rod bearing knock? would like some opinions please

Ok. I have done a ton of searching and reading on this the past few days and after reading about fifty threads I am pretty sure I have a rod bearing knock. I would still like some opinions on the knock being a rod bearing.
At startup I have no knock what so ever and oil pressure is at 60. There won't be a knock until it gets up to about 150 in tempurature and is barely audible at idle when I rev the engine to between 2000 and 3000 is where it is most noticeable. When the engine is at temperature, around 180, and oil pressure is between 20 and 30 pounds you can hear it good at idle. But when you rev up the engine it gets extremely loud!! Makes me cringe! I don't have an oil leak anywhere.
I am 95% sure that it isn't the flexplate. Delt with that already when replacing my engine. My oil pressure seems to be fine and temperature stays at 180 always. I never overheated the engine just gave her some pretty high rpm's once or twice. This engine runs excellent even with the bad knock so I don't want to give up on it yet. I have ran the engine in the garage a few times but never on the road since Memorial weekend when it happened.
Friend of mine is on the way to get some plastiguage so I can get started. Any thoughts or opinions are greatly appreciated. I have the carbed 2.5 inline four which is very simular to the inline six. Getting the pan off while in the jeep is not a problem. Let me know if you have any questions. TIA

Kim.

Well, I got the pan off a little while ago. I can slide the bottom of the rod back and forth on every cylinder. Can't move it up and down with my fingers though. Had some shavings in the oil. Had some shavings in the oil also. Could someone out there give me an opinion on what to do from this point? If it is not worth the time to replace the bearings from seeing the shavings then I don't want to continue with this. I will pull the motor and put in a different one. Any opinions are appreciated.

Kim.

Your rods are supposed to have a little side play on the crank. As for measuring the wear of the bearings the only method I know of is a plastiguage which you could do from underneath pretty easily. Perhaps someone else has some better advice.

Bender said:

Your rods are supposed to have a little side play on the crank. As for measuring the wear of the bearings the only method I know of is a plastiguage which you could do from underneath pretty easily. Perhaps someone else has some better advice.

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Thanks for the reply Bender. I will be taking off the bearing caps in a little while to see how they are. For some reason I just have a feeling that my knock isn't a rod bearing knock because of how loud it gets when warm. Anyone else out there with any ideas? Where are all the engine junkies out there? Thanks.

Kim.

well i say pull the caps one at a time, and look at the bearings, DONT MESS UP THE CAPS, they only go on 1 rod, in 1 direction!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a spun bearing will be very easily detected, dont even take the rods off the crank, just look at the bottom half of the bearings.....all scratched up and colors is bad.... post pics if you want, ill be more than happy to help ya out

tealcherokee said:

well i say pull the caps one at a time, and look at the bearings, DONT MESS UP THE CAPS, they only go on 1 rod, in 1 direction!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a spun bearing will be very easily detected, dont even take the rods off the crank, just look at the bottom half of the bearings.....all scratched up and colors is bad.... post pics if you want, ill be more than happy to help ya out

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Thanks for the help teal. I did alot of searching on this before I attempted it so I know a few things about it. Don't worry I will do this one bearing at a time. I will try to post some pics later tonight, that will be the first chance I get to post some if I am able to. I am going to go out and take one off and see what it looks like. I am still waiting for my plastiguage to get here. I will post with what I find.

Kim.

Ok. Got the rear cylinder rod bearing off and let me tell ya it doesn't look good at all. This picture is not very clear but you can tell where the severe damage is. on the top left where it is really bright that is where it lipped itself over pretty bad also. I hope the other ones aren't like that. The bottom of the rod seemed ok. I felt it and it was smooth for the most part. With this much damage to the bearing is there possibly damage elsewhere? That picture was taken with my cameraphone so it is not the greatest but at least it works.



Thanks everyone for the help.

Kim.

When you take the picture see if you can get a pix top bearing and the crank journals as well. You might get by with just a bearing swap, but you will need to mike things to tell. Some companies make .001" under rod bearings just for this reason.

When I first came back to the thread the picture was not there. But then I hit refresh and it was there. Try a refresh. I will try to get a picture of the journals.

Kim.

I tried to get a picture of the journals but my camera phone doesn't have a flash so it is a pretty crappy picture. With only replacing the rod bearings will this last me another couple trail rides? I don't dd this jeep so there won't be much on it for road miles. Just trails. I will replace the motor this fall, I just want it to last me some more trail rides. TIA

Kim.

im a hack w/ everything, but im super anal w/ motors, theres no reason to get a new motor, unless your doing a 242 swap or something, id just rebuild it, i blew my 4.0 on the trail, running mint now

as far as just replacing the bearings, it really depends, i wouldnt do it, get the crank machined, .010 under, and get the rods reconditioned.....

if your going that far, might as wel ldo the rest

tealcherokee said:

im a hack w/ everything, but im super anal w/ motors, theres no reason to get a new motor, unless your doing a 242 swap or something, id just rebuild it, i blew my 4.0 on the trail, running mint now

as far as just replacing the bearings, it really depends, i wouldnt do it, get the crank machined, .010 under, and get the rods reconditioned.....

if your going that far, might as wel ldo the rest

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I am going to be doing a rebuild and possibly a stroker type rebuild if I can find the right info. The rebuild will be done on my original since it is still in running condition. As far as replacing the bearings, I think I am going to just replace the rod bearings and see how long it lasts. I only need it to last a couple of trail rides so hopefully it will hold together until late fall.
This motor runs very good so hopefully it will last me. I will be staying with the 2.5 until the truck is not able to be driven anymore so a swap is out of the question. I like this size four cylinder. It has potential. Since I am only replacing the rod bearings, what size should I go with? Should I go with the normal size or go a size bigger? Also if anyone has ideas for a stroker build on a 2.5 let me know. Any ideas are welcome. Thanks all for the help.

Kim.

Depends on the crank condition. If it's scored or damaged your going to have to try and polish it in the motor if you don't want to pull the crank. There's lots of ways to do that like wrapping the journal with fine emery cloth and then a double wrap with a long strip of leather or rubber and use a see-saw motion to polish. Then bolt in a stock bearing and plastic gauge the clearance and then you'll know if you need .001 oversize bearing or what. But i've done this and seen it done several times for someone who only wanted to get a few more miles out of their engine and it seldom works long. Tough to get the crank journal polished round enough, likely the rod cap is out of round, likely something else caused this to happen in the first place. But it might be worth a try.

BTW I wouldn't do all the rod bearings if the others don't have a problem.

87xjco said:

Depends on the crank condition. If it's scored or damaged your going to have to try and polish it in the motor if you don't want to pull the crank. There's lots of ways to do that like wrapping the journal with fine emery cloth and then a double wrap with a long strip of leather or rubber and use a see-saw motion to polish. Then bolt in a stock bearing and plastic gauge the clearance and then you'll know if you need .001 oversize bearing or what. But i've done this and seen it done several times for someone who only wanted to get a few more miles out of their engine and it seldom works long. Tough to get the crank journal polished round enough, likely the rod cap is out of round, likely something else caused this to happen in the first place. But it might be worth a try.

BTW I wouldn't do all the rod bearings if the others don't have a problem.

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Thanks for the info 87xjco. Much appreciated.

As far as polishing everything I honestly don't trust myself with doing something like that. Not until I have an engine to try it on that is not going to need to be reliable on the trail. Which this engine will be my test engine to really get to know the inside of a 2.5. When it goes I will take it apart at home and slowly do a good rebuild, possibly a stroker if I can get that done.
I am just going to replace that one rod bearing and see what happens. If it goes it goes than. I have the original ready to put back in until the rebuit engine is done. Just need to get at least one weekend trail ride out of it so if I just replace the rear rod bearing hopefully it will last till the last day than it can blow up for all I care. Thank you everybody for all your help. Time to get everything put back together. I will let everyone know what happens. It will be a couple of days before it is running again. Need a new alternator.

Kim.

A scrachted bearing means either the engine turned without oil in it or the oil was not reaching the journal in pressure or quantity enough, in the first case you will have to keep an eye on oil level, in the second you have a problem that needs to be solved or you will ruin your new bearings in a short time.

I would go the full crankshaft regrind way to 0.010 and fitting a new set of main and rod bearings and in the way a new set of piston rings might be a new power lift for your engine bringing compression up to standard levels because by now it must be really low and thats why you are planning a stroker job.

By the way: Why stroke a 4 cil engine when you can get a 50% increase in engine size just by fitting the 4.0L 6L engine? I am sure it will be cheaper, more reliable and easier than the stroker way, but it's your call, just give it a thought before starting that project.

Good luck

SACEM

sacem said:

A scrachted bearing means either the engine turned without oil in it or the oil was not reaching the journal in pressure or quantity enough, in the first case you will have to keep an eye on oil level, in the second you have a problem that needs to be solved or you will ruin your new bearings in a short time.

I would go the full crankshaft regrind way to 0.010 and fitting a new set of main and rod bearings and in the way a new set of piston rings might be a new power lift for your engine bringing compression up to standard levels because by now it must be really low and thats why you are planning a stroker job.

By the way: Why stroke a 4 cil engine when you can get a 50% increase in engine size just by fitting the 4.0L 6L engine? I am sure it will be cheaper, more reliable and easier than the stroker way, but it's your call, just give it a thought before starting that project.

Good luck

SACEM

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Thanks for the help sacem. First off a 4.0 swap is way to difficult and not worth the time. I would need to modify my firewall alot to try that. I will stay with my 2.5 because I like that motor. It has potential and enough power for me and my wife. I will be building a 2.5 just to do it. I want to see what I can get out of it just because somebody hasn't done it to my knowledge. As far as having the crank done and all that other work I won't be doing that. This motor only has to last a weekend so I think with replacing that one bearing and running it only one weekend it should last. If not then I learn my lesson and I have info to put on this site for what not to do and what to do afterwards. Again thanks for the help.

Kim.

Is there a stroker crank availible for the 2.5? I know that to do a stroker 4.0 you need to use the 258 crank because it has a larger stroke than the 4.0 crank. It would be good to see a 2.5 done, its different and the 4.0 is based off the 2.5 so why not? Good luck with it

the_bandit87 said:

Is there a stroker crank availible for the 2.5? I know that to do a stroker 4.0 you need to use the 258 crank because it has a larger stroke than the 4.0 crank. It would be good to see a 2.5 done, its different and the 4.0 is based off the 2.5 so why not? Good luck with it

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There is no stroker crank available for the 2.5. Eagle just informed me of that. The wife gave me the go ahead to do whatever I want to do to the engine. Cost not over 2500. This will be fun!! Time to start searching the world wide web for info. If there are any ideas out there for the buildup let me know. It won't have to be done until late spring so I have awhile to research.

Kim.

Does it have a Orange Fram filter on it? If so, it's collapsed internally and caused this damage to your motor. I know of at least 20 others that have done this in the past few years. Fram's quality has tanked since foreign takeover.

For a motor replacement, how about a '95 YJ 2.5L with 5 speed and the EFI harness? Had about 70,000 miles when pulled (they put 36" tires on with 3.54 gears an "didn't have enough power" so they pulled it and are putting in a Chev V8) Oil pan has a dent (from being slid around the back of the truck while moving it)