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Discussion Starter · #1 ·
Hey all. I just bought my YJ yesterday, and it turns out it has what sounds like a low end knock of some sort. I can feel it when I touch the oil pan, so I'm positive that's where it's coming from. It doesn't do it for the first few minutes when it's cold, starts quiet gets louder after five or ten miles. The guy I bought it from said he had the whole top end rebuilt less than 1000 miles ago, so I suppose replacing the whole engine might not be worth it. Anyone know roughly what it costs to rebuild the lower end, or maybe recommend a good mechanic in the Seattle area?

Thanks in advance!
 

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I haven't lived in Seattle in 22 years, so cannot help with that; but the parts will probably be about $500+ and expect about $100/hour. Last rebuilt motor I bought was $1500, but it was not a Jeep. I think short blocks, (what youre asking for) are typically about 600 to 1000 depending. For that kind of money you can easily get a used motor, in good shape, and have it replaced. Or if you dont mind waiting till spring I could come over and give you a hand replacing it. :D Should only be a few hours to remove and reinstall a motor; the tricky time consuming part are all the cables, hoses, and accessories to put on the replacement motor.

Lots of possibilities to think about, but my preference would be to rebuild what you have, then buying another good motor would come in second. Sometimes you can get a good replacement motor, complete, from craigslist or some such for only a few hundred or so.
 

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Discussion Starter · #5 ·
I haven't lived in Seattle in 22 years, so cannot help with that; but the parts will probably be about $500+ and expect about $100/hour. Last rebuilt motor I bought was $1500, but it was not a Jeep. I think short blocks, (what youre asking for) are typically about 600 to 1000 depending. For that kind of money you can easily get a used motor, in good shape, and have it replaced. Or if you dont mind waiting till spring I could come over and give you a hand replacing it. :D Should only be a few hours to remove and reinstall a motor; the tricky time consuming part are all the cables, hoses, and accessories to put on the replacement motor.

Lots of possibilities to think about, but my preference would be to rebuild what you have, then buying another good motor would come in second. Sometimes you can get a good replacement motor, complete, from craigslist or some such for only a few hundred or so.
Thanks for the insight! I'm thinking a rebuilt block at this point. Do you ever make it out this way?

no,but I would not run it anymore before I tore it down
Thank god I have my motorcycle!

+1

If you're mechanical at all, you could just pull the pan and see what the problem is.
Absolutely. I live in an apartment complex, so I just need to find a place to do it. If it's just a rod, would it be a bad idea to just replace the rod and call it a day? It has 156k on it.... Is that about the time they start to go?
 

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Thanks for the insight! I'm thinking a rebuilt block at this point. Do you ever make it out this way?



Thank god I have my motorcycle!



Absolutely. I live in an apartment complex, so I just need to find a place to do it. If it's just a rod, would it be a bad idea to just replace the rod and call it a day? It has 156k on it.... Is that about the time they start to go?
Honestly, if you lost a rod you would need to tear it down, have the crank and rod(s) checked and machined as necessary AT A MINIMUM. Now I have done things like that, but I wouldnt recommend it unless you dont care how long it lasts. But since youre already there, you might as well rebuild it all since at 156k its all pretty worn anyway. Just depends on time, money, and what you realistically expect.

You would need new rod and main bearings, and if you had the money replacing the rings would not be too much extra. You can glaze hone the cylinders and probably get away with that too as a "poor mans" rebuild. But then the cam would be your next weak link.

Some motors last a long time, some not so much, at 156k its not completely worn out. If not for this problem you could have gotten many more miles out of it. Mine has 190k, on an '87 4.2L, assuming the previous owners havent done any engine work, its burning oil and doesnt have a lot of power, but it still gets around.
 

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Oh, and typically dont get to Kent much; mostly the north end. Monroe, Everett, Lake stevens. But we try to make a couple or so trips to the west side, the trick would be having a place to work, and all the tools necessary to do the job. Tools arent too much of a problem as long as I dont forget some; but the place and the "what ifs" can burn you. Last summer I had to replace the axles, and it was supposed to be a day or so down time, but I had to order brake parts that I wasnt prepared for, and manufacture some brake lines. that added a few more days.

If you go for a tear down project, the machine work will kill you price and time wise. Generally its about the same as a rebuild kit, so it you expect about $300-$400 depending. You probably would be better off finding a short, or even long block, all ready to go.
 

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Discussion Starter · #8 ·
Thanks Camarozz! I think I'm leaning towards the long block idea. I'm finding them around $1200. Do you know of any reputable reman/used engine suppliers? I've been digging around the internet for hours now, and can't seem to find a place that seems legit.

I understand not comming around the south end very often. I'm not a big fan.... Probably going to be moving up to Lynden in the next year or so, and I can't friggen wait! I hear there's some great trails up there too!!
 

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Other than timing, and depending on how fast you want this done, I could be available in the spring sometime; we may be able to work something out.

As for the engine, my preference is to stay away from the Autozones, O Rileys, and the like. I have a good Napa over here, but its just a machine shop, and in Wenatchee is Jerry's that I would trust; You should have plenty to choose from over there, but take your time and ask questions, see if any of your friends have any experience with someone.

Wow, Lynden, that'll be quite a different place. :) North Cascades is beautiful for sure.
 

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Discussion Starter · #10 ·
Other than timing, and depending on how fast you want this done, I could be available in the spring sometime; we may be able to work something out.

As for the engine, my preference is to stay away from the Autozones, O Rileys, and the like. I have a good Napa over here, but its just a machine shop, and in Wenatchee is Jerry's that I would trust; You should have plenty to choose from over there, but take your time and ask questions, see if any of your friends have any experience with someone.

Wow, Lynden, that'll be quite a different place. :) North Cascades is beautiful for sure.
Yeah, I'm going to have to do this pretty quick. After taking a closer look, I think it might just be a crank bearing. Should be a pretty easy fix if that's the case.

I agree about the Autozones and whatnot. For me they are just a place to get Armor All, bulbs and floor mats. Sometimes you get people that know what they're doing, but it's unusual. I've actually been having a hard time finding good shops around here. I did find a long block with a three year warranty for $1200 shipped! If it's a rod I'll be going that rout.

Yeah, I'm really looking forward to Lynden. I grew up in a small town just like it, and I'm stoked to get away from the city!
 

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are you keeping the old motor, or sending it back for core? (assuming there will be a core charge).

$1200 sounds very reasonable, especially shipped. Is it a local company?

I understand the city thing; I could only handle Seattle for 5 years before I made a bee line over here.
 

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Discussion Starter · #12 ·
I'd like to keep it for parts, but don't really have the space. That price doesn't include core. I'll probably Craigslist it or sell the head and carb, then recycle it. I'll burn that bridge when I get there. Let me know if you need anything off it!

Five years is exactly how long I made it..... I'm feeling pretty checked out at this point! Ha ha
 

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Yeah, actually... if you dont have to send the motor back for a core then I may be interested in the whole motor. Mine is burning oil real good, and with over 180k on the clock its time to tear it down. But again, that may be a spring time project. :)

Although, you will probably need the carb, intake, exhaust, distributor, starter, flywheel, and possibly even the oil pan depending on the rebuilder. :D
 

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I'll will prob be buying a rebuilt motor myself...come spring. I have an 89 4.2 with 204xxx still runs very good, not burning oil n hot power. It did have a knock sometimes on start up but not anymore thanks to Lucas stabilizer. Also sounds like a diesel running ha because the lifters make noise. I do wheel it regularly too. Should get through winter though. A fresh 4.2 to start with would be awesome...I love the motor...very tough n reliable I say! I have seen reman engines also with the 3yr warranty...same on eBay with free shipping, I don't remember the company at the moment.
 

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Low end knock

I just bought an 88 YJ not running and when I first got it running I had the same knocking at the low end, at first I tough is was a bad rod but after checking more I found that the knocking was coming from the mechanical fuel pump, I went ahead and open the engine bottom and check the oil pump and it was good, all rods where good, just the time chain was a bit too loose so I put a new one and new water pump and problem was solve. Not sure if your has the same problem but is worth checking, not a whole lot of money to fix...good luck

Hey all. I just bought my YJ yesterday, and it turns out it has what sounds like a low end knock of some sort. I can feel it when I touch the oil pan, so I'm positive that's where it's coming from. It doesn't do it for the first few minutes when it's cold, starts quiet gets louder after five or ten miles. The guy I bought it from said he had the whole top end rebuilt less than 1000 miles ago, so I suppose replacing the whole engine might not be worth it. Anyone know roughly what it costs to rebuild the lower end, or maybe recommend a good mechanic in the Seattle area?

Thanks in advance!
 

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Discussion Starter · #16 ·
Yeah, actually... if you dont have to send the motor back for a core then I may be interested in the whole motor. Mine is burning oil real good, and with over 180k on the clock its time to tear it down. But again, that may be a spring time project. :)

Although, you will probably need the carb, intake, exhaust, distributor, starter, flywheel, and possibly even the oil pan depending on the rebuilder. :D
Yup, probably going to need that stuff, but if I go that rout, I'll definitely let you have what ever I don't need. It has good compression and plenty of power. It has the Weber 38/38, and I'm switching back to the factory intake system due to emissions. I also think the guy didn't do a good job, cause I'm getting like 7 MPG and I smell gas pretty bad. I'm not the carb expert, but he definitely half assed it!

I'll will prob be buying a rebuilt motor myself...come spring. I have an 89 4.2 with 204xxx still runs very good, not burning oil n hot power. It did have a knock sometimes on start up but not anymore thanks to Lucas stabilizer. Also sounds like a diesel running ha because the lifters make noise. I do wheel it regularly too. Should get through winter though. A fresh 4.2 to start with would be awesome...I love the motor...very tough n reliable I say! I have seen reman engines also with the 3yr warranty...same on eBay with free shipping, I don't remember the company at the moment.
Sounds like it might be time for for ya bud! Having a fresh power plant would definitely be a weight off the ol' noggin!!
 

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Discussion Starter · #17 ·
I just bought an 88 YJ not running and when I first got it running I had the same knocking at the low end, at first I tough is was a bad rod but after checking more I found that the knocking was coming from the mechanical fuel pump, I went ahead and open the engine bottom and check the oil pump and it was good, all rods where good, just the time chain was a bit too loose so I put a new one and new water pump and problem was solve. Not sure if your has the same problem but is worth checking, not a whole lot of money to fix...good luck
Thanks for the insight bud! I found a trusted shop close by, and I'm taking it there on Friday to have a professional opinion. The funny part is, it doesn't knock when it's cold, only when it approaches operating temp, and that's what leads me to believe it's a bearing. We shall see! It also doesn't knock under hard acceleration. Any ideas? Thanks!
 

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Oh, I assumed it continued to knock no matter what.

So you are saying the knock subsides under acceleration?

Does it immediately start to knock as you let off the gas?

Possible piston slap, or timing chain is another failure. Usually a knock will not go away and will get significantly worse the more its driven. Although no knock when its cold does jive with bearing. Also its possible that a lifter or something in the valve train is failing/loose.

Hows your oil pressure?

Really, the only way to tell is to start tearing it down; the pan would probably be easiest and quickest, but thats only if you just want to know what the problem is.
 

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Discussion Starter · #19 ·
Yup, it goes away under load, and lessens a little when I let off. I mostly knocks at idle, and under light load (warm only). If it was piston slap wouldn't I lose compression in that cylinder? I have a receipt from a shop the previous owner took it to, that says the timing chain and gears were replaced, as well as the water pump and various other items. But that same mechanic said "It's just a sound the timing chain makes, and always will" (which sounds like a load of crap to me) I just got off the phone with him, and am left seriously questioning his level competence!
 

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Can you record the sound and post it?

I would not believe a timing chain should sound like you describe unless it is loose; and if it is a new chain and its loose like that, then that is not normal.

Piston slap does not always include a decrease in compression. I doubt it is that, but Ive seen odd things before. It could be a broken skirt on the piston making it sound like that, but I would suspect it would sound the same at idle as well as under load.

You could take the jeep out and hot rod it around for a while, then I bet you would find out what the problem is when it breaks. :D
 
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