dntsdad

Some of you may have seen my motor knocking thread located here:
https://www.yotatech.com/forums/f116...ooking-186183/

Was going to swap a 3.4 but that is going to have to wait as some unexpected things took all my stash money for that project and thus rebuilding this one is not going to happen also. Anyway, there is no way I am going to be able to rebuild the motor. Having the head "done", decking the block, and all the other little things that would be done "while I am there" puts that out of reach in time and on the wallet.

So options 2: Replace the main and rod bearings. I have to be able to go from the bottom to make this affordable and in my time constraints.
I have searched and read about guys doing this but I can usually not tell if they are working on a 3.0 or 22R. I have 3.0

My questions are:
1. I understand the theory of rod bearings be oversized but I dont want to have to maching anything. Just a quick plug in new ones along with the mains. I have read guys sticking slightly oversized bearing in to compenstae for wear without machining. This seems like catastrophe to me, if even physically possible. Anyone heard of this?

2. Tranny will have to come back to get to rear main bearing?

3. Assuming there is some scarring on the crank journal, what would be the worst case scenerio for adding new rod/main bearings? Would it simly make the same knocking noise from the get, or last a few thousand miles first?

thanks all

PlugItIn

i know you can do it on a 22re, on the 6 cylinder i'm not sure. I dont understand you first question though. Oversize bearings are used when the crank gets ground. As long as the crank journals look good you should use factory spec bearings not oversized. If the crank is scarred, you would have to pull the motor and take the crank out to get it machined, then you would need oversized bearings...

olharleyman

1. I understand the theory of rod bearings be oversized but I dont want to have to maching anything. Just a quick plug in new ones along with the mains.

Your going to have to drop the crank to get to the top bearings for both the crank and the rods so you might as well have the crank checked or you MAY end up in the same poistion your in now and all the work would have been for nothing. Even if you just replace with stock bearings your gonna have to PLASTI GAUGE to make sure they have enough or not to much opening for the oil to flow correctly.

2. Tranny will have to come back to get to rear main bearing?

Yes and no you will need to drop it ,the only other option you are going to have to get to it is to pull the motor so the easy way is going to be to pull the trans.

3. Assuming there is some scarring on the crank journal, what would be the worst case scenerio for adding new rod/main bearings? Would it simly make the same knocking noise from the get, or last a few thousand miles first?

It would be pointless at that point not to either have it turned or replaced because you may get 1 mile or 100 but you will end up replacing them one more time even worse is you do it and it all seems to be good to go then you hear it again , and worse case is that you eat the bearings and they go through the motor then you end up with a real problem.

Just do yourself a favor and do it correctly don't try to band aid it in the long run you will pay to much in time and money trying to band aid it to save a buck or two.

Cyberman

You can do the rod bearings from underneath, But I can't see you doing the mains properly without pulling the engine.

If you change just the rod bearings, you will need to use platigage to check the oil clearances. If they don't fall within tolerance for standard size bearings, you need to pull the engine, and get the crank machined for oversized bearings.

Plain and simple.

abecedarian

Plain and simple:
Rod bearings can be rather easily done. You pull the lower bearing cap, Plastigage it, divide the Plastigage reading by 2 (to compensate for the 0 clearance at the top), order bearings appropriately sized and install. Only thing not "simple" about it occurs when the Plastigauge reading varies significantly across the length of the strip / face of the journal, meaning the journal isn't wearing flat. At this point, the crank has to come out regardless of whether or not the main journals are in spec.

Crank bearings are a little more difficult to Plastigauge but not really. Keep in mind that the crankshaft isn't going to deflect or shift significantly (like the rods will) when the caps are torqued, so Plastigauge the bearing cap side and that's just about your exact clearance, not like the rods which can shift as you tighten them down. If the Plastigauge reading exceeds the max bearing clearance specified, you may be lucky enough to be able to order a bearing appropriately oversized to compensate without worrying about regrinding the main journals, but like the rod bearings, if the plastigauge reading varies significantly across the face of the bearing, the crank has to come out.

The above doesn't mean these are the best way to do it, but may get you a 100k or more if the crank isn't worn beyond spec and should be pulled.

yoterr

i vote 22R lol, sorry bout ur luck dude

dntsdad

Ok so i took all the caps off and replaced one by one. #3 cylinder (pass side middle) rod bearing was torn up. From what I can see the crank lloks good. No scoring, discolorization, and the rod appears as good as all the others as well.

I am going to try to replace the bearing without doing anything else. I figure the cost of rebuilding this motor I am already on the hook for, and probably wouldnt do that....just go to a 3.4, I'd just have to wait. SO all I have to lose is the cost of the bearing, oil and plasticgauge. and if it last me a few months then I will be happy with that.

Never used Plastigauge before so help me out here.

Ok so my question. I dont have a micrometer. So i am going to have to use plastigauges.
Would I:
a) take the trashed bearing out and insert the Plastigauge, torque the rod bolts(with no bearings in place), find the amount of clearance. Then take that number and subtract the bearing thickness and see if the difference falls in to clearance. If not, go to an oversized bearing to find the clearance needed.

FSM states (if i reading it right) that I have #2 stamped on all my caps so I use bearings with a thickness of .0586-.0587 and I should have a clearance of .0009-.0027

So Plastigauge measurement - .0587 should equal .0009-.0027

If so then just use a standard bearing and that should be ok.

Again, I know that this isnt the right way to do it. I am thinking like a slow leak on a tire. The right way is to fix/replace the tire but I am just "trying to keep adding air every so often"......just for a few months

dntsdad

Ok so i got a micrometer but I think that this motor has been bored out before. None of the specs come close to matching my book numbers.

I took out one of the good rod bearings to look for a number or something printed on it and I found a logo that looks like the picture. Looks like the logo is trying to represent a "C" and an "h". After the logo the number "1135L" is printed. One the other side of the bearing is a "large" 2.

Something like this for the logo. Pretend the circle was much rounder than my microsoft paint skills are able to draw:

Anyone have an idea of the brand/size that I may get from these?

dntsdad

Actually i think that the stuff is factory. I think i was measuring wrong. Found the logo. Its a company called Taiho. big japanese company that makes bearing and gaskets and stuff.

94runner4RJ

Keep us posted on how it works out. I would be intested to know how she runs after. Also, any photos of the torn up bearing? Thanks!

dntsdad

Any oil considerations that I should take after changing the bearings. Should I go with a thicker or thinner oil?

Any recommendations?

Thanks

dntsdad

Ok guys wanted to update this thread and ask a question.

I ended up changing the rod bearings from underneath. It really wasn't that hard and did NOT take out the differential. I did have to take the steering linkage apart and off to get the pan off, even with a 4" lift.

Anyway, decided to go with just a standard sized bearing. Cost me 33 plus oil to see if this can fix it for a while.

Started it up and it knocked for 3 seconds and then stopped. I let it get to normal temp and then wouldn it up to 3000 waiting for a rod to come out of the block. It hada slight knock but no rod out the side of the block.....so thats good.

Anyway, I'll see how long this lasts while I continue shopping for a used motor but at least I can drive it......slowly!!!

Ok for the question. I had a thought that it may be easier on the motor if I unplugged the #3 plug wire. My thinking was that this would cause less force back on the rod and thus the bearing. Obviously it lost TONS of power but runs decent without the plug wire on. My question.....finally.....

Am i helping the motor by running it without the plug firing or hurting it by causing it to unbalanced or whatever?

One more as well. My friend mentioned that higher octane gas may help me eeekk out a few more miles out of the bearing. This kind of makes sense but then again makes no sense. Opinions?? Guess it couldnt hurt.

dntsdad

nobody knows about running on 5 cyl??

PlugItIn

i don't think itd be bad for it...but your going to lose gas mileage and power (as you've noticed) You should use dino oil to break those bearings in...

Kiely

If you are in total "limp mode" and just wanting a couple more months life out of this engine, it can be done. You may want to disable the injector for that cylinder as well or you're going to be dumping unburned fuel into your exhaust and that's not good.

You can also slap a rare earth magnet (got an old computer hard drive laying around???) on the oil pan to help collect any ferrous debris being generated, preventing it from causing more damage to the engine.

Changing to a thicker oil can help if you are burning oil but if you're not I wouldn't worry too much about changing the grade of oil.

At the sametime you may be pleasantly surprised with how long an engine can run making that noise before it grenades.

Cross your fingers and drive her.

I provided a link to an auto wreckers search engine in your other thread to help you with that 3.4 search.

Here it is again:

http://car-part.com/