05 STi engine (re)build..

[jakedoza]

Okay.. so here is some history on this. Summer of 2014 I lost a lower radiator hose and never knew it. The stock temp sensor never moved as water temp sensors do not measure air temperature.. Needless to say bad things happened. I pulled the engine and took it to a highly recommended machine shop and ordered goodies for it. JE .20 over pistons, Manley H beam rods with ARP studs and bolts, ARP Head studs, and new race bearings.

I had the heads rebuilt and a 3 angle valve job done on them and a new exedy stage 1 clutch. The machine shop built the short block and I put the rest together..

She ran great, but sucked the oil down 1 quart every 200 miles or so I did compression tests and leak-down tests and they confirmed that blow by was happening on cylinders 2 and 4. Compression was 120 on that side of the block and 155 on the other side. Something was going on.

Here are the photos of the pull a year and a half later (last weekend)

https://goo.gl/photos/V7JdHi4FLRTVYH6P7

The short block is now at the machine shop and I am awaiting the news..

 

[IGOTASTi]

That really sucks that happen.

 

[jakedoza]

The motor itself is fine.. it just used the heck out of oil.. so, there will be no spun bearings or anything like that.

 

[HolyCrapItsFast]

Take a look at the cylinder wall and the premature scuff marks. The photo of the cylinder showing a scuff mark at about the 2:00 location is the one that concerns me most. That is an odd place for there to be markings like that and it suggests faulty installation or a failed ring land. The motor was definitely not fine :tup:

On another note, if the oil consumption is due to a ring not seating properly then perhaps the machinist did not use a torque plate when boring or honing. This is a very important step because of how much the block halves flexes when the heads are torqued down. If you machine the block with a torque plate installed and then when the torque plate is removed after machining, the cylinders should actually be out of round at that point. Then when the heads are install the cylinder will go back to round by default. If a torque plate is not used during bore and hone, then it will show the cylinders to be round after the bore and hone but when you install the heads, they will deform and go out of round. A ring will not seat properly under this condition.

Please confirm that the machinist is using a torque plate

 

[jakedoza]

If you are speaking of this photo..



that is actually oil I did not wipe from the cylinder before I took the photo..

 

[HolyCrapItsFast]

Gotcha!

 

[jakedoza]

okay.. here is an update...

I spoke to the machine shop and they said that everything measured out okay. They said they could not find anything wrong other than the rings just were not seating due to slipperiness due to using a synthetic oil prematurely. They advise a conventional in all built engines. They said they were going to rehone and hot tank it and hope that the clearances are still good or I'll have to sleeve it or get new pistons.. argh.. I'm at a loss for words.

 

[HolyCrapItsFast]

So what oil did you use when you broke in the motor?

 

[jakedoza]

started with a conventional.. then switched to a synthetic.. (rotella t6) at I think about 500 miles..

This is how I have always been told to break in motors.. but does this pertain to boosted engines?

http://www.mototuneusa.com/break_in_secrets.htm