny how folks think they can rebuild a motor by just throwing some new parts at it
If there is a knock, it isn't right. I suggest you stripping it all down and either measuring everything yourself, or have a machine shop measure everything.
I would hazard a guess that either a rod needs reconditioning (@$8 a rod, and cheap insurance), or the bearings have too much clearance due to not being measured etc.
This is how I rebuild a motor:
After a thorough cleaning...
Heads pressure checked and surfaced. Then all valves removed, relapped and new seals installed.
Block pressure checked.
Main bearing line bore checked and measured,block decked, crank ground for 10/10 bearings by torquing the bearings in the rods and mains, then grind the crank to the exact size of each bearing so no measuring needed, rods measured and reconditioned if needed, cylinders bored and honed for oversize pistons, new pistons, rings and wrist pins, all new galley and freeze plugs, new cam and lifters, new rocker shafts, then lovingly and accurately assembled.
Little more than just slapping parts together huh?
$900 in machine work alone, but the motors are bullet proof when finished.
Martin
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1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/f12/swap-offically-underway-324622/

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Unread 06-08-2011, 04:01 AM   #7
tjjeepwrench978
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funny ive owned a disco a rangie and a defender expensive on the parts and there 4.0 burns up exhaust valves on mobil gas
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Unread 06-08-2011, 08:59 AM   #8
leftlanetruckin
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I never bother with the 4.0's myself. But I have yet to see a burnt up exhaust valve from running different gas in any of the 4.6's I have done.
Funny thing is, the heads are the same
The total cost for parts to rebuild the 4.6's comes to @$1950, and that gets you a Crower cam and followers, pistons from England, FM bearings and Hastings rings, all new freeze and galley plugs, oil pump gears, and the OEM gasket set. Not overly stupid in my book. I could do them for a LOT less, but it isn't worth the potential fallback in my book
The Mk3 BMW motors I never really rebuild, as you can get a brand new long block from LR for just over $5k. For comparison sake, a SHORT block from Heep is just under $3k. So I dont think the LR price is too bad considering you are getting both heads and a multi valve V8 for another $2000.
Martin
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1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/showthread.php?t=324622

Years to gain the hands on experience, and offer it freely.
Minutes to gain the knowledge from the internet, and quote it just as freely.
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Unread 06-10-2011, 04:02 AM   #9
tjjeepwrench978
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golen in manchester sells 4.6 strokers 4 3500 only thing about the rovers is articulation of which the new ones have none
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Unread 06-13-2011, 12:23 PM   #10
skysthelimit001
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martin, what makes you assume i "threw parts" at my motor and called it a rebuild...u dont know who i am or what i put into this jeep...if throwing parts is what u call it when 4, 30+ year gm mechanics and i spent a month on this engine not to mention the 2 weeks that elsasser engines machine shop boiled and bored my block, pressed in cam bearings mic fit brand new pistons perfectly to each cylander...this jeep is now a monster the knock was from a dent in the oil pan that i overlooked, small problem and now its taken care of... i appretiate your advice but i think u should use a little less sarcasm in assuming ppl arent doing the right thing
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Unread 06-13-2011, 12:33 PM   #11
leftlanetruckin
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Have a look around and see what most call a rebuild, and you will see my point.
Glad you got it sorted, and that the issue was nothing internal so to speak.
Whenever someone gets defensive, as you just did, I just say the same old thing.....It wasn't me asking for help was it?
So with, in your words, 120 years worth of GM experience, plus your good self, no one noticed a dented oil pan?
Sorry bud, that's funny right there....
Regardless, it was a good (read free) result to a possible major issue.
If you cant take the ribbing on here, may I suggest Pirate for your evening entertainment. That will put it into perspective for you I think
Oh, and before I forget, you never did make a total breakdown of what you did to the motor All you said was every part was replaced etc. So there was no way of me knowing otherwise, as that certainly sounds like throwing parts at it to me.

Martin
__________________
1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/showthread.php?t=324622

Years to gain the hands on experience, and offer it freely.
Minutes to gain the knowledge from the internet, and quote it just as freely.
Choose wisely!
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Unread 06-13-2011, 02:46 PM   #12
skysthelimit001
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1987 YJ Wrangler 
 
Join Date: Apr 2011
Location: sound beach, new york
Posts: 11
i appreciate u taking the time out to give suggestions and try to help, and everyone who responded....i don't mean to b defensive its just that theres so many jo shmo's out there who think their the best mechanics around and sometimes are to quick to talk negatively and assume things aren't being done right....

not noticing the oil pan was my fault, and i'm not ashamed b/c i'm not a mechanic the guys giving me a hand aren't responsible for that they were just helping which is big part of what jeepin is all about not scrutinizing the use of the word rebuild...

and if what i did isnt a true rebuild than your right i dont kno what is
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Unread 06-14-2011, 06:09 AM   #13
leftlanetruckin
XJ on 37's
 
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Sounds like you got it pretty much covered to me.
I always check the line bore on the mains, and I would think that you had this done too, or at least the machine shop did it on your behalf.
I am far from the worlds best mechanic etc, but I do get anal where a motor rebuild is concerned.
There are a few companies also rebuilding the Range Rover motors that I do myself. Lost a few customers to them, as they are @$1K cheaper. But then you look at the specs and it all makes sense...
"New piston rings fitted" equates to the cylinders not being bored, nor new pistons installed.
"Crankshaft checked" equates to them just measuring the journals, maybe.
See what I mean? I wouldn't call a motor rebuilt if it had the original pistons in it, and so on.
Different folks have a different definition of a "rebuild".
Looks like you have it covered though, as I said earlier.
Glad you sorted it out, and the price was right!

Martin
__________________
1998 XJ on 37's.JK Rubi axles with chromo shafts and ctm's, 4:1 transfer case, etc etc etc.The Cherylkee....
2003 Range Rover HSE, 4.4 Quad Cam.
1998 Range Rover 4.6 HSE
2000 4.7 4WD WJ with a rebuilt motor.
4.3/700r4/new frame buildup (YJ)....
http://www.jeepforum.com/forum/showthread.php?t=324622

Years to gain the hands on experience, and offer it freely.
Minutes to gain the knowledge from the internet, and quote it just as freely.
Choose wisely!
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