I have 1999 Subaru Forester with a SOHC/Ej25 that had an apparent engine knock. I replaced the block with a known good replacement, and experienced the same sound, so I replaced the block with another known good low mile block with the same results.

 

I have 2 blocks that are known to be in good condition and the original with an unknown history, all are making what sounds like a rod knock, but I find it hard to believe that it is. Every assembly was assembled using the original heads, new head gaskets, and new timing components. I have checked the vaulves, and they appear to be well within the specifications. So I strongly believe that they are not making the noise, and it does'nt sound like vaulve noise in the first place. Any ideas from the community would be appreciated.

Piston slap on #2#4 i remove the pistons and knurll them reinstall and noise will be gone i do this when i chage headgaskets come in knocking and leave dead silent. Piston slap gets quiter as it warms up rod gets louder as it warms up put the pistons to the top of bore and rock it top and bottom se how mutch rock it has

Any other rotating components swapped over during the engine changes?

What does "known to be in good condition" mean?

 

I have been irritated by the subaru "Piston slap/rod Knock" issue for a long time. FInally bought a complete rebuild and it is as good as my newer car.

 

I think these engine are easily abused by consumers. ID if there are other all aluminum engines out there, and I will bet there are none with split blocks. Except porsches maybe, and those get rebuilt every 50k miles it seems. So I wouldn't be surprised if you had 3 bad engines.

 

Ivans fix may work, but you need a knurler and a lathe to run it on. Seems like not an easy fix to me.

Does the car have an auto or manual transmission? Any chance the flex plate or flywheel is making contact with the bellhousing?

Have you used the same timing belt tensioner on all 3 of these blocks? Is it new or original? The tensioners used duering that time are known to flop around when they go bad and cause a knock that sounds very similar to rod knock.

thanks for the responses- ivan- good plan, i do not have the tools to do so un fortunately

 

known good means, they came out of parts cars that i drove- i knew it was quite

 

it has an auto trans, flexplate is possible i will look

 

new timing belt and tensioner was used, it is not flapping like some in the past have