MrPeepers

OK, I had an issue with what sounded like rod knock in my 95 4runner after running low on oil unknowingly. So I dropped the oil pan and oil pickup and cover, and cranked the motor with a ratchet to test the rod's play one by one. The #4 rod rattles like a kindergartener. I can wiggle it back and forth and hear it clank side to side. I pulled the cap off and the bearing doesn't look destroyed. What I am wondering is it possible for the bearings to wear out enough to allow the rod to wiggle side to side? Or is that more likely the wrist pin? I don't see anything that would keep it from wiggling side to side as the crankshaft is solid and there is a gap between the rod/cap and the sides of the crankshaft that keep the rod from sliding back and forth.

annoyingrob

If you can wiggle the rod back and forth on the crank, there's a problem. How hard was it to take the bearing cap off? If it didn't want to come off easily, it's very possible that the big-end is stretched, and it out of round.

MrPeepers

The cap came off pretty easily once I got the oil off. With all the oil on it was very slippery, but pulled it off with one of those blue shop rags. It doesn't seem out of round, it's more like it slides along the crank journal and hits the sides of the crank journal (not sure if I am using proper terminology). The cap doesn't look worn out on the sides, so I am wondering where it gets the play from as there aren't any shims or anything, and there is a gap between the sides of the rod/cap and the sides of the crank journal. Maybe I should take a pic when I get home to clear up what I mean.

Sportsmanphil

You can get a little play forward and back, but very little. My suggestion is to replace the con rod bearings with factory size bearings while you have it apart, as long as there is no damage to the crank.

If you catch rod knocks early enough you can get away with bearings. If a bearing spins or the crank is scratched, time for a rebuild.

MrPeepers

Yeah thats the plan. Got a set of standard size rod bearings on Rockauto.com for about $25, should be here tomorrow. The journals seem fine. I was just wondering what kept the rods from sliding on the journal front to back, or is it just the tightness of the bearings keeps it from wiggling much. Either way, keeping fingers crossed. Thanks.

Sportsmanphil

The rods will find their center.

Make sure to use some assembly lube.

annoyingrob

Standard size?

Correct me if I'm wrong, but aren't there like 4 "standard" sizes of bearings? The size of which you need is determined by the sizing mark on the crank, and on the rod? At least, that's how it is on the JZ motors, I assumed that it was consistent across all Toyota motors.

MrPeepers

Not sure about that. But every place I tried to order from had "Standard" size, and then a couple choices of undersize or oversize bearings. I was a little confused on why there would be undersize and oversize, unless it depends on if they mean the journal or the bearing? It was my understanding that you would just need oversize bearings if you got your crank journals ground undersize at a machine shop.

annoyingrob

I guess all I can say is try the "standard" size, then make sure you plastigauge the bearings to ensure they're correct. If they're out, re-order.

When I last did my bottom end, I took it apart, measured the crank and rod, found the difference, and calculated what size of bearing I needed. The sizes were surprisingly different across the different bearings.

MrPeepers

Yeah, that makes sense. I wish a local place carried them in stock. I actually considered buying all sizes since I could buy all 4 sets from Rock Auto for cheaper than a set at dealer. But Rock auto also sells them as single sets. I am going to plastigage the "standards" tonight and hope they all match. Wife is already complaining about this thing torn apart in the garage, so I may have to roll it out into the driveway while waiting for more bearings to come in the mail.

edit: What would you suspect causing htem to need different sizes? Think it came like that from factory, but the tightness of everything made it not as important? Or do you think the crank journals actually wear instead of bearings in some cases? Or perhaps heat causing the caps to expand? Just curious why that would be.

annoyingrob

They are slightly different from the factory, which is why Toyota usually stamps a sizing guide on the block, the crank, and on the rods, atleast on other motors they do. I can't confirm whether they do or not on the 22R motors. I never checked last time I was in one. The bearing surfaces are typically treated to be super-hard, and not wear down, but after several hundred thousand miles they've usually worn slightly, changing your tolerances. Rods will "oval" out over time, just due to age, and the movement they experience.

MrPeepers

Interesting. I've been working on it at night in the garage, the only markings that were really noticable on the cap was the cylinder number in dots stamped in (literally a . for each number). Although the cap did have a number on the side that looks like the rest of the number was on the rod itself. I'll have to look closer when I get home in some daylight. It's a 3VZE BTW.

b4wheeler

iTrader: (1)

I can check mine, but there are definitely different size "standard" bearings.

There should be a number marked on the rod cap and on the under side of the bearing...

Your best bet would be to get a copy of the FSM for your year engine and it will explain it very well.

MrPeepers

Ah ok. I also just found this thread, pretty good info. I guess first step is to plastigauge them all. Thanks all!

https://www.yotatech.com/forums/f116...g-math-181116/