Bearing tolerances ?

[xirdneh]

Ii have beenslowly disecting an engine that knocked. I never hear it knock but the guy I got it from told me it was a pretty good knock. I used plastigage on the crank mains and rods.
For the mains the FSM says maximum oil clearance is .0019 and Chiltons says .0026
I have three mains that are under .002 and two that are right at .002
the rod max per FSM and Chiltons is .002
all four measure at .002
I figure the bearings should be replaced but wonder about the bearing size designation stamped on the block
they can be numbered between 1 and 5
the mains are 22222 and the rods are 3222
i'm guessing the different numbers mean slightly differnt sized bearings
does any one know what the differnces are?
the guy had rebuilt the engine and drove it for a few years before the knock started
he replaced the bearings and pistons
i'm guessing he used std size bearings
if i buy standard bearings will the oil clearance drop enough?
so far i have not found anything that might have caused the knock

[Petros]

with oil clearances like that, the source of the knock was not the bearings. The engine should run just fine with oil clearances in that range. Presuming you have good oil pressure. are any of the bearings showing signs of hard contact or wear? lots of metal transfer, badly scored journals? Metal flakes in the oil pan? Likely not. If not I would reuse those bearings. The knocking is elsewhere.

When you have knock from the bearings you can see the damage in the bearings, no question about it. You might have a loose or damaged wrist pin, or you might have something loose inside the combustion chamber hitting the head every time in gets caught in the thin "squish" area of the combustion chamber (or already embedded into the piston top). Or it could be something in the valve train.

BTW, when I bought aftermarket Sealed Power pistons, they protruded above the block deck about .030", although the gasket is thicker, I was not comfortable with the pistons being higher than the block. I took it apart and had the machine shop mill .040" off the top of the pistons, and rebalanced them. Could be a similar problem? Even after market parts should meet factory specs, but not always. That could cause a big problem.

[xirdneh]

Petros
I took the piston/rod assys and the main bearing caps to a auto machine shop in Bremerton.
The main guy Marty has been good to me in the past so i asked him to look at them.
He said basically the same thing you did
He also put a Micrometer to the piston skirts and said they were good too
He thought maybe the starter fluid that the owner used may have dislodged carbon on top of piston
and also thought I should examine the head some more

The owner thought he had replaced the main bearings but they were marked on backside with a number "2" so I doubt he replaced them as he would have had to buy them from Toyota and he knows he did not do that.

[xirdneh]

oh yea
he said the bearings looked good
from what i could tell the journals looked real good too