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If you had a rod knock, what would you do?


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My options right now are:

Sell it

Drop in a used/rebuilt 4.0

Drop in a 4.6 stroker

Mod a 5.3 in

Mod a 4bta Cummins in

or...?

I vote "or."

 

The simple option you omitted is to drop the pan and install new bearings. Getting the pan off the first time is a nuisance but, overall, this is an easy fix. Do the rods and mains, and the rear main seal all at the same time.

 

 

Thing is, if the engine is high enough mile to be in such bad shape, a re-bearing isnt going to fix much. Usually new bearings on old journals will seize up anyways. I mean some get lucky and it works but that depends on the integrity of all the parts involved. If the rods big end is mis shapen due to the knocking/reason it ate the bearing... its just gonna lock up as soon as its warmed up and then it will throw a rod.

I don't suggest slapping new bearings on old journals.. ever.

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Thing is, if the engine is high enough mile to be in such bad shape, a re-bearing isnt going to fix much. Usually new bearings on old journals will seize up anyways..

Nope.

 

This is a VERY common procedure on Jeep 4.0L engines at around 200,000 miles. It always lasts until the owner either sells the vehicle or decides to build a stroker.

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Thing is, if the engine is high enough mile to be in such bad shape, a re-bearing isnt going to fix much. Usually new bearings on old journals will seize up anyways..

Nope.

 

This is a VERY common procedure on Jeep 4.0L engines at around 200,000 miles. It always lasts until the owner either sells the vehicle or decides to build a styroker.

 

 

lol...just because its common doesnt mean its right. grapes of wrath engine repairs goin on over here. :rotfl2:

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swap, swap, swap,swap,,,

 

Anybody fix anything???

 

Find out what the problem is first....................................

 

Then FIX it..

 

As others said if an auto check the TQ converter bolts. Knocks can come from many different places and rods are only one of them. Rod knocks are consistant in what they do.

 

Louder on a warm engine and also under load. Quieter on a cold engine and while coasting in gear or coming down in rpm. Very consistant in tone and repetition at a steady rpm. Anything erratic in an engine knock is usually not a rod/main issue. Worn bearings are changed all the time on engines without issue. If it is a rod and the crank/rod are still OK changing a bearing isn't a problem.

 

I've seen loose flywheels, TQ converters, transmissions, pulleys, timing gears, and many other things that people thought was a rod going out.

 

Find out what the problem is before you decide how to fix it.....

 

1 wrench and 20 minutes of tightening may solve the problem.

 

opsled

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Nope.

 

This is a VERY common procedure on Jeep 4.0L engines at around 200,000 miles. It always lasts until the owner either sells the vehicle or decides to build a styroker.

Don't you mean storker Eagle? :D

Fixed it. Danged Dell mushy keyboard.

 

I probably had "Stryker" on the brain.

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Find out what the problem is first....................................

 

Then FIX it..

 

As others said if an auto check the TQ converter bolts. Knocks can come from many different places and rods are only one of them. Rod knocks are consistant in what they do.

Also, if it's an auto, check the flex plate. They like to develop an annular crack, and the resulting clunk sounds a LOT like a rod bearing.

 

The test is to start the engine in neutral and let it idle. Blip the throttle (gently, don't floor it) and let it drop back to idle again. If you hear the noise, that's step one.

 

Put the tranny in drive with the brakes on. Give it just a tiny bit of gas, to put a small load on the torque converter. If the noise STOPS, there's a very good chance you need a flex plate.

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When mine started knocking my oil light would come on at idle after a drive to town go off when under acceleration the knock got so loud in about a months time people at stop lights were staring. My dad is a old retired mechanic said it was bearing for sure. I needed the old pan when I put the new motor in and it had 1/4 inch of bronze bearing material caked in the bottom of the pan. Motor is laying on the floor in the garage someday I will see how bad it it is. A local garage I go to for tires knows the truck and said it was a Chrysler rebuild with around 5k on it so something went wrong.

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Gonna reply to as many as I can remember since I'm on my phone. My truck is a 5-speed so that throws out the automatic diagnosis. As far as the power, it has none. I lose power going up hill, to the point where I dropped 10mph going up a decent hill, with the pedal to the floor. And the knock remains consistent and gets louder as the engine warms and rpms go up. Not "sure" it's a knock, but it's louder at the bottom side of the engine, and sounds very much so like something smacking.

Might try and get a video of it if it turns out right.

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Nuke, I did not. I will go check that today if I have time before heading out.

 

Got a video, not the best quality, but oh well. I could not get it with changing RPMs, as the only way pick up the noise with my phone was being under the truck. If I was above, you could only hear the whistling from the cold air and fans.

-6nufE_ukTU&feature=plcp

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As far as the power, it has none. I lose power going up hill, to the point where I dropped 10mph going up a decent hill, with the pedal to the floor.

You do realize that they put transmissions in vehicles so we can change gears, right? Sorry to be sarcastic, but there's a perception among (primarily) younger drivers that once you hit 5th gear you should never have to downshift unless you get to a stop sign or red light. Think about what an automatic would be doing on those same hills -- more than likely, downshifting, right? Then consider that an automatic has 3.55 axle gears and your 5-speed has 3.07 axle gears.

 

Needing to downshift when going up "decent" hills is a normal part of driving and does not necessarily indicate a problem with the engine.

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As far as the power, it has none. I lose power going up hill, to the point where I dropped 10mph going up a decent hill, with the pedal to the floor.

You do realize that they put transmissions in vehicles so we can change gears, right? Sorry to be sarcastic, but there's a perception among (primarily) younger drivers that once you hit 5th gear you should never have to downshift unless you get to a stop sign or red light. Think about what an automatic would be doing on those same hills -- more than likely, downshifting, right? Then consider that an automatic has 3.55 axle gears and your 5-speed has 3.07 axle gears.

 

Needing to downshift when going up "decent" hills is a normal part of driving and does not necessarily indicate a problem with the engine.

Yes, I do indeed realize that I'm supposed to downshift, and have no problem downshifting... that's how I was taught. But, there is no reason that I should need to downshift. My friend with a 91 V6 yota on stock axles and 33s would take that hill in 5th gear and keep accelerating, and his truck was a pile. Same with my friend running a 4 cyl ranger that is gutless as can be. He takes that hill in 5th gear no problem. EDIT: I understand that there are many many differences between my truck and these, just using them as reference points.

It's not the downshifting that's the problem, it's the what FEELS like lost power to me, along with the engine noise that concerns me. Yes, the gearing could (and most likely is) a huge part of that. But, the truck just feel like it has all it's gusto when climbing that hill.

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gearing is the problem. 3.07 gears suck and should never have been put in a Jeep. changing axles to even just 3.55s will make a significant improvement in the seat-of-the-pants feel. 4.10s would be even better. When I bought my 88 it had tiny little 215 tires on it. swapping to "monstrous" 30 inchers tires made it suck on the freeway, on hills, at stoplights, etc. when I blew up the rear axle I got a 3.55 to replace and the truck just came alive and was a joy to drive again! :yes:

 

 

I promise a better ratio will get you smiling again. :D

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gearing is the problem. 3.07 gears suck and should never have been put in a Jeep. changing axles to even just 3.55s will make a significant improvement in the seat-of-the-pants feel. 4.10s would be even better. When I bought my 88 it had tiny little 215 tires on it. swapping to "monstrous" 30 inchers tires made it suck on the freeway, on hills, at stoplights, etc. when I blew up the rear axle I got a 3.55 to replace and the truck just came alive and was a joy to drive again! :yes:

 

 

I promise a better ratio will get you smiling again. :D

Got offered to swap over to axles with 4.10s for free, so I will DEFINITELY do that. Did you listen to the engine noise video? Thoughts? Still think it sounds like a piston skirt, personally.

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I can't tell for sure what that noise is. but it's a pretty straightforward project to drop the pan and poke around. a great opportunity to change the rear main seal if it's leaking. be certain that the back of the valve cover isn't leaking (it's pretty common) because a leak that will dribble down and look like a RMS.

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Yes, I do indeed realize that I'm supposed to downshift, and have no problem downshifting... that's how I was taught. But, there is no reason that I should need to downshift. My friend with a 91 V6 yota on stock axles and 33s would take that hill in 5th gear and keep accelerating, and his truck was a pile.

Could be gearing. My brother had an early 90's Nissan 5-speed V6pickup that had (IIRC) 4.11 gears from the factory. He now has a somewhat newer Nissan 5-speed 4-banger and I think that has 4.56 gears.

 

You could also have a clogged catalytic converter.

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Got offered to swap over to axles with 4.10s for free, so I will DEFINITELY do that. Did you listen to the engine noise video? Thoughts? Still think it sounds like a piston skirt, personally.

The video sounded to me like a rod bearing. But ... I can't say that I've ever heard piston slap, so I don't think I could tell the difference.

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Sounds like a rod bearing to me too. My old motor developed the exact same noise before I pulled it. It would get louder when you applied the gas ever so slightly. When you accelerated under more of a load the noise would go away. When you slowed down to an idle or just above the noise would come back. I drove it for a couple days and wondered if my torque converter bolts were getting loose and hitting the bell housing. I made sure they were tight and they were. I laid under the truck and it sounded like it was #6 rod bearing at the very back of the motor because it sound like something was hitting the oil pan. I parked it and decided to swap motors and inspect it since I already had the stroker on the engine stand in the garage.

 

The oil from the motor goes from #1 through #6 in that order so if oil starvation ever were to happen it would most likely be #6 since it's at the end of the line. If it was a main bearing it would loose oil pressure. If it were a cam bearing you would hear no noise just loose oil pressure. Main bearing noises are usually a much deeper tone of noise or knock. I'll find out what mine was when I put it on the engine stand and flip it. I drained the oil and found no metallic so who knows.

 

I wouldn't drive it, you can prolong death if you put some additive in the oil to cushin the bearings. Lucus would do it, just use 5.5 quarts of 10-W30 oil and one bottle (1qt) of lucus.

 

I hope this helps, thanks for the video. That really helps!!

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So it seems the general consensus is to not drive it (lol! good luck with that :rotf: ) until I can replace or repair. Haven't dropped the pan yet, and may never do so. We shall see how soon I can get a new engine.

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