I have a question for all of you that had rod knock in your evo 8/9 engine. I assume that rods and crank is damaged and needs to be replaced, but how often does it take the block with it?

Thanks!

 

It's doesn't unless the thrust bearing fell out.

 

I only changed the crank and rods when I had the knock along with the other parts.(oil pan, oil cooler, oil lines, oil pump, ect)

 

Thanks guys! Looks like I'll be starting another project!

 

On the original motor that came with my car which wasn’t maintained by previous owner. The crank went but the rods and pistons were still good and the bareblock was in great condition. But I didn’t throw a rod I spun a bearing.

 

Isn't rod knock usually a cracked crank and/or spun bearing?

 

my knock came from a spun bearing but the knock would be more pronounced as revs increased. So I shut my car down from the first time I heard the sound and never drove on it until I removed motor but damaged was already done to crank. Cause was contamination in oil.

 

So contaminated oil caused spun bearing that caused damage to crank? How did rod survive?

 

The term "spun bearing" is often misused. You can damage a bearing and have it result in rod knock. For it to be a spun bearing, the bearing halves (or one) have to actually rotate in the rod (or block if it's a main). Usually bearing damage starts and contact between the crank journal and the bearing. If the contact is severe enough or the engine is run for long enough after the knock is present then the bearing itself will spin.

In most cases, if the knock is caught fast enough, the crank can be machined back into usable condition (my crank has been ground twice now) and as long as the bearings aren't spun the rods and block will not need any machine work.

You have to run the engine for a pretty good amount of time for the bearing debris to make it into the head. The first time I wiped out a bearing in my evo there was a TON of trash in the oil pan, none of it made it up to the head at all. The only thing that absolutely should be replaced every time is the oil pump since it is the only part of the oiling system that's before the oil filter. The cooler should be heavily flushed and examined, replacement recommended.

 

The rods survived cause I shut it down quick. I still have rods and pistons I gave em to my friend I’ll have him take pics.

 

What you have stated is true no metal made it to head, but oil pan and strainer had a lot of trash.

 

That is very interesting. I bet you are one of the rare cases!

 

Yeah very rare because if I didn’t shut it down and get car towed and tried to limp it home it would have been a disaster.

 

Yeah, you always read, "I was only a few miles away when the [oil light came on] [temperature gauge when up] [engine started knocking] so I decided to limp it home.

 

I honestly don't get this mentality. If you're close to home, the tow is waaaaay cheaper than the cost of repairing severe engine damage. The only time I would limp the car is if it is super unsafe to pull over where I'm at, but the second you can pull over, shut it down.