Hi all, I recently purchased a 1987 Toyota Corolla FX-16 GT-S (Big Port) with 198k on the ODO, and paperwork for an engine rebuild 17k ago. It recently developed a knock, here are the details:
-It sounds more to me like a low end knock (rod, main, pin, etc) not a top end "tick".
-I can hear it most prominently under throttle (goes away if held at any rpm consistently, or rpm's idling down).
-It's most distinguishable between 2500-4000rpm (It may be there at higher rpm's but I can not hear it well enough to say for sure).
-I have great oil pressure.
-I have perfect uniform compression across all 4 cylinders.
-I did a spark plug pull test, and the noise seems to go away when I pull the #4 plug.

I am almost certain that it is a rod or main bearing, but if anyone has experience with another type of knock that fooled them, I would appreciate any info greatly. I don't mind tearing into an engine.. but unless they messed up the rebuild at the Hyundai dealership, or previous owner didn't break in properly (which I highly doubt) then I should -not- have a bearing going out at 20k on a rebuild.

You can check for worn rod bearings by removing a spark plug, turning the engine over by hand until the piston has gone just past TDC and on its way down the bore then carefully insert a long rod into the plug hole and push on the top of the piston. Any movement downward will be rod bearing clearance.

hmmmm..... broken ring land????

4AGE pistons have a "flaw" in their design... they use a slot, instead of holes, @ the oil ring. This slot doesn't support the ring lands under extreme issues, and it can cause a ring land to break

oldeskewltoy wrote:hmmmm..... broken ring land????

4AGE pistons have a "flaw" in their design... they use a slot, instead of holes, @ the oil ring. This slot doesn't support the ring lands under extreme issues, and it can cause a ring land to break

I have seen that happen on 2 engines but each engine showed a lower compression ( - 60psi approx) on the cylinder with the broken ring land.

You could try getting a stethascope from your local auto parts store and listening to the engine. Then you will know the general area where the knock is occurring (which will narrow your possibilities down).